prrs y aujezky

Biosecurity, Control and Biosecurity, Control and Eradication Strategies Eradication Strategies for PRRS and Aujesky’s for PRRS and Aujesky’s

DiseaseDisease

Steve Henry, DVM, Dipl ABVPSteve Henry, DVM, Dipl ABVP

Abilene Animal Hospital, P.A.Abilene Animal Hospital, P.A.

Abilene, KSAbilene, KS

AMVEC XXXVII Congreso Nacional

July 18, 2002

Puerto Vallarta, Mexico

PRRS and Aujesky’s PRRS and Aujesky’s infectionsinfections

►Are prevalent and costly diseases of Are prevalent and costly diseases of swineswine

►Can be successfully managed only Can be successfully managed only with systematic plans and coordinated with systematic plans and coordinated veterinary strategiesveterinary strategies



►Can be successfully managed only Can be successfully managed only with systematic plans and coordinated with systematic plans and coordinated veterinary strategiesveterinary strategies BiosecurityBiosecurity – to prevent any movement of – to prevent any movement of

virus between groups or farmsvirus between groups or farms




virus between groups or farmsvirus between groups or farms ControlControl – to minimize the damage done by – to minimize the damage done by

the virus in infected farmsthe virus in infected farms




virus between groups or farmsvirus between groups or farms ControlControl – to minimize the damage done by – to minimize the damage done by

the virus in infected farmsthe virus in infected farms EradicationEradication – to ultimately remove the – to ultimately remove the

virus from farms and regionsvirus from farms and regions

Biosecurity – the primary Biosecurity – the primary strategystrategy

►The security system which prevents The security system which prevents the entry of new virus infections into the entry of new virus infections into unaffected herds (or new strains into unaffected herds (or new strains into infected PRRS herds)infected PRRS herds)


►The security system which prevents The security system which prevents the entry of new virus infections into the entry of new virus infections into unaffected herds (or new strains into unaffected herds (or new strains into infected PRRS herds)infected PRRS herds)

►Transmission of virus from one Transmission of virus from one premise to another is primarily by way premise to another is primarily by way of live animals or transported body of live animals or transported body fluids fluids


►The security system which prevents the The security system which prevents the entry of new virus infections into entry of new virus infections into unaffected herds (or new strains into unaffected herds (or new strains into infected PRRS herds)infected PRRS herds)

► Transmission of virus from one premise Transmission of virus from one premise to another is primarily by way of live to another is primarily by way of live animals or transported body fluids animals or transported body fluids

►Hygiene failures have repeatedly been Hygiene failures have repeatedly been shown as the reason virus is introducedshown as the reason virus is introduced

The many questions - How The many questions - How “good” must biosecurity be if we “good” must biosecurity be if we

are confident it is adequate?are confident it is adequate?



►Shower in and out of facilities?Shower in and out of facilities?



►Shower in and out of facilities?Shower in and out of facilities?►Personnel or veterinary down-times Personnel or veterinary down-times

between groups or farms?between groups or farms?




between groups or farms?between groups or farms?►What amount of cleaning for facilities What amount of cleaning for facilities

between groups or repopulation?between groups or repopulation?




between groups or farms?between groups or farms?►What amount of cleaning for facilities What amount of cleaning for facilities

between groups or repopulation?between groups or repopulation?►How long must facilities be empty How long must facilities be empty

between groups?between groups?

Biosecurity – key veterinary Biosecurity – key veterinary considerations for PRRS and PRVconsiderations for PRRS and PRV

Biosecurity – key veterinary Biosecurity – key veterinary considerations for PRRS and PRVconsiderations for PRRS and PRV►Potential vectors that must be Potential vectors that must be

systematically controlled for both systematically controlled for both diseases include:diseases include:


systematically controlled for both systematically controlled for both diseases include:diseases include: Animal movement and knowledge of disease Animal movement and knowledge of disease

statusstatus



statusstatus Transportation personnel and equipmentTransportation personnel and equipment



statusstatus Transportation personnel and equipmentTransportation personnel and equipment Caretaker and service personnel hygieneCaretaker and service personnel hygiene



statusstatus Transportation personnel and equipmentTransportation personnel and equipment Caretaker and service personnel hygieneCaretaker and service personnel hygiene Animal care equipmentAnimal care equipment




►Facility cleanliness and disinfection Facility cleanliness and disinfection systemsystem


systematically controlled for both diseases systematically controlled for both diseases include:include: Animal movement and knowledge of disease Animal movement and knowledge of disease


►Facility cleanliness and disinfection systemFacility cleanliness and disinfection system►Pig flow management – all outPig flow management – all out

Biosecurity – key veterinary Biosecurity – key veterinary considerations for PRRS and PRVconsiderations for PRRS and PRV►Potential vectors that must be systematically Potential vectors that must be systematically

controlled for both diseases include:controlled for both diseases include: Animal movement and knowledge of disease statusAnimal movement and knowledge of disease status Transportation personnel and equipmentTransportation personnel and equipment Caretaker and service personnel hygieneCaretaker and service personnel hygiene Animal care equipmentAnimal care equipment

►Facility cleanliness and disinfection systemFacility cleanliness and disinfection system►Pig flow management – all outPig flow management – all out► ““Managing the behavior of people at all times”Managing the behavior of people at all times”

ControlControl of PRRS and of PRRS and Aujesky’s disease requires a Aujesky’s disease requires a clear understanding of each clear understanding of each

virus, the behavior of the virus, the behavior of the virus in herds and the virus in herds and the immunology of these immunology of these

infections. infections.

Contrasting the PRRS and Aujesky’s Contrasting the PRRS and Aujesky’s virusesviruses

PRRSPRRS►Depends on long-Depends on long-

term viremia and term viremia and copious virus copious virus excretion in body excretion in body fluidsfluids

Aujesky’sAujesky’s


PRRSPRRS►Depends on long-Depends on long-

term viremia and term viremia and copious virus copious virus excretion in body excretion in body fluidsfluids

Aujesky’sAujesky’s► Short-term viremia Short-term viremia

but individuals are but individuals are latently infected, latently infected, infections infections recrudesce and recrudesce and animals again shed animals again shed virusvirus


PRRSPRRS► Depends on long-term Depends on long-term

viremia and copious viremia and copious virus excretion in virus excretion in body fluidsbody fluids

► Post-infection Post-infection immunity develops immunity develops slowly (weeks) but is slowly (weeks) but is long-lasting and long-lasting and “sterilizing” immunity “sterilizing” immunity for homologous for homologous strainsstrains


but individuals are but individuals are latently infected, latently infected, infections infections recrudesce and recrudesce and animals again shed animals again shed virusvirus


PRRSPRRS► Depends on long-term Depends on long-term

viremia and copious viremia and copious virus excretion in virus excretion in body fluidsbody fluids

► Post-infection Post-infection immunity develops immunity develops slowly (weeks) but is slowly (weeks) but is long-lasting and long-lasting and “sterilizing” immunity “sterilizing” immunity for homologous for homologous strainsstrains


but individuals are but individuals are latently infected, latently infected, infections recrudesce infections recrudesce and animals again and animals again shed virusshed virus

► Post-infection Post-infection immunity is short-immunity is short-lived and is not lived and is not “sterilizing” “sterilizing” immunityimmunity


PRRSPRRS► Virus mutates Virus mutates

rapidly with diverse rapidly with diverse genetic variantsgenetic variants





Aujesky’sAujesky’s► Virus is very stable Virus is very stable

and strain variation and strain variation is not importantis not important




►Herds may become Herds may become infected with infected with multiple variantsmultiple variants









► Immunity can Immunity can effectively prevent effectively prevent recrudescence recrudescence





► Immunity is not Immunity is not predictably cross predictably cross protectiveprotective








► Immunity is not Immunity is not predictably cross predictably cross protectiveprotective




► Immunity from Immunity from vaccination is vaccination is predictablepredictable


PRRSPRRS► Vaccines are not Vaccines are not

predictable, safe or predictable, safe or effective tools in effective tools in PRRS control PRRS control programsprograms




predictable, safe or predictable, safe or effective tools in effective tools in PRRS control PRRS control programsprograms

Aujesky’sAujesky’s► Vaccine is safe, Vaccine is safe,

effective and effective and essential to essential to successful control successful control and eradication and eradication programsprograms



predictable, safe or predictable, safe or effective tools in PRRS effective tools in PRRS control programscontrol programs

► Lack of “marker” Lack of “marker” vaccine technology vaccine technology makes it impossible to makes it impossible to differentiate immune differentiate immune response of field vs response of field vs vaccine infectionsvaccine infections


effective and effective and essential to essential to successful control successful control and eradication and eradication programsprograms



predictable, safe or predictable, safe or effective tools in PRRS effective tools in PRRS control programscontrol programs

► Lack of “marker” Lack of “marker” vaccine technology vaccine technology makes it impossible to makes it impossible to differentiate immune differentiate immune response of field vs response of field vs vaccine infectionsvaccine infections


effective and effective and essential to successful essential to successful control and control and eradication programseradication programs

► Vaccine “markers” Vaccine “markers” and differential and differential serologic tests serologic tests differentiate field differentiate field infection from infection from vaccinal immune vaccinal immune responseresponse

PRRS virus transmissionPRRS virus transmission


►Highly infectious virus, requiring few Highly infectious virus, requiring few particles to initiate infectionparticles to initiate infection



►Large quantities of virus are shed in Large quantities of virus are shed in most body fluids and excretions during most body fluids and excretions during viremiaviremia



►Large quantities of virus are shed in Large quantities of virus are shed in most body fluids and excretions during most body fluids and excretions during viremiaviremia

►Virus is NOT hardy outside the pig, Virus is NOT hardy outside the pig, does not persist in the environmentdoes not persist in the environment



►Large quantities of virus are shed in most Large quantities of virus are shed in most body fluids and excretions during viremiabody fluids and excretions during viremia

►Virus is NOT hardy outside the pig, does Virus is NOT hardy outside the pig, does not persist in the environmentnot persist in the environment

►Virus dies rapidly in decomposing tissue, Virus dies rapidly in decomposing tissue, thus autolyzed carcasses pose little riskthus autolyzed carcasses pose little risk

PRRS virus transmission – bad PRRS virus transmission – bad newsnews


► Semen contaminated with virus easily Semen contaminated with virus easily transmits virustransmits virus



► Injecting multiple pigs with the same needle Injecting multiple pigs with the same needle efficiently transmits PRRSefficiently transmits PRRS




►Mosquitoes and house flies have been Mosquitoes and house flies have been shown to be potential vectors (other insect shown to be potential vectors (other insect candidates?)candidates?)




► Mosquitoes and house flies have been shown Mosquitoes and house flies have been shown to be potential vectors (other insect to be potential vectors (other insect candidates?)candidates?)

► While generally fragile in the environment, While generally fragile in the environment, special circumstances (snowball survival) special circumstances (snowball survival) reinforce the need for clean, dry, disinfected reinforce the need for clean, dry, disinfected facilities and equipmentfacilities and equipment

PRRS virus transmission – good PRRS virus transmission – good newsnews


►Aerosol transmission is very hard to Aerosol transmission is very hard to document; distance between farms document; distance between farms seems effective as a barrierseems effective as a barrier



►Standard caretaker and worker Standard caretaker and worker hygiene, clean clothes and washing hygiene, clean clothes and washing hands, prevents transmissionhands, prevents transmission



►Standard caretaker and worker Standard caretaker and worker hygiene, clean clothes and washing hygiene, clean clothes and washing hands, prevents transmissionhands, prevents transmission

►Drying and disinfection are predictably Drying and disinfection are predictably effective in decontaminating facilitieseffective in decontaminating facilities



►Standard caretaker and worker hygiene, Standard caretaker and worker hygiene, clean clothes and washing hands, clean clothes and washing hands, prevents transmissionprevents transmission

►Drying and disinfection are predictably Drying and disinfection are predictably effective in decontaminating facilitieseffective in decontaminating facilities

►Other species are not infected with the Other species are not infected with the virusvirus

Aujesky’s transmission contrasted to Aujesky’s transmission contrasted to PRRSPRRS


►The potential for insect vectors is NOT The potential for insect vectors is NOT an issue with Aujesky’s an issue with Aujesky’s


►The potential for insect vectors is NOT The potential for insect vectors is NOT and issue with Aujesky’s and issue with Aujesky’s

►Aerosol or area spread IS an issue as Aerosol or area spread IS an issue as infected premises are a high risk to infected premises are a high risk to any others within 3kmany others within 3km



►Aerosol or area spread IS an issue as Aerosol or area spread IS an issue as infected premises are a high risk to infected premises are a high risk to any others within 3kmany others within 3km

►Other species are infected with Other species are infected with infected carcasses and meat meal infected carcasses and meat meal posing a riskposing a risk



►Aerosol or area spread IS an issue as Aerosol or area spread IS an issue as infected premises are a high risk to any infected premises are a high risk to any others within 3kmothers within 3km

►Other species are infected with infected Other species are infected with infected carcasses and meat meal posing a riskcarcasses and meat meal posing a risk

►Hygiene steps to prevent PRRS Hygiene steps to prevent PRRS transmission are effective against transmission are effective against Aujesky’sAujesky’s

EradicationEradication strategies have been strategies have been accepted and shown effective with accepted and shown effective with

Aujesky’s. Aujesky’s.

PRRS eradication efforts are limited, PRRS eradication efforts are limited, much is yet to learn but there is much is yet to learn but there is

success. Given the limited success. Given the limited effectiveness of control measures, effectiveness of control measures,

veterinarians will be heavily involved veterinarians will be heavily involved in PRRS eradication in the future. in PRRS eradication in the future.

Elimination of Aujesky’s Elimination of Aujesky’s infectioninfection


►Modified live, “marker” vaccines are the Modified live, “marker” vaccines are the critical tool in herd and regional elimination critical tool in herd and regional elimination



► Strict movement control procedures must be Strict movement control procedures must be clearly understood and enforcedclearly understood and enforced




► A systematic vaccination strategy, A systematic vaccination strategy, implemented and accomplished by all implemented and accomplished by all producers in the region, is mandatoryproducers in the region, is mandatory




► A systematic vaccination strategy, A systematic vaccination strategy, implemented and accomplished by all implemented and accomplished by all producers in the region, is mandatoryproducers in the region, is mandatory

► Systematic serology testing during and after Systematic serology testing during and after the elimination strategy, using differential the elimination strategy, using differential testing, determines progress of the testing, determines progress of the elimination effort.elimination effort.

Example of an Aujesky’s vaccination Example of an Aujesky’s vaccination strategy using G1 deleted marker strategy using G1 deleted marker

vaccinevaccine


vaccinevaccine► Breeding herd animalsBreeding herd animals

Entire herd vaccinated every 90 daysEntire herd vaccinated every 90 days ““Blanket” vaccination at one timeBlanket” vaccination at one time Repetition is critically important, being careful not Repetition is critically important, being careful not

to miss any animals, as immunity is short-livedto miss any animals, as immunity is short-lived


vaccinevaccine► Breeding herd animalsBreeding herd animals

Entire herd vaccinated every 90 daysEntire herd vaccinated every 90 days ““Blanket” vaccination at one timeBlanket” vaccination at one time Repetition is critically important, being careful not to Repetition is critically important, being careful not to

miss any animals, as immunity is short-livedmiss any animals, as immunity is short-lived

►Growing animals (maternal passive immunity Growing animals (maternal passive immunity issue)issue) All animals are vaccinated at 9 weeks of ageAll animals are vaccinated at 9 weeks of age A second dose is given at 13 weeks of ageA second dose is given at 13 weeks of age Intranasal vaccine alternative for nursing piglets can Intranasal vaccine alternative for nursing piglets can

replace the 9 week vaccinationreplace the 9 week vaccination

PRRS Eradication ProcessesPRRS Eradication Processes


►Dependant on naturally acquired, sterilizing Dependant on naturally acquired, sterilizing immunity in the breeding herdimmunity in the breeding herd



► From this immune sow herd the weaned From this immune sow herd the weaned pigs are free of viruspigs are free of virus




► Pigs are segregated from the sows at Pigs are segregated from the sows at weaning and are reared in a multi-site weaning and are reared in a multi-site systemsystem




► Pigs are segregated from the sows at Pigs are segregated from the sows at weaning and are reared in a multi-site weaning and are reared in a multi-site systemsystem

► Successfully done by breeding stock Successfully done by breeding stock companies, this approach is still being companies, this approach is still being explored in commercial herds and explored in commercial herds and production systemsproduction systems

PRRS eradication PRRS eradication considerationsconsiderations


►No vaccine is effective as is the case with No vaccine is effective as is the case with Aujesky’s; serologically mimics infectionAujesky’s; serologically mimics infection



► There is no serologic test to differentiate There is no serologic test to differentiate between vaccine and field infection between vaccine and field infection responsesresponses



► There is no serologic test to differentiate There is no serologic test to differentiate between vaccine and field infection between vaccine and field infection responsesresponses

► The testing tools, ELISA, IFA, SN, PCR all The testing tools, ELISA, IFA, SN, PCR all require careful coordination and require careful coordination and interpretationinterpretation



► There is no serologic test to differentiate There is no serologic test to differentiate between vaccine and field infection responsesbetween vaccine and field infection responses

► The testing tools, ELISA, IFA, SN, PCR all The testing tools, ELISA, IFA, SN, PCR all require careful coordination and interpretationrequire careful coordination and interpretation

►Negative “sentinel animals”, introduced to Negative “sentinel animals”, introduced to detect presence of virus, are a key component detect presence of virus, are a key component of the diagnostic sequence – this requires of the diagnostic sequence – this requires careful management and controlcareful management and control

ConclusionsConclusions


► Ultimately both PRRS and Aujesky’s diseases Ultimately both PRRS and Aujesky’s diseases must be eradicated if herds are to be must be eradicated if herds are to be successful economicallysuccessful economically


► Ultimately both PRRS and Aujesky’s diseases Ultimately both PRRS and Aujesky’s diseases must be eradicated if herds are to be must be eradicated if herds are to be successful economicallysuccessful economically

► The processes for eradication are technically The processes for eradication are technically challenging, and require consistent effort challenging, and require consistent effort and a great deal of sampling with careful and a great deal of sampling with careful interpretationinterpretation


► Ultimately both PRRS and Aujesky’s diseases Ultimately both PRRS and Aujesky’s diseases must be eradicated if herds are to be successful must be eradicated if herds are to be successful economicallyeconomically

► The processes for eradication are technically The processes for eradication are technically challenging, and require consistent effort and a challenging, and require consistent effort and a great deal of sampling with careful great deal of sampling with careful interpretationinterpretation

► Veterinarians have a huge responsibility. A large Veterinarians have a huge responsibility. A large commitment of time and energy will be required commitment of time and energy will be required of us if eradication measures are to be effective.of us if eradication measures are to be effective.

AMVEC is an excellent AMVEC is an excellent Conference Conference

thank you for this opportunity to thank you for this opportunity to attend and to present this paper attend and to present this paper

to you, my colleaguesto you, my colleagues

and for the wonderful hospitality and for the wonderful hospitality in beautiful Puerto Vallartain beautiful Puerto Vallarta

prrs y aujezky

Health & Medicine

movement of virus

animal movement

prv potential vectors

costly diseases of swine

reason virus

equipment caretaker

aujeskys infections

farms control