6.12 - Other Nematodes Flashcards
What group do the following types of worms belong to
- threadworms
- pinworms
- whipworms
- capillarids
Threadworms: Rhabditids
Pinworms: Oxyurids
Whipworms: Enoplids
Capillarids: Enoplids
Generally, Rhabditis are __________ (interaction with host and environment)
free-living
What size are most Rhabditids
some microscopic; very small
What is the most parasitic of the Rhabditids
Strongyloides
Strongyloides generally infect what area of the host
small intestine, deep within the villi
What is the species of Strongyloides in the following animals:
- People, primates, dogs, cats
- Swine
- Ruminants
- Equids
S. stercoralis
S. ransomi
S. papillosus
S. westeri
What is another name for Strongyloides
threadworms
which Strongyloides species produces free-living larvae in feces that can be detected with the Baermann technique
Strongyloides stercoralis
Describe the morphology of Strongyloides
- adults
- eggs
- adults small and thread-like
- eggs thin-shelled, oval and contain L1
Describe the roles of male and female worms for free-living and parasitic life cycles of Strongyloides
Free-living: occurs with males and females (life cycle maintained in the absence of a host)
Parasitic: only females; females undergo parthogenesis to produce fertile eggs that mature to L1
describe the parasitic life cycle of Strongyloides
transmission of L3 larvae can be through penetration, ingestion or transmammary -> if penetration or transmammary there is somatic and tracheal migration but if ingestion there is only mucosal migration -> females undergo parthogenesis to produce fertile eggs -> eggs/L1 shed in feces
what species of worms can cause autoinfection in immunocompromised individuals
Strongyloides stercoralis
what is the relative length of Strongyloides PPP
short
can you develop immunity to Strongyloides
Yes - generally by 6 months
What is the pathogenesis of Strongyloides stercoralis in small animals
generally non-pathogenic but can cause a non-bloody enteritis
what is the pathogenesis of Strongyloides westeri in horses
inflammation, edema, erosions, enteritis in young animals
what is the pathogenesis of Strongyloides ransomi in swine
enteritis, diarrhea, dehydration in neonates
what is another name for Enoplids
Trichurids
what groups of worms fall under the Enoplids/Trichurids
- trichuris (whipworms)
- capillarids
- trichinella
- Giant Kidney Worm
what is characteristic of all Enoplids/Trichurids
they have an elongate esophagus containing specialized cells cause Stichocytes
T/F there are many different hosts for the Enoplids/Trichurids but each species is host-specific
T
Describe the location in the host for the following Enoplids/Trichurids
- Trichuris
- Capillarids
- Trichinella
Trichuris: cecum, colon
Capillarids: intestine, respiratory tract or urinary tract
Trichinella: intestine
Often buried deeply into the epithelium
describe the morphology of the Trichurid/Enoplid:
- adults
- eggs
- larvae
adults: slender and white
eggs: oval, bipolar plugs
larvae (trichinella): coiled within intestine or muscle cells
what is the general life cycle for the Enoplids/Trichurids
- usually oral ingestion of eggs containing mature larvae
- Trichinella releases larvae that become hypobiotic in the intestine or mm and transmit by scavenging
Describe the morphology of Trichuris
- adults
- eggs
Adults: have a slender anterior end and a thickened posterior end; up to 8 cm
Eggs: bipolar plugs that stick out like a football, smooth and oval, single cell
Describe the Trichuris life cycle
Usually oral ingestion of eggs containing infective larvae -> brief mucosal migration in SI -> adults formed in the cecum and colon
What is special about the Trichuris eggs that influences their survival
environment and frost-resistant
what is the pathogenesis of Trichuris
malabsorption and protein loss causes diarrhea; blood-feeding by some adults causes frank red blood in feces
why might you see clinical signs of Trichuris without seeing eggs on a fecal float
Trichuris has a brief mucosal migration in the SI before having adults in the colon and cecum that embed in the mucosa and blood feed before having sex - the PPP is long meaning you get the pathogenesis from these adults before they have sex and produce eggs
what are the general features of the Capillarids
- host-specific, but some hosts may have multiple species in different predilection sites
- some use intermediate hosts
- prominent stichocytes
how are Capillarids morphologically different from Trichuris and what is the significance
Capillarids are thin throughout their entire length which means that they can completely embed and wander around the mucosa
what is the appearance of capillarid eggs
oval and a non-uniform surface and bipolar plugs that are more flush with the edge of the egg like a rugby ball
describe the capillarid life cycle
both direct and indirect (with earthworms) -> eggs released into the urine or feces depending on where the predilection site is
is the PPP of capillarids long or short
long
what is the pathogenesis of capillarids
usually no clinical disease; respiratory infections can cause coughing/wheezing; heavy intestinal infections can rarely cause enteritis, diarrhea, emaciation
describe the capillarid species in birds that can do the following:
- direct life cycle (2)
- earthworm paratenic host (1)
- earthworm intermediate host (1)
- capillaria contorta and capillaris obsignata
- capillaria contorta
- capillaria caudinflata
describe the pathogenesis and clinical signs of Capillaria contorta
- wall of crop becomes thickened
- weakness and unthriftiness
describe the pathogenesis and clinical signs of C. caudinflata and C. obsingnata
edematous intestine, necrosis of mucosa
decreased production parameters, reddish diarrhea, emaciation
what is the life cycle of Diocytophyme renale (Giant Kidney Worm) - direct or indirect
INDIRECT - uses invertebrate IH and fish as PH
what is the appearance of the Giant Kidney Worm
up to 1 cm diameter and 1 m long females; males smaller; usually in the right kidney but can be in the abdominal cavity; bright red
describe the giant kidney worm eggs
bipolar plugs and corrugated appearance
what is the life cycle of the giant kidney worm
eggs are passed in the urine and mature to contain an infective larvae -> mud worms ingest the eggs -> either ingested by a dog at this stage or works up the food chain to fish which get ingested -> leaves the intestinal tract and matures in the kidney -> eggs passed in urine
is the PPP of Diocytophyme renale long or short
long
Describe the morphology of male and female adult Trichinella
females small, slender, and contain developing larvae
males have two small cloacal flaps on the tail
what is the life cycle of Trichinella spiralis
animals ingest larvae within the muscle of prey -> develop to adults -> mate -> females produce larvae -> larvae leave the gut and travel to other tissues
what is the pathogenesis/clinical signs of Trichinella spiralis
- gastroenteritis
- diarrhea
- muscle pain and inflammation
what is the treatment for Trichinella
no treatment!
most pinworms (oxyurids) are host-specific or nonspecific
specific (and direct lifecycle)
what is the pathogenesis of the pinworms
usually non-pathogenic but irritation and pruritis due to oviposition; may see inflammation and ulceration if large amounts
what is the appearance of pinworm adults and eggs
adults: long, slender with a skinny tail
eggs: oval, operulate, asymmetrical
what is the life cycle of pinworms (oxyurids)
oral ingestion of eggs containing mature larvae -> hatch in the intestine -> larvae mature in the large intestine -> females move to the perianal region to lay eggs
