Parasitology - Lecture 11 (Hookworms) Flashcards
Discuss the basics for hookworms
- Adults live on the small intestine
Ancylostoma species:
- **A. caninum ** –> dogs in southern US
- A. Brasiliense –> dogs and cats in sotuhern US
- A. tubaeforme –> rar in cats
- **Uncinaria stenocephala - ** the northern hookwrm infects dog in northern US
Hook worm mugshots –> discuss the differences in ancylostoma vs uncinaria
- Ancylostoma species –> have teeth; all the better to suck blood
- Uncinaria species –> has cutting plates; does not suck blod as well; Cold resistant eggs
Discuss Hookworms –> lifecycle in dogs
- Adults mate and produce eggs that are released into the enivonrment
- L1 hatches out of the egg to L3 [in envornment]
- Dog eats L3 or L3 penetrates skin or ingetsts paratenics hosts
- Most L3 loarvae goes on a migratory route
- some take the somatic mifration route and become encysted in tissues [somatic and tracheal routes occur in the host animal]
- some take tracheal route to intestine
- in the intestine, some nebcyst in the intestinal mucosa
- some molt to L4, then L5 and then to adult to produce eggs
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Discuss the hookworm lifecycle in dogs in relatiuon to the diagram
After ingestion or skin pentration, many L3 encyst in tissues
PPP 2 weeks
**Transmammary transmisssion ** is common and important
Trancsplacental transmission does NOT occur (unlike ascarids)
Discuss encysted larva in dogs
Encysted larva literally a “bank” of worms
ACtivation of encysted larva: 1) as adult worms are removed from the intestine > encysted larvae are activated > mateture to aduklts to replenish the population
- Larval weak
2) Lactation: larvae head straight for the milk resulting in transmammary transmision
Discuss the hookworm lifecycle in cats
- Adults mate to produce eggs and eggs are released into th eenivonrment
- L1 hatches out of the egg and dvelops to L3 [occurs in the environment]
- Cat eats L3 or L3 penetrates skin or ingests paratenmic hosts
- Most L3 larvcae goes ona tracheal migratory route [occurs in the host animal]
- take **tracheal route ** throuygh lungs to intestine
- Molt to L4, then L5 and then to adulkt to produce eggs
- NNO LARVAL BANKS IN CATS
Discuss the options for transmission for hookwormns in dogs and cats (infection routes)`
- Options for infection:
- 1) ingestion of L3
- 2) Pentration of skin by L3
- 3) Ingestion of paratenic hosts
- ## 4) Transmammary transmission occurs in dogs, and onky occurs during acute infection in cats
Discuss the damage to host when considering hookworms
- worms attach to the mucosa, inject anticoagulants, and suck blood
- worms may detach and move to new sites
- ulcers form where the worm has been feeding
- in severe cases, intestinal hemoorhage may occur
discuss the pathologic effects of hookworm infection
- Damage to host is due to blood lo ss from adult hookworm - anemia
Discuss ‘severe disease’ in relation to hookworms
- Virulence –> ANcylostoma caninum is the most voracious blooduscker
- High number of parasites come from: 1) poorly managed kennels with many untreated animals shedding 2) favorabl environmental conditions (warm and damp)
- Poor nutriton and stress:
- ummmmunological resistance drops
- animal cant compensate for blood loss
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Discuss asymptomatic infections in relation to hookworms
- Species –> Uncinaria in an inefficient bloodsucer
- Age and immune status: older animals are more resistant to infection
- Good health allows for copensation of blood loss
Discuss the different clinical syndromes when considering hookworms
1) Peracute
2) Acute
3) chronic compensated
4) chronic decompensated
Discuss the peracute clinical syndrome
Peracute –> caused by transmammary transmission to neonatal pups
Appear healthy in week 1 bvut by week 2, rapidly detoriate
- anemia and bloody diahhrea
- Disease precedes egg production –> diagnosis is presumptive
- Treat immediately if suspected –> prgnosis is poor
- Bloodtransfusions and supportive therapy
- Immediate anthelmintic
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Discuss the acute clinical syndrome
- Acute –> caused by sudden exposure to large number of enviornmental L3
- Anemia
- Diahhrea with blood
- Clinical disease precedes egg sheddingf by about a week
Prognisi is good with prompt treatment
Discuss chronic compensated clinical syndrome
Chronic compensated –> adult dogs with no clinical signs
- eggs present in efces on routine fecal examinations
- May have slightly low RBC or hemoglobin
Treatment (cure) is challenging –> encysted larva in the larval bank are not affected by routine anthelmintic therapies
Current anthelmintic drugs do not kill wncysted larvae
Discuss teh diagnosis of hookworms
- May be presumtpive in young or acutely infected animals since clnical signs precede the prepatent preiod
- anemia +/- bloody diahhrea
Fecal float –> typically ‘strongygle’ eggs
