"'\

INTERPROFESSIONAL SEMINAR ON

DISEASES COMMON TOANIMALS AND MAN

SEPTEMBER 25 AND 26, 1958OMAHA. NEBRASKA

SPONSORED BYNEBRASKA STATE HEALTH DEPARTMENT

ANDDEFMTMENT OF MICROBIOLOGY

UNIVERSITY OF NEBRASKACOLLEGE OF MEDICINE

INTRODUCTION

Contained in this manuscript are the abstracts of paperspresented at the Interprofessional Seminar on Diseases Commonto Animals and Man which was held in Omaha, Nebraska on Sep­tember 25 and 26, 1958. This seminar was sponsored jointlyby the Nebraska State Department of Health and the Departmentof Microbiology, University of Nebraska, College of Medicine~

The sponsors of this program organized $nd conducted thisprogram in the hope that it would evolve into an annual regionalseminar or conference dealing with diseases common to animalsand man. Another desire of the organizing group was that theseminar be conducted on a professional level for scientistsworking or interested in these diseases rather than as a post­graduate teaching endeavor, although the latter might be anincidental, but important, by-product of the meeting.

The sponsors again wish to thank those who participatedin the planning of this meeting as well as those who presentedpapers or discussions during the seminar.

(No paper submitted)

~ABLE OF CONTENTSPage

Comparative Medical Research in Disease Control .t~o¢ •• ~~ •••••• o~.l

by J. H~ Steele

The Field Investigation of Zoonotic Diseases .~ •••••• ~ ••••• ~ ••••••7by J. L. Braun

Parasitic Forms Enzootic in the North Central states ~ ~;.. 'iW>"~· I, ~,,;, r"':::'l' II

Transmissible to Man ••• $ ••••••••••••••••••••••• I/l ~e.4< •• ~~.~·9

by H. J. Griffiths

Susceptibility of Various Species of Rodents Native to theNorthwest to Experimental Inoculation with the Plague Bacillus ••• ll

by M'!O Bacon ~

Inflammatory Ringworm in Manby G. E~ Radcliffe

t'Disease Freen Swine as Hosts for the Study of RespiratoryDisease ~ •••••••••• ~~ •••••••••••••••••••••••••••••••••••••••••••• 12

by G. A. Young J G·. W. KelleYJ N. R. Underdahl

Brucellosis in the United states, Iowa and Complications ••••••••• 13by I. H. Borts, S~ L. Hendricks

Vibrio fetus in Domestic Animals and Man•••••••••••••••••••• ~ •• ~.2lby s. M~ Morrison, V8 A. Miller

studies on Trichiniasis in Iowa ••••••••••••••••••••••••• ~ ••••••• 22W. J. Zimmermann, E. D. Hubbard, L. H. Schwarte

The Current status of Leptospirosis in the United States •••••••• 23by A. H. Quin

Antigenic Variability of Leptospiral Serotypes •••• ~ •• ~ •••••••••• ~24by Robert Pike

The HL Test and the Serodiagnosis of Leptospirosis •••••• ~ ••••• ~.~25

by C. E. Cox

A Serologieal Survey of Leptospirosis in a Nonselect Group ofHospital Patients and in Packing House Workers •••••••••••••••••• ~26

by N. G. M~ller, J. J. Bence

The Plate Agglutination Test for the Serodiagnosis ofLeptospirosis ••••••• ~ •••••••••••••••••••••••••••••••••••••••••••• 27

by A. H~ Killinger, M. B. Hays, M. F. Coria

Leptospirosis - Nature of the Infection in Animals •••••••••••••• 28by J. E. Mosier

The Control of Lep'bospirosis in Domestic Animals " e ••.~29by A., L¢ Brown

Diagnosis, Epidemiology and Treatment of Ruman StaphylococcalDisease with some Consideration ef th~ Disease in Animals •••••• ~31

••t·r,Ij{L.Smith, M. E. Godfrey, A. P. Wilson

Rabies - The Epidemiologic Pat.tern ,. 0 ft t •• " 32by I~ H. Borts, S. L. Hendricks

Studies on the Pathogenesis of Rabies in Insectivorous Bats •• o.~~33by S~ E~ Sulkin

Avian Tubercle Bacillus Infection in Man •••••• _•••••• f •• & ••• ~.~o34by A. G~ Karlson

Some Modifications of Virulent Mycobacteria Effected withEnzymeso. 0 • • • • ... • .. ~ •• 1'1 • • • • • • • • .. • .. • _ • • • • • ..... ~. ~ • • • • • • • • • 4t .. • • ~ • • .. t" .. 36

by W~ E. Engelhard

Recent Advances in Knowledge of western and st. Louis EquineEnc ttjt).J:la 1. i tis }•.••••• f ••••• II • , ~ ••• $ " • il .. ~ '"~ 37

Participants .~.~ ••••• ~ •••• e ••••••••••••••••••••••••••••••• ~.o~ •• 39

1

COMPARATIVE MEDICAL RESEARCH AND CHRONIC DISEASES OF ANDlALS

James H. Steele

The broad interest which has manifested itself in ohronicdiseases as pUblic health problems has raised questions in regardto the kind and incidence of these diseaaea in domestic animals.Veterinarians see many of 1;,h 1m tAeir clinics and.practices" in meat ins,eotiien and 'In'diagnostic laboratorieswlaara pathological examinations are made. Recently studies ilavebeen inaugurated in the comparative epidemiology of neoplastic"ileart, and degenerative diseases in domestic animals to determinetheir natural h1story* It is hoped that these investigationswill answer questions that will lead to the elucidatiQn of theirep1d.emiQlogy in animals and eventually man.

~eoplastic diseases

Veterinary medicine has a wealth of raw data whica eam beadapted by epidemiological methods to the servioe of mankind.The epidemiological approaek to the neoplastic diseases ofanimals oan prOVide data on the incidence, trends and distribu­tion; describe the natural history and may provide leads as tothe cause, and eventually the knowledge necessary to developla control program..

Little data on the inoidence of animal neoplasms has beencolleoted. Small studies in veterinary clinics, schools andabattoirs in Great Britain and USA reveal t1l.at tlie rate amonganimals varies from 50/1000 in dogs" 10/1000 1n horses andcattle, and considerably less in swine and-sheep. Colleotionof data of this type Should. be eo-ordimated. in regions and. com­pared with human data.

Veterinary medical investigators are in a fortunate positionto study the natural history of neoplastic diseases because oftheir opportunity to study these infections under experimentaleonditi0D.S. Natural oeeurring disease can be brought to clinicsfor f'urt:.- observation and attempts can be made to reproducethe disease. These conditions also lend themselves to therapeuticresearch programs,~which have Dean inaugurated in a number ofhospitals and universitl~~

The third aspect of the epidemiological approach is theque,stion as to cause and prevention. We have com.e to understandneoplasia as a particular host response to some inciting agent.The nost's response may be controlled by genetic factors or byan II immune response tt

• ne inciting agent may be physical, chemical,or infectious. The dog offers an excellent opportunity to testthese epidemiological methods in the elucidatiQn of the neoplasticdiseases. The dog more ~fian anyouher animal reflects the environ­ment and habits or man.

2

A study of canine lymphoma in New Jersey illustrates the pro-blems in setting up such a project. ~ese are:

1. The securing of base line data

2. The establishment of a reporting system

3. The availability of a diagnostic service

4. An evaluation of eases

5. The history of eaoh case and the tabulation of these data

The utilization or these data requires tnat medical epidemio­logists and statisticians participate in such studies so as todetermine what epidem101ogi~ clues may develop. Similar investiga­tiQns are being followed in regard to avian lymphomatosis to deter­mine what the effect of this disease may be as to man. Does expostreto animal lymphomatosis increase resistance or susceptibility? It1s diffioult to determine where these s~udies will lead to even­tually, but with the wealth of material available, the only limita­tion w111 be the imagination of the veterinary and medical epidemio­logist.

There are a number of other interesting investigations goingon in other parts of the USA and world. Bovine leukosis is Deingstudierd in Minnesota and surrounding midwestern states. Thisdisease has also been reported in southern Sweden and. more recentlyin Denmark and Germany. Some investigators state that it isoommunicable and have Been able to reproduce the disease. Aoond1t1en very similar ~o lung cancer, pulmonary adenomatosis hasbeen described in sheep in Ioeland and Peru. Researeh on this41seas8 leads one 10 believe that it may be transmissible, al~hough

'he incubat10n may be prolonged extending into years. This may Dea pattern of neoplasia in longer lived animals.

Heart disease(

During the past decade there has been a growing interest inlaeart disease of animals which reflects the increased investigationsbeing carried out on human keart disease. ~he interest of taeA.art disease speoialist in une comparative media~l aspects ofthis major problem has resulted in support that wa.s unknown a fewyears ago. A recent symposium on heart disease in dogs focusedtRe a.ttention of oardiologists and researchers to the possibilitiesQr investigation of natural occurring disease in a population thatcan be studied experimentally.

The material presented at the symposium had been collectedat.an animal hospital during tl1e past deca.de. nis study revealedta4t primary diseases of the heart are relatively uncommon, e.g.'iwnors and speoific infeetions, but that secondary lesions appearto De extremely frequent, a.g o inflammation sqDsequent to bacterial,

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viral and metabolic diseases. In a iotal of 3000 necropsies thefollowing types of heart disease were encountered in 619 caaes:

Lesions- Ine1dence

1.

7.

8.

Myo' (pan-) card.itis .. myocardial 8'dema, hemorrhage,necrosis, oalcification, 1nfarotion (Thrombosisand Bclerosis)

Vascular changes (inflammatory, degenerat1ve,metabolio), per1ar1ier1t16 nodosa" necrotizingarteritis, athero-and arteriosclerosis

Valvular d.1seases, valvulitis, edema, hemorrhageand fibrosis

Dilation, hypertrophy or atrophy

Endocarditis, subendocardial hemorrhage, edema,neorosis, calcification, and fibrosis

Primary- and seoondary neoplasms

Epi- and perioarditis

Congential cardiac anomalies

25~

15~

This tabulationd1saloses a striking frequenoy of inflammatorychanges as endb-, myo- and pancarditis which may occur either recal,disseminated, diffuse, 1nterstitial" anti acute,! sUbacute, chronio,granulomatous and/or sclerosing in type.

The opportunities tor various kinds of laboratory 1nvest1ga­viana are obvious.

Another study a. a sohool or veterinary medicine 1n the USAhas shown iba' the incidenoe of oard1ovasoular disease among dogs1s oons1derablyhigher 1ihan realized. Ine 01111 ot fifteen dogsexamined at this institution had some kind of aeart aBnormality.What the oaus~Qt these con.l~lons are 18 not known - nor whattheir relative inoidenoe may be in a given population 18 unknowneTo find further information about the disease in this populationan epidemiological suudy 1S Be1ng undel"iaken to try to asoertain.sa, the external or environment faotors may be .hat contributeto oan1ne heart d1sease. TRese studies are being taken- under the41reov1on ot the Nat1on~1 Heart Institute With veterinary epidemio­lQg1s~s. Naturally the data assembled will be studied closely todetermine wha~ its value may be in the epidemiology or heartdisease in man.

Studies like this should be encouraged in other 1nst1tu'1on8~

.ooun'ries and con'lnents so as to collect data on the prevalenceof oanine hear' disease and what may be tb, influences or 1nteol1ousd1s$as.~ ;11ma'.! nu'~111on ana anv1~anm.ni.

4

Another new development 'in the area of comparative heartQ:r..aeas9 research is to estab11stL a ~.A.iniG for the care of varioustypes of canine heart disease. This clinic will provide naturaloocurring cases of various types to the clinical investigators ofvarious therapeutic, surgical and radiological studies.

Arteriosolerosis sea~~ to turn up in animals Bomewha~ in pro­portion to the extent it is sought. Recently a report from Harvardpointed out that the disease was fairly oommon in South Americanmonkeys - ooourring spontaneously. The list of animals in whichspontaneous arteriosolerosis occurs is qUite extensive. The Philadel­phia zoo in a reoent report to the National Heart Institute statesthat 20 percent of the mammals currently being autopsied havearteriosclero,sis.

There ~re some indications that hypertension, the seoond rank­ing killer among the human oardiovascular d1seas~ may be a commonnatural disease in animal population. Studies in the USA revealthat there is ~ wide range of natural variation in blood pressurein dogs, Bome individuals being naturally hypertensive. Certaindogs are much more sUBceptible to experimental hypertension thano~hers. Other investigators have found that healthy dogs Bubjectedto ,severe dietary stresses and irregularities over a long period ottime 'will develop Bustained diastolic hypertension which may lasttar atter the experimental oonditions are terminated.

Aside from dogs it is known that hypertension oan be readilyproduoed in rats and rabbits. It is supposed that spontaneoushypertension can oocur in these and other wild animals, particularlywhen one considers the variable rigors of environment imposed bynature on wilGi animal population.

The inoidenoe of animal oongenital abnormalities is largelyunknown. One study recently published reported an incidenoe oflQ% among a large ,group of experimental dogs. Another veterinarianinvestigating the ino1dence ot congen1tal abnormalit1es in stillbornand newborn dead pigs reported 10 malformations of rive differenttypes in seven ot the 48 pigs examined - 14%. Five of the abnorma­l1ties were oardiovasoular. Thia investigator oomments that "con­genital abnormalities in swine have been so infrequently reportedin veter1na:l literature that it is impossible to estimate theirs1gnificanoe'.

All of this material is available to the diligent invest1gatorwho is willing to seek it out. The opportunities for laboratory,clinical, and epidemiological researoh are limitless. A oollectionor data from various geographioal areas should be undertaken as soonas possible to eluoidate the oomparative epidem1ology orthe variouscardiovasoular diseases among animals. These da'a may provide in­formation or great value 1;0 'bhe elucida'b1on or the epidemiology otcardiovasoular diseases in humans.

5

Degenerative diseases

Few domestio animals live out their no~nal life span exceptanimal pets, viz. dogs, cats and birds. But even with these limita­tions the field of comparative medical studies among domestic andpet animals offers unusual opportunities. Many of the degenerativediseases that are important to human health occur spontaneously inanimals that live close to man and are exposed to the same environ­mental influences. Probably one of the most important from a publichealth aspect is arthritis. Millions of persons as well as manyanimals, especially swine, are affected by this malady. Comparativemedtal studies on this disease are now being carried out in someveterinary and medical research centers. An aspect that needsfurther exploration is the epidemiology of the di\sease in bothman and animals. It would be very desirable if comparative medicalinvestigations could be established in otbe~r parts of the world soas to shed light on the geographical distributions of this univer­sal affliction of man and supposedly animals.

Blindness in some cases is a degenerative disease that affectsmany humans and a surprising number of certain animal species, ·viz.horse and dog. Most of these conditions occur in the ageing animalbut frequently it is noted in animals that are relatively young.In the horse a recurrent iridocyclitis is not uncommon which leadsto permanent loss of vision as the lens becomes opaque. The primarycause of this disease is still to be determined. !n the past, thecause has been thought to be genetic transmission, nutritionaldeficiency (riboflavin) and more recently leptospire infection.Conservative opinion is that it is a degenerative disease of un­known etiology.

Dogs frequently have opacities of the lens that are non-spec1£1cas to origin. Some respond to medication, but even in these theoondition is re-oceurring and eventually causes blindness. vlhenthat oocurs, only removal of the lens will provide any relief. Thenatural history of this entity needs investigation as well as theepidemiological pattern. It again is an ideal sUbject for compara­tive medical and epidemiological study.

Liver diseases including cirrhosis is found in many speciesof animals. Many of these have been studied as pathological diseasesbut again little has been done as to the distribution or incidence,.

Metabolic disorders of many types are seen in different animals.One of the more interesting is gout in ohiokens. Fowls have theability to excrete large amounts of uric acid which are convertedto urates. What occurs to change this and allow the accumulationof these substances in the fowls' tissues is a ohallenging compara­tive medioal disease problem.

Allergies of all types are seen in some animals. Some aresensitized to therapeutio agents, feeds, and others by endogenosesor autoallergena. The most serious are those due to infective ag'entsresulting in an infectious allergy. The resultant hypersensitivityhas primarily vascular localization.

6

Anemias of many kinds are also frequently encountered. Com­parative hematology is an area which is just beginning and shoulddevelop rapidly with the extensive interest in blood research.

Diseases of the skin are numerous among domestic animals andpets. Some are metabolic, others are reactions to economic poisonsor insecticides, while others are infections. All of these areareas that have received little attention until recent years.

Many animal pets lend themselves to gerontological research ­the dog, cat and some birds are being used already. The dog is pro­bably the ideal animal because so much is already known about hisphysiology, nutritional requirements, and susceptibility to disease.Also large colonies can be readily managed because of the experiencethat has been accumulated in recent years. Some of these groupsthat are being used for genetic studies would lend themselvesadmirably to ageing studies. The dog also has the longest naturallife of the smaller animals in clme contact with man.

Animal psychoses

It has been long known that animals are susceptible to inducedpsychotic ills. All degrees of derangement can be created in animalswhich are susceptible. The circumstances that permit this are notwell defined except to say that certain breeds which are highly in­bred seem to have the lowest threshold for artifically created mentalillness. Animal psychology has advanced rapidly in the laboratorybut there is need to carry out field studies to determine if thereare epidemiological patterns that may reflect their breeding, environ­ment or human relationship. A world wide survey may provide cluesof inestimable epidemiologic value. It is important that this areaof comparative medicine receive the recognition and support needed.Scholarships for veterinarians who wish to study animal psychologyshould be established.

7

THE FIELD INVESTIGATION OF ZOONOTIC DISEASES

J. L. Braun

Many diseases, once of particular public health importance,are now well contro~led and oonsequently are no longer of paramountpublic health significance. As a result, other diseases, such asthe zoonoses, have assumed positions of relatively greater signifi­cance to the public welfare. Necessarily, medical research interestshave undergone a similaIl change. Field investigation is an integralpart of the science of epidemiology and, as such, has always conati­tu ,ed an important aspect of medical research. The gI'*eater emphasison diseases such as the zoonoses has resulted in an increased demandfor field investigation.

Zoonoses resear-ch, by its very nature, necessitates that humanmedical and veterinary medical talents be coordinated. One of thespecific areas demanding such professional cooperation is that offield investigation. tIuman epidemic diseases are subject to investi­gation by classical analytical epidemiological met ods. Conversely,zoonotic d1seas~ by their very nature, are not subject to analyti­cal epidemiolog:t.cal methodology 0 Zoonotic diseases seldom, if ever,occur in epidemic form among human populations; more often, suchdisea as occur in endemic or sporadic form. Thus, it is necessarythat Such diseases be investigated utilizing comparative and des­criptive epidemiological methods; each case must be investigated~

evaluated and compared with other similar episodes. Consequently,the adequate field investigation of zoonotic diseases necessitateson-the-soene investigation. A well trained field investigator canfunction most praoduct1vely in this area of professional overlap byinsuring rapport between professional disciplines and by collectingnecessary epidemiological and epizootiological information. Improvedlaboratory diagnost'1c aids r·equire many human and animal blood andtissue specimens; ~uch can be collected by a well trained fieldinvestigator.

The infectious disease research program at the Institute ofAgricultural Medicine is primarily a field investigation program.This approach may be exemplified by a brief review of the humanleptospirosis program now' under way. All human blood specimensBubmitted to the Iowa state Hygienic Laboratories for febrile agglu­tination studies (predorn1.natly brucella serologies) are screen testedfor leptoBpiro~is. To date, a total of 12,250 specimens have beentested. and 1.4.% found to be positiva l» All specimens found to bepositive at a titer of 1:40 or greater are investigated in thefield.. The submitting phy'sician is contacted and the case reviewed.On the basis of the positive screen test serology and preliminaryinformation secured from the at·tending physician, the case is evalu­ated as to its possible leptospira etiology. If indicated, thepatient is interviewed~ a complete occupational and environmentalhistory obtained, clinical and hospital records abstracted and a_

8

repeat blood specimen Becured~ In addition, whenev~r possible, aneffort is made to substantiate the suspect exposur·e source by obtain­ing blood specimens from SUSpefJt infected contact animals n If suchcases qualify on the basis of a 4-fold 'titer rise, compati·bl~ clinicalsymptomatology and documented exposure source, they are accepted asconfirmed episodes of human leptospiroslsi To dat.e a total of 13such cases have been documented. Our experience indicates a neces­sity for personal field investigation of such cases~ Only by thismethod can the necessary information be seoured.

(

Similar field investigation efforts have been successfullyapplied to Q fever in both man and animals in Iowa~ Likewise,psittacosis, ringworm and enteric infections are most successfullyinvestigated by these methods.

A field investigation program of this nature requ1I'es adequateand specialized equipment. W'eatrer conditions necessitate use of adependable field vehicle; commercial station wagons have proven mostpractical~ In addition, equipment must be available for both humanand animal investigations. The collection of human blood samplesis facilitated by use of the commercial Shepherd blood collectingtubes; experience proves these tubes to be more efficient, dependableand inexpensive than regular syringes ll Minimal uanimal equipment,nconsistBof rubber boots, coveralls, gloves, boot brushes, buckets,halters, nose tongs, lariats, and suitable blood collecting parapher­nalia.

Recent developments in many local, state and federal healthorganizations serve to point out the feasibility of utilizing laypersonnel in the role of medical field investigators. Training 1nbasic epidemiology, the principle of infectious disease, and themechanics of blood sample collection are prerequisite to the effic1sIltperformance of lay individuals in this capacityc Properly oriented,such individuals have proved capable of conducting thorough investiga­tions while dealing with patients, veterinarians, physicians andhealth officers .•

9

PARASI~rjI(G FCHMS ENZOOTIC IN 'I1HE NOR'rHCENTRAL STA~En TRANSMISSIBLE TO MAN

HQ tT. Griffi ths

Parasites infecting man are usually olosely related to thoseof domestic an:l.mals. The problem of paI1l8sites in man and 'animalsdiffers greatly because of the types of sanitation practided"by thesetwo host groups.' Human preventative parasitology has been acceptedby those in North America through the adoption of such conveniencesand practices as sanitary plumbing, personal hygiene and meat inspec­tion.

Parasites of animals infecting man in the north central statesare:

(1) Ascaris lumbr1i{;o1des (man) and Ascaris suum (pig) - Thesetwo helminths are mor~holog1cally similar bu~ are 01oIogically differ­ent species. Pig ascaris will hatch in man and migrate to the lungswhere it is ultimately destroyed. Although it is estimated thatabout three million human ascaris infections occur in the ,Unitedstates, ascaris in pigs plays no known role in the epidemiology ofhuman ascariasis.

(2) Toxocara canis (dog) and Toxooara cati (cat) - The disease,visceral larval m!grans, oaused by the migrating larvae of T. canisand T. cati has been recognized and substantiated during tlie pastfive-years. The clinical syndrome associated with the migration ofthe larvae to the extra intestinal viscera of the unnatural host,is oharacterized by hepatomegaly, intermittent fever, nausea, vomit­ing, cough, weight loss, anorexia and marked abdominal pain. Thisinfection is usually seen 1n young children of the ttdirt eating age"or under 3 years. The incidenoe of visceral larva migrans is greaterin the southeastern part of the continent although it has been re­ported in children from the north central states. Keeping pets,dogs and cats, free of this parasite is to be recommended as a pre-.ventat1ve measure against human infection.

(3) Trichinella spiralis - This helminth shows p~aotioally nohost speCificity. The Un1~ed states has the doubtful distinotionof having the highest incidence of triohinosis (about 16%) in theworld. Current outbreaks are deteoted mostly among racial groupswho enjoy uncooked sausage made by some looal butcher who has aspecial recipe handed down from generation to generation. In 1952,laws were enacted to cook all oommeroial garbage fed to swine. Atthe present time, 46 states cook oommercial garbage. In years tocome, this should have a oonsiderable effeot on lowering the incid­ence of trichinosis in man and animals.

(4) Trichobilharz1a~. - Man is aocidently attacked by theschiatosomecercarlae trom l"'Iukes of the genus Trichobilharzia causing ceroarial dermatitis (swimmer's itoh). These flukes live inthe blood vessels of aquatio birds suoh as duoks" loons, etc., Cercariai

10

infection gives rise to in'tense itc.hing v:rh1ch may last 1-4 days.Swimmer's itch is quite common in many fresh water lake in thenorth central states. Control 1s achieved by the application ofoopper sulfate to the habitat of the intermediate host, the snail.Human infections are minimized by rubbing dry with a rough towelimmediately after coming out or infected water.

(5) Diphyllobothrium,latum - The broad fiah tapeworm, Do latum,oocurs in" certain lakes areas of Minnesota, Michigan and Florida.Infections are invariably traced to eating raw or insuffioientlyoooked fish, a custom among various groups of people such as theSoandinavians, Russians~ Jews, etc. Human infections may oftenproduoe a condition similar to pernicious anemi&o

Other parasitic diseae~s oommon to animals and man of a greatergeographical distribution are discussed. It is emphasized thatglobal travel, concentration of people and animals and indiscrimi­nate shipping and movements of man and animals ofters great oppor­tunity for the introduction of new parasites to new geographicalregions 0

11

SUSCEPTIBILITY OF VARIOUS SPECIES OF RODENTS NATIVE TO THEN'ORTHWEST TO EXPERIMENTAL INOCULATION WITH THE PLAGUE BACILLUS

Marion Bacon

At the State College of Washington, wild rodents including62 meadow mice, Microtus, 72 deermice, Peromyscus maniculatus,14 pocket mice, Perognafhus E..arvus, and I sagebrusnvo"Ie, L~g~,were inoculated wi iih gl?aduatea dosages of virulent s trains o~Pasteurella pestis originally isolated fromferal sources~ These"roaents WEi"reJ'Udged to be the species of mammals most common ineastern and central Washington and among those most apt to comeinto contact with other species. The Peromyscus, Microtus andParognathus have closely related species or subspecies residentin 'the-PMIQWest"

Animals surviving inoculation were sacrificed and tested forthe presence of bacteria in their tissues and for aggultinatingantibodies in their serums.

Both Microtus and Peromyscus included some plague-resistantand some plague-susceptiDIe IndivIduals. Some of these micesuccumbed to dosages of about 10 bacilli each; others surviveddosages of over 100,000 bacilli. Perognathus seemed entirely sus­ceptible to fatal infection with virulent ~. pestis.

Of the animals surviving the inoculations, two out of 23Microtus and 2 out of 23 Peromyscus showed positive agglutinationn-ters ~ P~. pestis occurred in the tissues of one survivor amongthe Microtus and 2 of the surviving Peromyscus~ Of the animalsdead of plague infection intense bacteremias were found in nearlyall of the Microtus and all of the Perognathus; in Peromyscusbacteremias-were less intense as a rUle, but usually detectable.

The four strains of P. pestis used as inoculums showeddifferences in their virulences to white mice. All seemed lesspathogenic to Microtus and Peromyscus than to white mice~

Of the ten additional Peromyscus fed with plague-infectedcarcasses, nine developed fatal plague infections.

The one Lagurus was susceptible to plague-infection, butshowed a longer survival time than the other species tested and asomewhat different pathology.

It was suggested that Peromyscus and Microtus may play animportant role in maintaining plague in an enzootic condition.Perognathus probably cannot maintain intraspecific enzootic plague,but may have enzootic importance where other mammalian speciesare present. Carnivorous and cannibalistic habits may be importantmeans of transfer of plague infection among some kinds of rod6nts.

12

"DISEASE-FREE" SWINE AS HOSTS FOR THE STUDY OF RESPIRATORY DISEASE

G. AQ Young, G. Wo Kelley, and N. R. Underdahl

study of chronic respiratory infections of viral origin inexperimental animals has as a limitation, the natural oocurrenceof similar diseases in most species. Experimental respiratorydisease imposed upon naturally occurring respiratory infection issimply not interpretable~

One other limitation to experimental animals handled byattendants is possible exposure to human diseases and formationof antibody in inapparent infections o The immunity of such ahost may block experimental transmission of 'the disease with animmunologically related disease agent~

Both of the above problems are eliminated in the use of"disease-free" baby pigs as the experimental hosto Pigs areobtained t1 surgically" before expected birth and delivered in asterile environment. They are kept under cover and housed inisolation units (modified Hosfall-Bauer). Sterilized and repas­teurized cows' milk is fed to these pigs. They do not come incontact with attendants or other animals so are free of pathogens.Since antibody does not pass the swine placenta, immunity in swineis derived entirely from the mother's colostral milk. These pigsreceive no colostrum so are immunologically naked.

Use of the above type pig in experimental respiratory infec­tions was discussed. Emphasis was placed on an atypical pneumoniacommon to swine and possibly related to some of the atypicalpneumonias in man.

13

BRUCELLOSIS IN THE UNITED STATES AND IOWA AND COMPLICATIONS

I. H. Barts and S. L. Hendricks

In spite of the marked reduction in b~ucellosis in theUnited states through the controlling of the disease in thebovine and through the pasteurization of milk little attentionhas been paid to swine brucellosis which is and has been themajor source of human brucellosis in Iowa, and other hograising states. Had some effort been devoted to the controlof the disease in swine, human bruoellosis today would be ata relatively irreduceable level.

Figure 1 shows the reported incidence of human bruoellosisin the United states and Iowa for 5 year periods save for theperiod of 1905-24 and the singular years 1955, 56 and 57.

Figuce 1

CASES28.000

24.000

20.000

12,000

8,000

BRUCELLOSISUNITED STATES AND IOWA

25,7!59

o U.. S. CASES

_ IOWA CASES

17,934

14,618

8,227

4,000

128

1905-24

14

Figure 2 shows that as brucellosis in the United statesas a whole has declined and that the percentage of Iowa caseshas increased in proportionto other states. The reason forthis percentage increase is that little or nothing has beendone to control swine brucellosis. Although bovine brucellosishas been a reportable animal> disease in Iowa for years it isinde.ed surprising that with all the past and present knowledgeaccumulated in Iowa that swine brucellosis has not been areportable disease.

In the year 1955, Iowa reported 405 or 28% of those re­ported for the entire United states while 3 states Iowa,Illinois, and Minnesota reported 661 cases or 46% of thosefor the United states. Similar findings are recorded for1956 and 1957·.

Figure 2

CASES28,000

BRUCELLOSIS

1930-34 1935-39 1940-44 1945-49 1950-54 1955 1957

-- UNITED STATES CASES--- IOWA CASES, PERCENT

OF UNITED STATES2aO% 28.0%,--,

/ ,/ ,

/ ,,'22.6% '~I1'%

I16.6% I

," II \ I

I \ /

/ \ ~~-r{5%I {4% //I ',,,I .........,

I 4.6%I

4,000

8,000

16,000

24,000

12,000

20,000

15

Table 1 shows that Iowa for years has been among the10 leading states in the reporting of human brucellosls.

That we are dealing with swine brucellosis is well docu­mented from epidemiologio data, tissue and blood culture studiesand the typing of the species of brucella isolated from human,animal and milk sources.

Table 1

R~~PORTED HtJ1A~ BIWc.:ElJ,OSIS IN UNITED STATilS* • INCIDl!:NCE IN 10 WDIIiG ~ fATFS194, • 19$1

1945 ls'46 1941 1948 1949 19$0 19S1 1952 19$3 19S4 19$$ 19$6 1~$1

1 Texas Texas Iowa Texas Ill. Iowa iova Iowa Iowa Iowa Iowa Iova Iowa616 750 902 561 501 ,49 761 124 5St> )51 40S )60 2!h

2 Iowa Iowa Ill. Ill. Iowa Ill. IU. Ill. IU. nl. nl. n1. nl.482 638 555 515 371 447 445 294 24) 20) !ho 133 120

3 Ill. Ill. Texas Iova Texas Texaa l~lnn. Ninn. MiM. Minn. Minn. 1-:inn. Neb.325 480 4r,() 412 341 288 189 139 13) 151 116 63 6)

4 ~iM. 'hisc. Wise. Colo. I'.inn. l:1rm. ~iac. ~'Iisc. Te.<aa Wise. Wise. Hich. Kan.312 3L6 430 249 211 228 140 138 laL 116 68 52 57

5 'tlise. :-:1nn. EilUl. 1_.Y. ,vise. ''':18c. T. ru Texas iliac. ::ich. Mich. l.b. KiDn.283 331 331 246 221 181 123 118 91 III 60 52 51

6 N.Y. r:.y. I-ach. tUM. }:ich. NoY. Calif. Calif. CaUf. TeJC&8 Calif. Kan. Mo.279 300 304 229 196 14~ 100 115 68 8!1 56 48 41

7 CaUf 0 CaUf. Calif 0 Eich. Okla. Kan. Nof. H.H. lti.ch. Mo. Texu Calit. Callt.27~ 293 2136 221 ~6 143 89 77 68 54 51 40 37

8 IUeh. Kan. i~oY 0 Ohio HoY. Calit. Ga. Kan. Ga. La. S.D. lfo. Wise.250 211 262 191 149 121 '34 75 6) 49 49 39 )1

9 Kan. Oa. Colo. CaUt. Ind. Okla. Va. Okla. Kan. CaUf. l-lo. Oa. TenD.209 169 183 157 137 102 81 68 S9 L8 39 39 29

10 ONcon Ind. Conn. Ga. Ga. Ga. Pa. Oa. Va. Va. Ga. s.n. S.D.153 161 1'31 146 130 99 78 64 $8 46 35 33 2L

17. S.1,4h4Total 5,049 5,887 6,321 4,991 4,235 ),510 3,139 2,5.3'( 2,032 1,623 1,300 98)

*So~1 lEPUS Morbid! ty and l'iortal1ty Report••

STATE HrGIENIC L'I R<mA'l'ORY ieptember 1, 1958

Table 2 shows the number and speoies of brucella isolatedand/or typed from individual human oases in Iowa.

16

Of 533 strains of brucella isolated from individualhuman cases, Brucella Buis was isolated from 335 (60.8%)cases; Brucella abortus from 142 (25.6%) while 76 or 13.6%were Brucella melitensIs. Had we not typed all strains ofBruceIla isolated from human, animal and milk sources, wewould not have been aware of the problems in Iowa. Epidemio­logic and laboratory studies reveal that all of the melitensisinfections had their origin in swine; hence, in the overall,74.4% of the human infections originated in swine.

The great majority of human cases in Iowa are amongmale farmers, packing house workers, veterinarians, stockhan'dlers etc. and are traced to direct contact wi th infectedanimals, tissues or aborted products. The organism will passthrough the unbroken skin but infection is enhanced throughthe broken skin.

Table 2

BRUCELLA ISOLATED FROM INDIVIDUAL CASESIN IOWA.

Brucella Brucella Brucella.abortus melitensisSUIS

Blood 306 135 75

Compl icati"9 Lesions 29 7 1

Total 335 142 76

17

Figure 3 shows that brucellosis in Iowa is greatestin areas where packing plants processing hogs are located.

Figure 3

Packing PlAnts. Employees, Human Brucellosis Cases in Iowa

= 1956 Cases1957 Cases

NumeratorDENOMINATOR =

1I1rcllCLL

u- 50-100 EmployeesE- 20-50 "F- Under 20 (Not shown)

'''ANKLIN .vn£"1 1

T ,...

UMO ntWO

A s 2IT

HANCOCK

J....

AIJAMI /INION CLA"KC LUCA4

1 1 ..L )

T "2 IM« TAnOtt "INOHLD DICATUlt ",,,,,,,, A_IIt1OK DAtil.

)E J- 2,... T

OIC'ID&.A DICI~NSON DIller 1f0Stl",."3 -!..I T T

NIIN cUN10 L\ALrO

.L ..!.. 0'" ,...

L~Qe.ndA- over 500 EmployeesB- 250-500 "C- 100-250 "

Table 3 shows brucella species isolated frommLlk ofindividual dairy herds and from swine tissues.

Of 75 strains of brucella isolated from milk of individualdairy herds, 70 were Br. abortus while 5 were Er. Buis. Of the5 Br. suis strains, 3 were associated with epiQemics of humanbrucellosis, traced to the ingestion ct: U1pasteurized milk from

18

herds allowed to mingle with infected hogs. In one epidemic,77 cases occurred with multiple cases in several familteswithin three weeks' time. The outbreak promptly ceased follow­ing pasteurization of the milk supply. Br. suis was isolatedfrom the milk of 2 of 4 veacting cows in~e herd and from 13blood cultures from the ill patients.

The virulence of Br. suis strains isolated from cows asjudged by pathogenioity-rn guinea pigs and clinical illnessin the patients was considerably less than in oases of Br. suisinfections in humans secured by direct contaot with infectedhogs. From our experienoe in 3 epidemics of swine brucellosistraced to milk the presumptive evidence is that the strains arereduced in virulenoe by residence in oattle.

Table 3

BRUCELLA ISOLATED FROM INDIVIDUAL IOWA

DAIRY HERDS OR ANIMALS.

MILK

ANIMALS

* 1 from hog tissue** All from hog tissue.

Brucellasuis

5

1

6

Brucellaabortus

70

2*

72

Brucellamelitensis

o

14 **

14

19

Table 4 shows the complicating lesions of brucellosisin Iowa and the species of brucella isolated from the lesions.

Complications in the course of brucellosis are notunusual particularily in Br. suis infections. Of 37 bacterio­logically proven cases, 2~were Br. aUis, 7 Br. abortuB and1 Br. melitensis. --

Brucella suis infections in man and guinea pigs simulatetuberCUlosIs In many respects.

Brucella may lie latent in the recticu10 endothelialcells following apparent clinical recovery. Brucella havebeen isolated during the primary attack and the same speciesfrom lesions following injury two years or more later withapparent well being in the interval. Within 24 hours followinginjury the patient becomes febrile, complaining as in the pri­mary attack and the aame speoies isolated from the site ofinjury.

Table 4

COMPLICATING LESIONS IN HUMANS VERIFIED BY THE

ISOLATION OF BRUCELLA FROM THE LESION

Brucella Bruoella Brucellasuis abortus melitensis

Subacute Bacterial Endocarditis 7 1 1

Pyelonephritis 4 1 0

Meningo-encephalitis 3 1 0

Osteomylitis 3 0 0

Cold Abcess 3 0 0

Spondylitis 2 1 0

Pleurisy with Effusion 2 0 0

Cervical Adenitis 2 0 0

Cholecystitis 0 1 0

Hydro-arthritis 0 1 0

Ovarian Cyst 1 0 0

20

Table 4 Cont1d

Peritonitis

Liver Abcess

Thyroid Abscess

Total

Treatment

o

1

1

29

1

o

o

7

o

o

o

1

In our experienoe with bacteriologically proven Br. auisinfeotions a single antibiotic is insufficient to control theinfection. Similar situations are recorded by Herrell and hisassociates at the Mayo Foundation and by Castaneda in Mexico.Conoomitant therapy recommended by Herrell, Castaneda and othersconsisting of dihydrostreptomycin 1.0 gms. intramuscularilyevery 12 hours for 12 - 14 days together with simultaneousadministration of an oxytetracycline 3 gms. by the oral routeevery 24 hours in divided doses every six hours is the treat­ment of choiae.

In the presence of complicating lesions, therapy shouldbe continued for 28 days as noted except that dihydrostreptomycinis reduced to 0.5 gms. twioe daily.

Summary

1. Brucella infections of swine origin predominate in Iowa andother areas of the midwest, thus infection in the human willnot be eliminated until the disease is also controlled inswine.

2. From animal inooulation studies of cultures and clinicalevaluation of patients in rowa, Brucella suis infectionsare far more serious and more complioations are encounteredthan from infections due to Brucella melitensis or Bruce]aabortus. '

3. There is evidenoe that Brucella suis isolated from infectedcattle is of lower virulence than strains isolated fromhumans infected by directoontact with swine.

4. Concomitant therapy with dihydrostreptomycin~anda broadspectrum antibiotic is essential to adequately therminateinfections in the human due to Brucella suis.

5. Recurrent brucellosis is usually the result of inadequatetherapy or failure of the drug to penetrate reciticulo­endothelial cells containing viable, !tent brucella.

21

VIBRIO FETUS IN DOMESTIC ANIMALS AND MAN

So Mo Morrison and Vo Ao Miller

Vibrio fetus is the causative agent of a very widespreadconta~ious abortion, usually called vibriosis, of sheep ( andgoats) and of cattle (and buffalo) 0 Eighteen documented casesof human infection with this organisms have been reported f:romFrance ,and the Uo So The organisms from each of these speciesare homogeneous morphologically and biochemically but hetero­geneous immunologically 0 Similar organisms, some non-pathogenicand Bome causing other disease conditions are knowno

In cattle the disease is transmitted by the bull whichharbors the organism in the genital organs o The cow abortsbefore the sixth month of pregnancy, experiences difficulty inreconceiving and, it is believed.? transmits the disease to itsfemale offspringo Outbreaks involving 20 per cent of the herdare known. In sheep the outbreaks of vibrionic abortion aremore explosive, involving as high as 60 per cent of a flock,with abortions late in pregnancyo The disease is transmittedby the oral route probably by contact with expelled fetal mater­ial in feeding o The ram seems unimportant o After abortion theewe has a normal breeding year.

The pathology in both sheep and cattle is similar, themost striking lesions being in the cotyledons of the placenta.Uterine damage is characterized by edema and hemorrhage in ,the 'caruncles and the intercaruncular areaso In the fetus, edemaof the umbilical region with sanguinous fluid in the bodycavities is presento

In the human, no definite conclus:tons can be drawn fromthe few studied cases o Three cases were in ~regnant women,two ending in abortiono The other cases (13) were in adultmales, five of whom worked with animalso The disease was oftendiagnosed as brucellosis and even malariao The moot consistentsympton was undulating fever and nmny patients showed chills,headache, respiratory difficulty, weakness and anorexiao Thebacteremia was followed by paralysis and heart damage in somecases, butthe true relationship is not ¥nown o

Improved isolation and diagnostic procedures are necessaryto determine the extent of this disease in humans.

22

STUDIES ON TRICHINIASIS IN IOWA*'

w. J. Zirrunerman, E. D. Hubbard, and L. H. Schwax'te

studies during 1944-46 showed the presenoe of Triohinellasplra11s in about 12 percent of 904 Ba~les of oommeroial porksausage. Similar studies during 1953-58 revealed only 1.4 percentof 6,115 samples of non-prooessed pork sausage to be positive.During the past year the ino1denoe of T. ~1ralis has been about0.3 per oent. This deorease may reflect ··e ef'I'eot of garbageoooking regulations as wall as better swine management methods.The examination of diaphragms from 31 592 grain-fed swine re­vealed an incidenoe of only 0.17 peroent. The incidenoe or!. sEiralis in dogs and oats is 9.8 and 5.7 peroent l respeotively.

The exam1nation of 41 697 speoimens from 44 speoies of Iowawildlife has thus far shown nine speoies to be reservoirs of'1'. s;piralis. These speoies are: rat .. fox" mink.. raccoon .. opossum..striped skunk,. spotted skunk, ooyote, and badger. In order todetermine the possible role of wildlife in perpetuat1pg trieb-1niasis in grain-fed swine, two modes of transmission have beenoonsidered: (direot oonsumption ot infected oaroasses by swine ..and (2) teoal,.transmissicn from infeoted animals to swine. Ex­perimental results ind:1 cate both modes ot 'transmitting theparasite may be important.

*Th18 1nvest1gat1on was supported 1n par' b7 a researchgrant 1606 (04), trom tho National InB~1tut. of Health, U. S.Pub110 Health S.~v1oe.

23

THE CURRENT STATUS OF LEPTOSPIROSIS IN THE UNITED STATES

A. H. Quin

On a world-wide basis, Bome forty speoies of pathogenioleptospiras with additional BUbtypes, as yet, not too clearlyidentified Berologioall~are responsible for disease in a widerange of animal hosts inoluding man.

These microorganisms, essentially saprophytic and aqua­phtlic in nature, are transmitted to other mammalian hosts bya long list of rodents. Several species of rats are primaryreservoirs of Leptospira ioterohemorrhagiae,the specific patho­gen of Weil's disease.

Specific diagnosis of clinical leptospirosis has proveddifficult for it requires special mioroscopio and stainingapproaches and the septicemic phase is transient. A risingblood titer as indicated by aocepted serological technios withselective antigens is a specific indication of active infeotionin cases where isolation of the micro-organism in oulture orlaboratory animal inoculations have not been accomplished.

Broad scale serological surveys indicate that L. Pomonais the predominant pathogen responsible for livestocK lepto­spirosis in the United states, while L. canioola and ictero­hermorrhaiiaeare the etiologioal faotorial canine leptospirosis.Low dl1ut on titers indicate that L. s~J[92' b~ll~ autumna~i6and ir1EBO~hOSa may also oarry as yet undetermined epizo6tlosign f1-eance for livestock as well as human hosts. However, sofar as livestock is concerned the epizootic significance ofspeoies other than L. ,omona must await more data based on(serological diagnosis coupled with isolation and specifioidentification of involved serotypes.

Whether in 'rodent hosts, domestic animals or man, lepto­spirosis may range from inapparent infeotion to a highly fatalfebrile illness. For this reason, it is probable that a greatmajority of cases involVing domestic animals or man are notdiagnosed. The current availabili~y of selective rapid type,formalin kille~ diagnostic antigens should oontribute materiallyto solving this problem.

Control of L. pomona leptospirosis of livestock aa wellaa L. canicols and icterofiemorrhagiae lep~ospirosi6 of dogs haabeen expedited by development of specific bacterial vaocineswhich confer an adequate measure of protection against fieldexposure.

24

ANTIGENIC VARIABILITY OF LEPTOSPIFAL SEROTYFES

RobeI'.lt M. Pike

As a possible means of obtaLn1ng serologic variant~ ofleptospirae, oultures were repea~edly transferred in medium con­taining homologous immune rabbit serum. In high concentrationsor immune serum growth was inhibited but in lower ooncentrations,although many of the organisms agglutinated, Borne remained freeand motile. Subcultures of the unagglutinated leptospirae atfirst showed the same serologic cha~dcteristics aa the parentcultures. After ten or more transfers at intervals of about amonth reduced agglutinability became apparent. After 37 transfersL. griP~ottthOSa agglutinated to a titer of 40 as compared to a~iter 0 4~960 for ~e parent strain. Evidence that the alteredstrain had also ,acquired new antigenio components was providedby its ability to induce the production of antibodies whioh werenot absorbed by the parent strain. L. pomona and, to a lesserextent, L. canicola also showed reduced agglutinability afterprolongea growth in the presence of homologous immune serum.The altered strain of ~. ~riPpottehOSa has showed no tendenoyto revertto the original parent ype over a period of 15 monthsin the absence of immune serum. It is suggested that comparable~ntigenio changes may occur under natural conditions.

25

THE HL REACTION AND ITS USE IN THE SEROLOGY OF LEPTOSPIROSIS

C. D. Cox

Increased interest in leptospirosis has directed attentionto the need for a safe genus-specific serologic test, thatCQuld be readily performed by the usual diagnos.ic or publichealth laboratory. In 1955 a report from this laboratory des­cribed a hemolytic (HL) reaction, which involved the abilityof leptospiral extracts to sensitize sheep erythrocytes tohemolysis in the presence of leptospiral antiserum and comple­ment. These extracts were similar in prQparatiQn to thosepreviously reported by Chang and McComb in 1954, who describedtheir use in a hemagglutination test with human erythrocytes.The HL procedure was shown to be broadly specific, in sharpcontrast to the high degree of type-speeific1ty seen in conven­tional agglutination or agglutination-lysis (AL tests)~ Subse­quent reports last year described the preparation, standardiza­tion, and stabilization of the antigen from the so-called non­pathogenic L~ biflexa.

Data are presented which describes the evaluation of theHL reaction with serotype speific rabbit antisera, with serafrom 190 proved human cases of leptospirosis, with sera frompre-and post-infected dogs and cattle, and wiuh sera fromrandomly selected cattle. The HL reaction would seem to warrantserious consideration as a routine serologic p~ocedure in thediagnosis and epidemiology of human lepuospirosis. The evidenceindicates that it may also prove to be' of value in serodiagnosisof canine and bovine leptospirosis; at least further studiesof its possible use would seem to be justified.

---- -- ~~------ --------

26

A SEROLOGIC SURVEY OF LEP~OSPIROSIS IN A NON-SELECTGROUP OF HOSPITAL PATIENTS AND IN PACKINGHOUSE WORKERS

N. GJ. J~ r

MillerBence

A total of 761 serum s~mplE1s were. ex.amined for leptospiralantibodies~ Five hundred and twenty-eight samples were obtainedfrom patients in variOus Omaha hospitals ~epresenting both anurban and a rural population~ These patients ij:~1;1e referred hereas the non-select group since serums were submitted for variousserologic examinations other than leptospiral~ In addition,SQrums from 233 packinghouse workers representing a specificoccupational group we~e obtained~

L~p~osEira icJ.;erohaemo11.rh~?-ae, ~e~.tospil-'a ~.icola and~OSE1rf E.,0Iona wer.e uSf5U as an'cigens iihrougEOu"t tEis st:udy.

~ ese-par ·leu ar serotypes were selected because they are stillconsidered the prima,J:'Y' i:r.:fecting type str·ains in the Unitedstates. The serotypes we~e'g~own in a fluid medium slightlymodified from that ,originally described by Stuart. The serologicexamination of all ser..:m samples was ca!~ried out by means ofthe agglutination-lysis test using darkfield illumination~

Seven, or 1_·3%, of the 528 serums fl....om the non-selectgroup of hospital patients demonstrated a titer for leptospiralantibodies. Four were posi·(.;ive for L. pornona and three for L..icterohaemorrhagiae~ No :r"eaction was s'een-WTJch the L* canico1.aantigen and none o'f the t1teras in this groups were grea"t·er"tnanl~:;lOO.

Of the serums fl"orrl ths 233 packinghouse 'VlTorkers, 15, or 6 c 4%,were positive at a titer of 1:30 or greater~ It is of particularinterest that all of the 15 serums were positive for L, ~omona.

Two serum samples demons,t:tl;a"tGd titers of- an active infecjion.Successive serum samples from one of the 'two samples demonstrateda definite increase of IJ.,. pomona antibodies. This patient alsoshowed clinical sympt;orr;S cnaI'aeteristic of L't pomona infection",

...-. P.,

These results indicat~e a 1'"Aath~;r4 low incidence of infect;;ionwith the three more Gommon leptospira in a general populationrepresented here by the non-select group of hospital patients (,This 1s particularly t~;le -'''Then this g!~OUP is compared with aspecific occupational group such as the packinghouse workers~

Since both cattle and hogs may become healthy ca:t"'lriers of Lf'pomona, an increase of positive reactors to this serotype Tnpaafinghouse workers is not too surp!~lsing. Again, the obviousconclusion must be reached that the majority of leptospiral infec~

tlo.ns are the result of occupational hazards ,.'

27

THE PLATE AGGLUTINATION TEST FOR THESERODIAGNOSIS-OF LEPTOSPIROSIS*

A. H. Killinger~ M. B. Hays, and M. F. Coria

The plate agglutination test for the serodiagnosis ofleptospirosis was developed by Dr•. H. G. stoenner. Antigenused in the test is a ohemically-killed, stable, refined, oon­oentrated and standardized suspension of leptospira.

In the preliminary soreen test one loopful (0.005ml) ofserum is mixed with one drop of antigen on a glass plate. Afterincubation and rotation, agglutination is visible around themargin of the drop. In positive samples the titer of the serumshould be determined by a rapid plate dilution test.

The general interpretation of the results of the test isas follows;

1. Negative plate soreen -- negative.

2. Positive plate screen. Positive rapid plate indilutions of 1:10 to 1;40 --

a) Low level of antibody againsii leptosp1ra

b) Cross reaction with another serotype of leptospira

c) Non-specific reaction

d) Vaccination

3~ Positive plate screen. Positive rapid plate indilutj;ons o:r 11160 or higher. -- Possible presentor past 1n£ection with speoifio leptospira.

*For a complete discussion of this technique, referenceis made to the Fort Dodge Bio-Chemio Review, 26:3 (1956) entitled"Leptospirosis Diagnosis, A Single MacroscopiC AgglutinationTest."

28

LEPTOSPIROSIS - NATURE OF THE INFECTION IN ANIMALS

J. E. Mosler

LeptospirosiS of the domestic animals in the United stateshas been recognized as a serious problem within the last decade.Various~rological surveys have adequately demonstrated the1mportance of this disease in both large and small animals. Theprinoipal leptospires produoing the disease in the United statesare L. ioterohemorrhagiaeJ L. canicola and L. pomona. Reoentsurveys have revealed 81gni?icant evidence of other serotypes.

Infected animals shedding the leptospiras via the urineserve as the primary source of infection to susoeptible animals.

The clinical manifestations of leptospirosis in animals areextremely variable even within a specific speeies. ~ical casesdevelop symptoms after an incubation period of 5-18 days. Duringthe early stages of the disease, the leptospiremia will be char­aoterized by rever~ lassitude" anorexia and'tissue damange, parti­oularly hemorrhage, and associated symptons.

The septicemia may last from 2-7 days and upon the appear­ance of leptospiral antibodies the 'organisms tend to disappearfrom the blood stream and localize 1nthe kidney t1Bauewherethey multiply and are excreted in the urine.

Various forms or the diseaae are noted and may be dividedinto sub-e11n1ca1 7 nemorrhagic, icterio, olassical, and chronicdepending on the subjective symptoms.

Among cattle hemoglobinuria, atypical noninflammatorymastitis and abortions are suggestive of leptospirosis.

The disease in swine may be relatively benign except forits effects on pregnant sows where abortions and high incidenceof mortality of the newborn are characteristio. In the horsethere is eVidence that leptospirosis might be associated withrecurrent iridocyclitis.

Broom very aptly described leptospirosis of the caninewhen he stated that the clinical manifestations might be absent,latent, sub-clinical, typioal, mild or severe. The most frequentsequel to leptospirosi~ in the dog is chronio interstitialnephritis and subsequent uremia which appear months or evenyears after the aoute infection.

29

THE CONTROL OF LEPTOSPIROSIS IN DOMESTIC ANIMALS

A.. L? Brown

The control of leptospirosis begins with an understandingof how it is spread~ At some time during the course of any lepto~

spiral infection, a leptospiremia exists and leptospira may beisolated from any organ~ This stage ends when antibodies areformed and if by this time the leptospira are not located withinthe kidney tUbules, the disease is self limiting $ While it is .customarily stated that leptospiral infections are accompaniedby the development of chronic interstitial nephritis, the lepto­spira are not located within the kidney tissue~ The organismsform tangled masses within the secondary convoluted tu"bt.ll.es whi.chmight be considered as bacterial colonies. From these masses,leptospira are shed into the urine for a period of from severalweeks to a lifetime... During their presence in the tubules, theleptospira stimulate a lowgrade inflammatory reaction in theinterstitial tissues which results in a oomparatively slow butprogressive chronic nephritis»

Leptospira shed in the urine are the most usual source ofnew infections~ New infections may be d$rived both through directcontact with animals shedding leptospira or indirectly throughcontaminated environment~ Leptospirosis spread by direct contactmay spread slowly through a group of animals thereby makingdiagnosis difficult~ Under conditions where the number of lepto­spira in surface water is able to build up, explosive outbreaksof leptospirosis are noted.

There has been an increased incidence of leptospirosis dueto L. pomona in cattle and swine in this state during the past18 mon~hs, particularly in northeast and southeast sections wherethere has been flooding in 1957 and 1958. Information obtainedrrom plate agglutination tests show an increase in reactor herdsduring this period since the end of the drought in 1957~ Thisincrease may be roughly correlated with rainfall and flooding~

There 1s no evidence that wildlife play an important part in thetransmission of Leptospira Eomona,in this state.

The use of Leptospira pomona Bacterin is the most reliablemethod for controlling infection in swine and cattle. The bacterinis effective because it may be used on any age animal, producerapid and long-lasting immunity and is~able in the liquid form~

Some suggested uses for this product are as follows: To checkthe spread of leptospirosis in a herd or drove following diagnosis,to protect animals in herds adjoining infected herds or along acommon water shed, to protect susceptible animals before introduc­tion into herds or areas which are contaminated, to protect animalstaken to shows and returned to herd, and to protect cattle infeeder lots especially when pigs and cattle are fed together.

30

Antiserum for the protection of dogs against L 4f canicolais available in combination with anti-canine dist5mper serum andanti-canine hepatitis serum. It is very effective in the usualdosage of 0 0 5 ml per pound Gf body weight if given previous toexposure. An experimen'tt was presented to emphasize its effective­n,ss@

~

Antibiotics have been found reasonably affective in eliminat­ing the carrier state but are of dubious value in modifying the~0trse of disease. The anti~iot1cs that have been found most effec­tive are thoseelimina'bed tb.rough the kidn.ys in a high concentra­tion ov~r an extended period of time. Inoluded in this group .fant1blGties are the tetracyolines and straptomycin~

The author wishes to thank Dr. Daniel Waring, Dr~ Milo Johnsonand Mr. Robert Cumings of ~he state and Federal Brucellosis Labora­tQry, Lincoln, Nebraska for use of their data on the incidence ofleptospirosis in Nebraska.

31

DIAGNOSIS ~ EPIDEMIOLOGY AND TREA'rlVIENT OF HUMAN STAPIIYLOCOCCALDISEASE WITH SOME CONSIDEHATION O}1' THE DISEASE IN ANIMALS

I. M. Smith, M. E. Godfrey, and A. P. Wilson

Although staphylooocci can be differentiated by their pigmentor coagulase productio~ this does not allow a precise enough diag­nosis for epidemiological purposes. Strain differences and similari­ties are best studiea by phage typing with 24 or more standardphages. The virulence of staphylococci is at present difficultto assess. One of the reasons for this is that the same numberof cocci injected into experimental animals by different routeswill kill rapidly in one case and will m~rely result in temporaryindisposition in a second.

In hospital nasal carriers of staphylococci are more commonthan in the general population. Phage typing studies show that29% of the total hospital staphylococoal infections are caused .by one type, namely type 81. Twenty-seven per cent of the staffoarry this strain but more importantly 57% of staphylococcal skinsepsis in the staff is caused by this strain.

In the family a virtual plague of boils may make the roundsover a period of months or years. Approximately 50% of the membersof such families are nasal carriers of the strain causing these ~furuncles. In some cases the strain was introduced from a hospitalby a physician or nurse member of the family.

The types of infeotion caused in man range from boils andcarbuncles to necrotizing hemorrhagic pneumonia and septicemia.Many of these diseases are acquired in the hospital, frequentlywhen the patient is debilitated from other causes.

Control of the disease consists in breaking the chain ofinfeotion. Patients dripping pus must be isolated. Physiciansand nurses must return to reasonable standards of asepsis andstaphylococcal diseases must be treated early and adequately.

These organisms are known to cause a var1ety of akin d1seases,mastitis, enteritis and septicemia in a number of animal species.In birds, dermatitis and staphylocoocos1s occur. It is notknown whether a closed circuit of staphylococcal infection ispresent in animals or whether in truth, these are diseases ofman transmissable to aninals.

Treatment is unfortunately not predictable but there is agroup of SUitable drugs from which a choioe can be made. If theorganism is susceptible the drugs of choice are in order of prefer­ence~ penioillin, streptomycin, erythromycin, novobiocin, chloram­phenicol, oleandomycin or the tetracyclines. Vancomycin and risto­cetin are reserved for severe infections and baciteracin, neomycin,tyrooidin or the furacins for local treatment.

32

RABIES - THE EPIDEMIOLOGIC PATTERN

stanley L. Hendricks and I. II. Borts

The reported incidence of rap,ies in dogs in the United stateshas decreased in the laat decade but the disease in other animals,principally wildlife, bas rem.a1ne d at a high level. In a group ofseleoted states (Minnesota, Iowa, Missouri, Kansas, Nebraska, SouthDakota and North.,Dakota) this trend is more marked. In thesestates about one-half of all rabies cases reported are wild animals.Sk nks constitute 84% of the wild ani~l oases. In contrast65~ of the wild animal rabies reported in the United states isamong the fox population. or 5,698 animal heads examined at thestate Hygienic Laboratory over a 20 year period 1,558 or 27.3%were positive for rabies. The per cent of positives varied con­siderably among different species of animals. Of all the headsthat were positive 17.1% we~e Negri negative but mouse positive.This too, varied greatly w'1th species. Til€1:=.te 'W'er'e 4,184 micro­scopic negatives of whioh 26'7 or 6. 3% weI"~ pos!tive by mouseinocuJa t1on.

if

33

THE PATHOGENESIS OF RABIES IN INSECTIVOnOUS BATS

s. Edward Sulkin

Preliminary experiments (Sulkin at aI, Proo. Soc. Exper.Biol. Mad. 96:461, 1957) have indioateatlUi't tfie interscapularbrown~ of the Mexican free-tailed bat may constitute a targetorgan in which virus may persist for long periods of time. Theseexperiments have now been extended to include experiences withthe little brown bat, Myofis luclfuguB, a true hibernator, inaddition to the Mexican r~ee-~al1ed~at, Tadarida mexicana, aquasi hibernator. Hibernation delays s1gnir1can£ly multiplioationof the virus inoculated intramusoularly or into the surgicallyexposed interscapular brown fat and provides a means fur II coldstorage" of the rabies virus under natural oirouMstances. Thestudy would Beem to support the proposition that brown fat whichprovides food reserve during the inactive state may also providemeans for storage of the virus during the period of latency.Environmental temperature has a profound effect on the progressof experimental rabies in bats. Both the virus and the hoatremain quiescent when maintained in the cold and both are activatedwhen the animal is transferred to a warm environment.

34

AVIAN T'lJBEHCLE BAC::'-.LLUS INFEC1I'ION IN rrLAU

Alfr·:.1d (} Kclr'lson

In the United states the greatest incidence of avian tuber­culosis in the North Central area, where in some 10oo1i ties halfof the chicken flocks harbor the dif?ease. The infection ,rata mayvary from 10 to 25 per cent in flocks of hens 2 years of age andolder.

Mycobacterium avium grows in 10 to 14 days on egg-medium toform'small, mols~~ smootn,'rounded, buff-colored colonies~ They

"are relatively resistant in vitro to streptomycin, to para­aminosalicylic acid and to isoniazid. Avian t,ubercle bacilliare identified by their ability to cause progressive disease inrabbits and chickens and by their failure to do so in guinea pigs.There is partial cross-sensitivity with mammalian tubercle bac1l1i~with Mycobaoterium Earatuberculosis, with some unidentifiedaCid-fast bacterta.

Avian tuberculosis is found in many kinds of domestic fowl;in wild birds, and in exo~ic avian species in zoological parks~

Naturally occurring infection is found in swine, cattle~ sheep,mink, rabbits, and-~rarely--horses and goats. Guiaea pigs arQhighly resistant and dogs and cats apparently are immune ... Inthis country almost all tuberculosis in sw:1.ne is of avian origin.In 1956 approximately 5 per cent of all swin& slaughtered in theUnited states had tuberculous lesions. Cattle with avian tuber­culosis may react to the routine test for bovine tuberculosis.

It is apparent that man is relatively resistant to infectionwith Mioobacterium avium. In only about 30 recorded cases of1.nfect on in. man lias tE.e" microorganism been identifled adequately.Four cases will be described here. In each, the acid-fast bacilliwere of interest originally because they did not appear to behuman or bovine tubercle bacillj.. They we~e found to have thecultural and pathogenic properties of avian tuber"cle bacilli o

They were agglutinated by serum from tuberculous chickens andthey induced sensitivity to avian tuberculin in guinea pigs.

Case 1., --A 22-mon'bh old child with a low-grade re.spiratoryillness" or a few months t duration was found to have diffuse in­filtration of the right upper pulmonary lobe. Bronchoscopicwashings contained acid-fast bacilli. One culture of gastricwashings presented colonies of acid-fast ~acil11 which provedto be avian tuoercle bacilli. The patient's reaction to aviantuberculin was more pronounced than her' react ion to PPD *' Sheremained free of symptoms thl"J'ough 9 months of hospital care,during which time the pulmonary infiltr4ate gradully cleared ..The child caIne from a Minneso"ba farm where 50 per cent of 400chiokens were found to reaot to avian tuberculin.

35

Case 2.-- A 57-year old Iowa farm woman oame to the clinicfor otner reasons but incidentally complained of a fluctuatingswelling of the right index finger which had persisted foraa year.This was incised and granulo~~ua t,issue was removed. A pathologiodiagnosis of tuberculouB synovitis was made. Avian tuberclebacilli were cultured from the ,material. Treatment with isoniazidand para-aminosalicylic aoid'was given fo~ 8 weeks but, was dis­continued when the micro-organism was ident·lfled. An uneventfulreoovery and complete return of function of the hand was achieved.

Case 3.--A 59-year old man with severe' oardiac and pulmonaryembarrassnlent had a bistory compatible with' silicosis and hadbeen a tool grinder in a rural town in Ohio.. Thoracic roentgeno­grams revealed extensiva bilat'eral £ibroBi,B '. Avlan tuberolebacilli were isolated in cultures of thre~~6peoimens of sputumand one of gastric washing. The pa~1ent. died 0'£ cardiac ·failure.Seotions of lung presented fibrosis with birefringent crystals.One section showed a small focus of necr.oS.1s with aCid-fast baoilli.

Case, 4.--A 64 year old granite worker, a lifelong residentof Minneso~a, gave a history of "having lupg trouble 'for a longtime." Thoracic roentgenograms revealed pulmonary fibrosisoompatible with silicosis, Repe~t~d oultures of gastrio wash1~gs

and of aputumccontained ao1d-faav bao~111.ident1fiedas avaintubercle bacilli. This patient.. gave a pronounoed reaction toavian tuberculin as well as PPD.. His sQ~m agglutinated his ownas well as other strains of avian ,tubercle. bacilli..•

It is of special inte~~8btfiat th. last two patients hadsilicosis, in view of the well-knOwn obs,e~va.tion tta t certainavirulent strains of tUbeJ;'o~e,l bacilli sUO.h aa BeG and H37Rv oancause progressive disease in silioot:1c b'tJ,'b not in 'normal gU,ineapigs.

It is likely that infeotion With avian tuberole bacilli1s more common in man than reports indlca'te. Failure to disol,osesuch infeotions may be' due to the relatively high resistance ofguinea pigs, which are the animals oommonly uaed1n ·the diagnosiSof tuberoulosis. AlSO, it is possible that in Borne laboratoriesworkers are not acquainted With the cultur~l characters andmethods of identifying Mycoba~:terium avium•.

36

SOME MODIFICATIONS OF MYCOBACTERIA EFFECTED WITH ENZYMES

Warren Eo Engelhard

A procedure was developed for investigating modifications ofvirulent mycobacteria with enzymes without marked reduction ofcell numbers. Routine indexes for cellular alterations included;rapid reduction of methylene blue dye (Thunberg technique); failureto bind the neutral red dye and cell dispersement as observedmicroscopically. Other manifestations of alteration observedincluded change in growth and staining characteristics and abilityto absorb mercuric ions.

Mycobacteria fulfilling the above indexes were used first forphysioligical studieso It was shown that with enzyme treated washedcells oxygen consumption was considerably greater when the sub­strates lactate, pyruvic acid, glucose and acetic acid were comparedwith non-treated cells. Similar results were shown with substratesisocitric, "malic and fumaric acid. Less marked, but neverthelessincreased stimulation was observed with cisaconitic, citric andsuccinic acid. Warburg studies with sonorated cell-free extractswith various coenzymes confirmed the presence of the above enzymes.Potentiation of antibiotic activity in the presence of trypsin wasshown. Trypsin was observed to have an opsonic effect on virulenttubercle cells when tested with rabbit macrophages.

To identify some of the cellular components removed by enzymeaction, amino acid analysis was completed chromatographically. Atotal of 17 amino acids were identified in the supernatents of enzymetreated cells: Alanine, arginine, aspartic acid, cystine, glycine,histidine, isoleucine, leucine, lysine, methionine, proline, phenyl­alanine, threonine, tyrosine, valine, tryptophane and serine.Fourteen of these, all except arginine, lysine and tyrosine, wereshared in lesser amounts with the enzyme itself o Quantative workto uncover these is necessarYe For confirmation of above cell wallamino acids fairly pure cell wall preparation was necessary. Heattreatment, sonoration and Miele disintegration were used. Limitedobservations of electron micrographs revealed sonoration providedthe most satisfactory cell wall preparationso

':17.J

RECENT ADVANCES IN KNOWLEDGE OF WESTERN EQUINEENCEPHALOMYELITIS AND ST. LOUIS ENCEPHALITIS

Preston Holden

Although the major factors in the natural histories of Vl8sternequine encephalomyelitis (WEE) and st& Louis encephalitis (SLE)have been known si.nce the early 1940's, there is oonsiderable needfor continued research c This need exists because adequate methodsfor preventing spread of the infections to man have not yet beendevised.

Indispensible to control of encephalitis is the specificidentification of important vectors and hosts~ It is known thatboth WEE and SLE viruses in rural areas of the west are transmi.ttedchiefly by the mosquito Culex tarsalis. !n urban areas of the east,SLE virus is transmitteamamly by tITe Culex p2-£.1ens .camp] ex • Therelative importance of different bird species as hosts of the virusesj s unknownr, Certain leads, however, have baen obtained" Theoreti­cally, the species should be abundantly dist,ributed in affectedareas.; they should be available in a quiescent state during theperiod of peak biting activity for the vectors; and their breedingse·ason should extend well into the summer since nestling birds aremore vulnerable than adults to attack by mosquitoes~

Envtronmental factors that are important in the transmissionof vlEE and SLE viruses include climatic factors which are favorableto the production and longevity of birds and mosquitoes~ Also ofimportance are certain man-made factors, such as agricultural prac­tices and the urbanization of communities, which also' influencefavorably the breeding of mosquitoes~ Large numbers of cattle orother dead-end hosts may compete with birds as sources of blood forthe vectors and thereby exert a suppressing effect on virus trans­mission,

Evidence has been obtained that WEE virus may survive thewin~er in Californ:la in adult mosquitoes and/or as latent infec-·tiona in birds~ No evidence has been obtained that the virusesare brought into the country by birds migrating from more southernareas.

Important advances in laboratory mathodology include thedevelopment of a hemagglutination inhibition test for detectingserum antibodies and a tissue culture procedure for virus isolationattempts~

Trends for future studies should be directed toward devisj.ngbetter methods of control. It is believed that the following possi­bilities should be investigated: (a) Is pre~epizootic control of

38

encephalitis areas a practicable concept? (b) Can a satisfaotoryvacoine be developed for use in man and l if SOl would it receiveaooeptance by the public? (0) Can more effective inseoticides bedeveloped? (d) Which species of birds or other vertebrates areessential to survival of the viruses? and (e) Can enoephalitisepidemics be predicted suffioiently in advanoe of onset to permittheir prevention through prompt action by publio health offioials?

39

PARTICIPANTS

BACON, MARION, Ph.D., Assistant Professor, Department of Microbiology, Collegeof Medicine, University of Nebraska, Omaha, Nebraska

BaRTS, I. H., M.D., Director, State Hygienic Laboratory, Iowa City, Iowa

BRAUN, JOHN L., B.S., Field Epidemiologist, Institute of Agricultural Medicine,State University of Iowa, Iowa City, Iowa

BROWN, ALBERT L., Ph.D., Biological Research, Norden Laboratories, Lincoln,Nebraska.

COX, CHARLES D., Ph.D., Professor and Chairman, Department of Microbiologyand Public Health, University of South Dakota, Vermillion, South Dakota

ENGELHARD, WARREN E., Ph.D., Associate Professor, Department of Bacteriology,University of Nebraska, Lincoln, Nebraska

GRIFFITHS, HENRY J., D.V.M., Ph.D., Professor, Department of VeterinaryPathology and Parasitology, College of Veterinary Medicine, University ofMinnesota, St. Paul, Minnesota

HENDRICKS, STANLEY L., D.V.M., Public Health Veterinarian, Iowa State Departmentof Health, Des Moines, Iowa

HOLDEN, PRESTON, D.V.M., Dr. PH, Chief, Virology Unit, Encephalitis Section,U.S. Department of Health, Education and Welfare, Greeley, Colorado

KARLSON, ALFRED G., D.V.M., Ph.D., Section of Bacteriology, Mayo Clinic,Rochester, Minnesota

KILLINGER, ARDEN H., Ph.D., Director, Biological Product Development, FortDodge Laboratories, Fort Dodge, Iowa

MILLER, NORMAN G., Ph.D., Assistant Professor, Department of Microbiology,College of Medicine, University of Nebraska, Omaha, Nebraska

MORRISON, SUMNER M., Ph.D., Professor, Department of Pathology and BacteriologyCollege of Veterinary Medicine, Colorado State University, Fort Collins,Colorado

MOSIER) J. E., D.V.M., Professor, Department of Surgery and Medicine, Schoolof Veterinary Medicine, Kansas State .College, Manhattan, Kansas

PIKE, ROBERT M., Ph.D., Professor, Department of MQcrobiology, SouthwesternMedical School, University of Texas, Dallas, Texas

40

QUIN, A.H., D.V.M~, Vice-President, Jensen-Salsbery Laboratories, Inc.Kansas City, Missouri

RADCLIFFE, C.E., M.D., Associate Professor, Department of Dermatology,University Hospitals, State University of Iowa, Iowa City, Iowa

SMITH, IAN M., M.D., Department of Internal Medicine, University Hospitals,State University of Iowa, Iowa City, Iowa

STEELE, JAMES H., D.V.M., M.P.H., Chief, Veterinary Public Health CommunicableDisease Center, U.S. Department of Health, Education and Welfare, Atlanta,Georgia

SULKn~, S. EDWARD, Ph.D., Professor and Chairman, Department of Microbiology,Southwestern Medical School, University of Texas, Dallas, Texas

TJALMA, RICHARD A•., D. V•M, Institute of Agriculture and Medicine, College ofMedicine, State University of Iowa, Iowa City, Iowa

YOUNG, GEORGE A., D.V.M., Professor and Chairman, Department of AnimalPathology and Hygiene, University of Nebraska, College of Agriculture,Lincoln, Nebraska

ZIMMERMAN, WILLIAM J., Ph.D., Associate Professor, Veterinary Medical ResearchInstitute, Iowa State College, Ames, Iowa