Direct Transmission

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Direct Transmission
Direct parasite passes directly from one host
to another
Direct
1. Ingests feces/vomit
2. Penetrates skin
3. Transmammary (through the mammary glands)/
transplacental ( through the placenta)
Direct
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Indirect Transmission
Indirect pet ingests a paratenic host
Indirect
Paratenic host an animal that can harbor a
parasite without becoming infected.
Examples rodents, rabbits, birds, flies
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Damage Caused by Ectoparasites
Ectoparasite
1. Damage and irritate skin
2. Cause restlessness, nervousness
3. Transmit infectious organisms
4. Draw blood
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Damage Caused by Endoparasites
Endoparasite
1. Absorb food intended for host
2. Draw blood and lymph fluid
3. Damage tissue and cause internal bleeding
4. Create obstructions in intestines and
circulatory system
5. Produce toxins
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Roundworms
Adults in intestine
Toxocara canis
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Roundworm Lifecycle
3. Larvae are swallowed and mature to adults in
the small intestine.
Toxocara canis Toxocara cati Toxacscaris leonina
4. Eggs are shed in the feces
2. Parasite migrates through various organs to
the lungs and into the trachea
1. Parasite enters host through direct or
indirect (mouse) route
Parasite can be passed to young
Egg embryonates
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Tapeworms
Adult segment in intestine
Dipylidium caninum
Taenia pisiformis
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Tapeworm Lifecycle
Dipylidium caninum
4. Parasite larvae migrate to small intestine
where they mature
5. Proglottids containing eggs are shed in feces
3. Pet eats flea
2. Flea matures
1. Flea larvae eat eggs
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Tapeworm Lifecycle
2. Parasite larvae migrate to small intestine
where they mature
Taenia
1. Dog or cat ingests an intermediate host
3. Proglottids containing eggs are shed in feces
4. Eggs are ingested by an intermediate host
(mouse, rabbit, rats)
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Hookworms
Ancylostoma caninum
Ancylostoma head
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Hookworm Lifecycle
3. Larvae are coughed up and swallowed, ending up
in the small intestine
Ancylostoma caninum
4. Larvae mature, begin to feed, and shed eggs in
feces
2. Larvae migrate to lungs and into trachea
Transplacental or transmammary
1. Larvae are passed to the host through direct
or indirect means
5. Eggs develop into larvae
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Whipworms
Capillaria
Trichuris vulpis
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Whipworm Lifecycle
2. Larvae hatch and begin development in the
intestines
Trichuris vulpis
3. Larvae mature to adults in the cecum or large
intestine
1. Eggs are eaten by host
4. Eggs are passed in feces
5. Eggs develop infective larvae
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Protozoa
Isospora
Giardia cyst
Giardia troph
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Protozoa Lifecycle
3. During maturation, the eggs divide and develop
into male and female
Giardia
2. Parasites cell wall is digested and it enters
epithelial cells of the intestines where it
matures
4. The fertilized female (oocyst) ruptures out of
the epithelial cell and is passed in the feces
1. Eggs are ingested by direct or indirect routes
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Heartworm Lifecycle
4. Microfilaria mature in the heart 3 months
Dirofilaria immitis
3. Microfilaria (larvae) migrate to right side of
heart 3 months
5. After 6 months, adult worms begin producing
microfilaria that are released into bloodstream.
2. Mosquito passes D. immitis to the next animal
it bites
1. Mosquito bites infected animal picking up D.
immitis
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Fleas Ticks
Engorged Ticks
Tick
Flea
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Flea Lifecycle
1. Female flea feeds on hosts blood and lays eggs
Ctenocephalides
2. Eggs fall off host
5. Adult emerges and finds new host
3. Eggs hatch in 2 to 12 days
4. Larvae spins cocoon and pupates for 7days to a
year
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Lice
Trichodectes adult
Nits attached to hair
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Lice Lifecycle
1. Adult lice must live on the host at all times
Mallophaga Anoplura
2. Adult lice lay eggs called nits that stick to
hosts hair
4. Lice are passed to others by direct contact
with an infested host
3. Nit develops into an immature adult stage
(nymph), then into an adult
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Mites
Otodectes
Demodex
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Mite Lifecycle
Demodex burrow into hair follicles other
species burrow into skin or live in ear canals
Demodex canis
Each species of mite has a different lifecycle
Egg
Transmitted to young by direct contact
Nymph
Larva
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Tick Lifecycle
Adults mate and feed on deer
Ixodes dammini
Eggs
Nymphs feed on dogs, other mammals, and humans
Larva
Larvae feed on small mammals
Nymph