Medical ArachnoenthomologyMedical Arachnoenthomology

Plan of lecturePlan of lecture Phylum Arthropoda: general characteristic, Phylum Arthropoda: general characteristic,

classification, medical importance.classification, medical importance. Crustaceans as intermediate hosts of helminthes.Crustaceans as intermediate hosts of helminthes. Class Arachnida: general characteristic, Class Arachnida: general characteristic,

classification, medical importance.classification, medical importance. General characteristics, classification of class General characteristics, classification of class

Insecta.Insecta. Order Anoplura (lice). Morphology, medical Order Anoplura (lice). Morphology, medical

importance, methods of control.importance, methods of control. Order Siphonaptera (fleas). Morphology, medical Order Siphonaptera (fleas). Morphology, medical

importance, methods of control.importance, methods of control. General characteristics, classification, medical General characteristics, classification, medical

importance of order Diptera.importance of order Diptera. Anopheles, Aedes, and Culex mosquitoes and Anopheles, Aedes, and Culex mosquitoes and

their role in transmission of infections.their role in transmission of infections.

Three-fourth of all animal species belong Three-fourth of all animal species belong to the Phylum Arthropoda. The name to the Phylum Arthropoda. The name ““arthropodarthropod” comes from two Greek words, ” comes from two Greek words, arthrosarthros, jointed, and , jointed, and podespodes, feet., feet.

All members of the Phylum Arthropoda All members of the Phylum Arthropoda share the following characteristics: share the following characteristics:

1. Arthropods have jointed appendages. 1. Arthropods have jointed appendages. 2. The arthropod body is segmented. 2. The arthropod body is segmented. 3. Arthropods have an exoskeleton. 3. Arthropods have an exoskeleton. 4. Arthropods have a ventral nervous 4. Arthropods have a ventral nervous

system, an open circulatory system, a system, an open circulatory system, a digestive system, and specialized sensory digestive system, and specialized sensory receptors.receptors.

Phylum Arthropoda includes

3 classes of medical importance:

1.Class Crustacea: cyclops, crabs.

2. Class Arachnida (Octapoda): scorpions, spiders, ticks and mites.

3.Class Insecta (Hexapoda): mosquitoes, flies, bugs, lice, fleas.

Class CrustaceaClass Crustacea Most crustaceans have Most crustaceans have two pairs of antennae,two pairs of antennae, three pairs of chewing three pairs of chewing

appendages, appendages, various numbers of pairs of various numbers of pairs of

legs. legs. Crustaceans differ from the Crustaceans differ from the

insects in that they have legs insects in that they have legs on their abdomen as well as on their abdomen as well as on their thorax. on their thorax.

Medical importance:Medical importance: Cyclopes are intermediate Cyclopes are intermediate hosts of the fish tapeworm hosts of the fish tapeworm (Diphyllobothrium latum) and (Diphyllobothrium latum) and Dracunculus medinensis. Dracunculus medinensis.

Class Arachnida.Class Arachnida. The Class Arachnida is a group of more The Class Arachnida is a group of more

than 100,000 species, including spiders, than 100,000 species, including spiders, scorpions, ticks, and mites.scorpions, ticks, and mites.

Most arachnids are adapted to kill prey with Most arachnids are adapted to kill prey with poison glands, stingers, or fangs. poison glands, stingers, or fangs.

Arachnids have a body that is divided into a Arachnids have a body that is divided into a cephalothorax and an abdomen. cephalothorax and an abdomen.

Attached to the cephalothorax are 4 pairs of Attached to the cephalothorax are 4 pairs of legs, a pair of chelicerae, and a pair of legs, a pair of chelicerae, and a pair of appendages called pedipalps.appendages called pedipalps.

The pedipalps aid in chewing; in some The pedipalps aid in chewing; in some species pedipalps are specialized to species pedipalps are specialized to perform other functions. perform other functions.

Arachnids undergo incomplete metamorphosis.Arachnids undergo incomplete metamorphosis.

Class Arachnida includes 3 orders of medical importance:

Order Scorpiones.

Order Araneae (spiders)

Order Acari (ticks and mites).

5 Interesting Facts 5 Interesting Facts about about ScorpionsScorpions

Scorpions live everywhere but the Scorpions live everywhere but the Arctic and AntarcticArctic and Antarctic

Male and female scorpions find each Male and female scorpions find each other by vibration, scent, or touch. other by vibration, scent, or touch. Then they dance together for half an Then they dance together for half an hour or more.hour or more.

Females often eat the males when Females often eat the males when they are done with the dance.they are done with the dance.

Scorpions have 8 legs and 2 claws.Scorpions have 8 legs and 2 claws.

The bigger the claws are, the less The bigger the claws are, the less venom it has.venom it has.

Diet Small rodents insects

Clawed feetClawed feet

25 types can harm/kill man25 types can harm/kill man

Alive before the dinosaursAlive before the dinosaurs

- Scorpions have greatly enlarged Scorpions have greatly enlarged pedipalps, which they hold in a pedipalps, which they hold in a forward position.forward position.

- They also have a large stinger on They also have a large stinger on the last segment of the abdomen. the last segment of the abdomen.

Pathogenicity.Pathogenicity. The local symptoms The local symptoms of bite include severe pain, of bite include severe pain, inflammation and swelling. inflammation and swelling. Muscular spasm and convulsions Muscular spasm and convulsions can occur in severe cases. Fatal can occur in severe cases. Fatal outcome is caused by respiratory outcome is caused by respiratory failure, pulmonary edema and failure, pulmonary edema and shock. shock.

Control:Control: spraying of insecticides. spraying of insecticides.

Scorpions differ fromScorpions differ from spiders in two ways spiders in two ways::

Spiders are not a “bug”Spiders are not a “bug” Spiders are not insects Spiders are not insects

they are part of a group they are part of a group called Arachnidcalled Arachnid

There are more than There are more than 30,000 different species 30,000 different species of spidersof spiders

ArachnophoArachnophobiabia

Arachnophobia is Arachnophobia is the fear of spidersthe fear of spiders

This is the number This is the number one fear of one fear of Americans todayAmericans today

Although most Although most spiders are spiders are harmless and harmless and helpful to our liveshelpful to our lives

This spider has a venomous bite that causes serious wounds

SpidersSpiders There are about There are about

35,000 named species 35,000 named species of spiders (order of spiders (order Araneae). Araneae).

These animals play a These animals play a major role in all major role in all terrestrial ecosystems.terrestrial ecosystems.

Spiders hunt their prey Spiders hunt their prey or catch it in webs. or catch it in webs.

Spider EyesSpider Eyes

Most spiders have either six or eight eyesMost spiders have either six or eight eyes

Even so they cannot see far awayEven so they cannot see far away

They use the hair on their bodies as They use the hair on their bodies as sensors to feel their way around and to sensors to feel their way around and to tell when other animals are neartell when other animals are near

Order AcariOrder Acari Most mites are small, less than 1 mm long, Most mites are small, less than 1 mm long,

the adult length from 100 nm to 2 cm.the adult length from 100 nm to 2 cm.

the cephalothorax and abdomen are fused into an the cephalothorax and abdomen are fused into an unsegmented ovoid body.unsegmented ovoid body.

Respiration occurs either by means of tracheae or Respiration occurs either by means of tracheae or directly through the exoskeleton.directly through the exoskeleton.

They are found in virtually every terrestrial, They are found in virtually every terrestrial, freshwater, and shallow marine habitat known and freshwater, and shallow marine habitat known and feed on fungi, plants, and animals; they act as feed on fungi, plants, and animals; they act as predators and as internal and external parasites of predators and as internal and external parasites of both invertebrates and vertebrates. both invertebrates and vertebrates.

SarcoptidaeSarcoptidae“Scabies Mites”“Scabies Mites”

Sarcoptes scabieiSarcoptes scabieiAlso called the “itch mite” of Also called the “itch mite” of

humanshumans

Not Vectors of any disease.Not Vectors of any disease. Morphology:Morphology: male (0,2 male (0,2

mm) is smaller than mm) is smaller than female (0,4 mm). female (0,4 mm).

Body is oval, convex Body is oval, convex dorsally and flat ventrally. dorsally and flat ventrally.

Sarcoptes scabieiSarcoptes scabiei (itch mite)(itch mite)

MouthpartsMouthparts::

a)a) rudimentary hypostome rudimentary hypostome without teeth. without teeth.

b)b) chelicerae end in pincer-like chelicerae end in pincer-like structures. structures.

c)c) pedipalps are short and 3-pedipalps are short and 3-segmented. segmented.

The whole cycle takes about 2 The whole cycle takes about 2 weeks.weeks.

DistributionDistribution

WorldwideWorldwide

All races and socioeconomic classesAll races and socioeconomic classes

All climatesAll climates

300 million cases annually!300 million cases annually!

Burrowing initially occurs in thinner skin of Burrowing initially occurs in thinner skin of the body.the body.

Bend of knee and elbow.Bend of knee and elbow. Webbing between fingers and folds of the Webbing between fingers and folds of the

wrist.wrist. Genitalia and buttocks.Genitalia and buttocks. Breasts.Breasts.

Behavior

Scabies RashScabies Rash

Life cycleLife cycle

TransmissionTransmission

Spread by ovigerous female mites through:Spread by ovigerous female mites through:

Personal (prolonged close) contactPersonal (prolonged close) contact Occasionally by infested sheets (rare).Occasionally by infested sheets (rare). Touching or shaking hands (unlikely).Touching or shaking hands (unlikely). Sexual activity.Sexual activity. Among children (outbreaks).Among children (outbreaks). Mites can survive up to 24 hours off host.Mites can survive up to 24 hours off host.

Diagnosis is made byDiagnosis is made by

- itching of affected surfaces itching of affected surfaces at night at night

- specific lesions specific lesions - finding of the parasite in the finding of the parasite in the

tunnels by a needle.tunnels by a needle.

Control is provided byControl is provided by

- proper treatment of infected - proper treatment of infected persons persons

- sterilization of clothes and - sterilization of clothes and beddingbedding

- personal cleanliness.- personal cleanliness.

DiagnosisDiagnosis

TicksTicks

Ticks are blood-feeding ectoparasites Ticks are blood-feeding ectoparasites

(parasites that occur on the surface of their host).(parasites that occur on the surface of their host).

Ticks are divided into hard-bodied ticks (family Ixodidae) Ticks are divided into hard-bodied ticks (family Ixodidae) and soft-bodied ticks (family Argasidae)and soft-bodied ticks (family Argasidae)

TICK LIFE CYCLETICK LIFE CYCLE

- female ticks lay eggs. female ticks lay eggs. - Larvae hatch, feed on Larvae hatch, feed on

blood and then drop to blood and then drop to the ground. the ground.

- Larvae molt into Larvae molt into nymphs. nymphs.

- Nymphs feed on blood Nymphs feed on blood and molt into adults. and molt into adults.

- Adult male and female Adult male and female feed on blood. feed on blood.

- Life cycle takes several Life cycle takes several months (1-2 years in months (1-2 years in some species). some species).

Life cycle:Life cycle:

Anatomy of IXODES ticksAnatomy of IXODES ticks

SizeSize

Female Female Deer TickDeer Tick

Male Deer Tick Male Deer Tick CrawlingCrawling

Female Deer Tick Female Deer Tick LarvaeLarvae

TicksTicks Medical importanceMedical importance.. - Mechanical injury by the bite. - Mechanical injury by the bite. - Tick paralysis: progressive flaccidity due to a failure of acetylcholine - Tick paralysis: progressive flaccidity due to a failure of acetylcholine

liberation in the neuromuscular junction. Tick’s toxin produces a block in liberation in the neuromuscular junction. Tick’s toxin produces a block in the motor nerve fibers. The toxin is elaborated by the tick’s ovaries and is the motor nerve fibers. The toxin is elaborated by the tick’s ovaries and is secreted by salivary glands. secreted by salivary glands.

Vectors of diseasesVectors of diseases: : -hard-bodied ticks (Ixodidae) are carriers of rickettsial, spirochaetal, viral, -hard-bodied ticks (Ixodidae) are carriers of rickettsial, spirochaetal, viral,

bacterial, and protozoan diseases.bacterial, and protozoan diseases. soft-bodied ticks (Ornithodorus) are vectors of endemic relapsing fever soft-bodied ticks (Ornithodorus) are vectors of endemic relapsing fever

(caused by Borrelia duttoni) and Q-fever.(caused by Borrelia duttoni) and Q-fever. Control of ticks:Control of ticks: Repair of cracks. Repair of cracks. Insecticide spraying on floors and cracks. Insecticide spraying on floors and cracks. Infested animals are dusted by insecticide agents or dipped in special Infested animals are dusted by insecticide agents or dipped in special

solution.solution. In endemic areasIn endemic areas:: wear light-colored, tightly woven slacks and a long wear light-colored, tightly woven slacks and a long

sleeved shirt; spray clothing with an insect repellant containing N,N-sleeved shirt; spray clothing with an insect repellant containing N,N-diethyltoluamidediethyltoluamide

InsectsInsects have three body

sections: the head, thorax, and

abdomen; three pairs of legs, all

attached to the thorax; one pair of antennae. they may have one or two

pairs of wings. The mouthparts of insects

are elaborate. There are two principal

kinds of metamorphosis in insects: simple and complete.

InsectsInsects Class Insecta is divided into 4 orders of Class Insecta is divided into 4 orders of

medical importance: medical importance:

1. Order Anoplura (lice). 1. Order Anoplura (lice).

2. Order Siphonaptera (fleas).2. Order Siphonaptera (fleas).

3. Order Hemiptera (bugs).3. Order Hemiptera (bugs).

4. Order Diptera (mosquitoes and flies).4. Order Diptera (mosquitoes and flies).

Order Anoplura Order Anoplura (lice)(lice) Order Anoplura Order Anoplura (lice). Body is flattened (lice). Body is flattened

dorso-ventrally.dorso-ventrally. Lice are wingless insects with short legs.Lice are wingless insects with short legs. Order Anoplura displays incomplete Order Anoplura displays incomplete

metamorphosis. metamorphosis.

Head louseHead louse MorphologyMorphology (Pediculus humanus): (Pediculus humanus): Adult louseAdult louse is 2-5 mm in size, male is is 2-5 mm in size, male is

smaller than female. smaller than female. Body is divided into head, thorax and Body is divided into head, thorax and

abdomen. abdomen.

The head louse found on The head louse found on humans is specific to humans is specific to people. It can’t be people. It can’t be contracted from the contracted from the family dog, cat or any family dog, cat or any other animal. Mammals other animal. Mammals and birds can have lice and birds can have lice but they are species but they are species specific. specific. These are insects that These are insects that

CANNOT jump or fly.CANNOT jump or fly. Their method of Their method of

movement relies on 6 movement relies on 6 legs, each of which ends legs, each of which ends in a claw which can in a claw which can grasp human hair. grasp human hair.

LiceLice Life cycle.Life cycle. - Female louse lays about 10 eggs daily.- Female louse lays about 10 eggs daily. Eggs are cemented to hairs or to fibers of Eggs are cemented to hairs or to fibers of

clothes. clothes. Eggs hatch in about one week. Eggs hatch in about one week. Nymphs feed on blood and pass through 4 Nymphs feed on blood and pass through 4

instars.instars. Adult louse emerges in about two weeks.Adult louse emerges in about two weeks.

Disease transmission (body louse).Disease transmission (body louse). 1.Epidemic typhus caused by Rickettsia 1.Epidemic typhus caused by Rickettsia provaceki, Trench fever. Epidemic provaceki, Trench fever. Epidemic relapsing fever relapsing fever

Transmission of Head LiceTransmission of Head Lice Host-to-host (direct contact from Host-to-host (direct contact from

someone who is infested)someone who is infested)

By wearing infested clothing By wearing infested clothing (hats, scarves, coats, hair (hats, scarves, coats, hair ribbons etc.)ribbons etc.)

By using infested combs, or By using infested combs, or brushesbrushes

By lying on a bed, couch or By lying on a bed, couch or carpet that has carpet that has recently recently been in been in contact with an infested personcontact with an infested person. .

Head Lice are NOT known to transmit Head Lice are NOT known to transmit pathogens (germs). They are a pathogens (germs). They are a nuisancenuisance but NOT a health hazard.but NOT a health hazard.

Lice don’t mount expeditions, striking off Lice don’t mount expeditions, striking off to find new heads. They are obligate to find new heads. They are obligate human parasites, their goal is to stay on human parasites, their goal is to stay on the head where they presently live!!!!!the head where they presently live!!!!!

About 2500 species, most parasites of mammalsonly approx. 100 species on birds

Temporary obligate parasites, blood-feeding exclusively as adults

Most fleas of medical and veterinary importance are not host species-specific

increases the potential for acquisition and transmission of pathogens

Order Siphonaptera (fleas)Order Siphonaptera (fleas)

Flea Life Cycle

Flea eggs

Adult fleas

Important Flea Species

Xenopsylla cheopis (Oriental rat flea) - primary urban plague vector

Pulex irritans (human flea) - occasional epidemic plague vector

Ctenocephalides felis, C. canis, - cat and dog flea - primary pest species

Tunga penetrans – sand flea (chigoe)

Parasitic Flies Parasitic Flies Class HexapodaClass Hexapoda Order DipteraOrder Diptera

Flies - DipteraFlies - Diptera

The key The key distinguishing adult distinguishing adult structure : structure : two two wings. wings.

All Flies are All Flies are HolometabolousHolometabolous (having a complex (having a complex metamorphosis metamorphosis i.e. egg, larvae i.e. egg, larvae

pupa, and adult) pupa, and adult)

One of Great Adaptations of of Flies - One of Great Adaptations of of Flies - The Habitat of larval stageThe Habitat of larval stage

The habitat of the The habitat of the larval stage is larval stage is basically “basically “aquatic or aquatic or semi-aquatic,”semi-aquatic,” and and they have adapted to they have adapted to live in very, very live in very, very “challenging” “challenging” environments.environments.

Allows them to invadeDead and Living tissues

Diptera – Flies as parasitesDiptera – Flies as parasites

EctoparasitesEctoparasites1.1. Adults are free Adults are free

living but blood living but blood feeding with the feeding with the larvae stages larvae stages aquatic or in moist aquatic or in moist semi-aquatic semi-aquatic habitats. habitats. ((Nematocera and Nematocera and BrachyceraBrachycera))

Diptera – Flies as parasitesDiptera – Flies as parasites

2.2. Adults Adults ectoparasites (or ectoparasites (or blood feeding) blood feeding) butbut larvae develop larvae develop within female and within female and essentially pupate essentially pupate after emerging after emerging from mother from mother ((Glossina, Glossina, Hippoboscidae)Hippoboscidae)

Diptera – Flies as parasitesDiptera – Flies as parasites

EndoparasitesEndoparasites 3.3. Adults free living Adults free living

but larvae are but larvae are internal or partially internal or partially internal (flesh internal (flesh feeding) parasites feeding) parasites of vertebrates of vertebrates ((Oestrus, Oestrus, Gasterophilus, Gasterophilus, Cochliomyia Cochliomyia hominovoraxhominovorax)) Gasterophilus intestinalis

Myiasis DefinedMyiasis DefinedThe invasion of organs and tissues of The invasion of organs and tissues of

humans or other vertebrate animals with humans or other vertebrate animals with dipterous larvae, which for at least a dipterous larvae, which for at least a period feed upon the living or dead tissue period feed upon the living or dead tissue or, in the case of intestinal myiasis, on the or, in the case of intestinal myiasis, on the host’s ingested food.host’s ingested food.

Metallic FliesMetallic Flies

Cochliomyia hominivoraxCochliomyia hominivorax

Lucilia spp.Lucilia spp.

Calliphora spp. Calliphora spp.

Musca domestica.Musca domestica.HouseflyHousefly is a medium-sized fly, 6- 10 is a medium-sized fly, 6- 10

mm in length; the female is generally mm in length; the female is generally slightly larger than the male. slightly larger than the male.

Distribution:Distribution: cosmopolitan. cosmopolitan. MorphologyMorphology.. Adult fly has a gray color. Adult fly has a gray color.

Body is divided into head, thorax, and Body is divided into head, thorax, and abdomen.abdomen.

Life cycleLife cycle.. 1. Eggs1. Eggs are laid into masses are laid into masses of decaying organic substances, of decaying organic substances, garbage, refuse or manure.garbage, refuse or manure.

2. Larvae2. Larvae hatch in 6-24 hours and feed hatch in 6-24 hours and feed on organic matter.on organic matter.

3.3. They molt 2 times giving 3 larval They molt 2 times giving 3 larval stages.stages.

4.4. The third larva pupates inside the The third larva pupates inside the larval skin. larval skin.

5. The adult emerges after a few 5. The adult emerges after a few days .The whole cycle takes about one days .The whole cycle takes about one week. week.

House flyHouse fly

4 dark stripes

4th vein angled

Red eyes

Breeding mediaBreeding media GarbageGarbage Decaying fruit or Decaying fruit or

vegetablesvegetables Decaying meatDecaying meat Human or animal fecesHuman or animal feces Grass clippingsGrass clippings

Medical importanceMedical importance1. Indirect mechanical transmission of 1. Indirect mechanical transmission of

microorganisms (as typhoid, poliomyelitis microorganisms (as typhoid, poliomyelitis and bacillary dysentery), eggs of helminthes and bacillary dysentery), eggs of helminthes and cysts of protozoa. and cysts of protozoa.

2. Accidental myasis.2. Accidental myasis.ControlControl

1.1.Sanitary disposal of refuses, garbage and Sanitary disposal of refuses, garbage and manure (breeding media) by dumping, manure (breeding media) by dumping, burning or application of insecticides. burning or application of insecticides.

2.2.Control of adult flies by screening or space Control of adult flies by screening or space spraying of insecticides.spraying of insecticides.

MosquitoesMosquitoes Bloodfeeding - only females Bloodfeeding - only females

take bloodtake blood

Males and females feed on Males and females feed on plant sugarsplant sugars

Gonotrophic cycle - feed, egg Gonotrophic cycle - feed, egg development, oviposition development, oviposition (half-gravid, gravid)(half-gravid, gravid)

Egg biologyEgg biology - oviposition - oviposition location, type of egg, location, type of egg, desiccation resistance, desiccation resistance, diapausediapause

Larval biologyLarval biology - aquatic, - aquatic, spiracle for breathing, filter-spiracle for breathing, filter-feeders, some cannibalistic, feeders, some cannibalistic, variable habitatsvariable habitats

Eggs – 3 strategiesEggs – 3 strategies Singly on water surfaceSingly on water surface

AnophelesAnopheles Singly in a pile, on moist substratesSingly in a pile, on moist substrates

Aedes/OchlerotatusAedes/Ochlerotatus Form of a raft, on water surfaceForm of a raft, on water surface

CulexCulex CulisetaCuliseta

Differences between Anopheles and Differences between Anopheles and Culex.Culex.

Larval Stage – Growth Larval Stage – Growth StageStage

Larval instars (4)Larval instars (4) Aquatic, Filter feedersAquatic, Filter feeders RespirationRespiration

Anopheles

Pupa – Lighter than waterPupa – Lighter than water

Non-feedingNon-feeding RespirationRespiration

Anopheline Culicine

Pupal Stage ComparisonPupal Stage Comparison

Mosquito Pupa and LarvaeMosquito Pupa and Larvae

Mosquito Emerging from Pupal Exuvia

AdultsAdults

Anopheline

Culicine

Adult Stage ComparisonAdult Stage Comparison

EmergenceMatingFeeding

Aedes aegyptiAedes aegypti

Anopheles Culex

Thank you Thank you

for attention !for attention !