Nematodes- Order Enoplida & Oxyurida Flashcards
(20 cards)
Superfamily Trichinelloidea: general
- similar esophagus, single column of cells in a tube
- Trichuris: cecum/colon (whipworm)
- Capillaria: alimentary, resp, hepatic, urinary tracts
- Trichinella: small intestine
- mostly DIRECT with L1 infective
Trichuris spp.
Whipworm
-Hosts: dogs, cats (rare in N.america), swine, cattle, ovine, etc
-ID: Adults: shaped like a whip (thick posterior end, thin anterior), head buries into L1, size varies with the host (<2-6 cm), Eggs: lemon shaped w bipolar plugs, size varies, thick and can last in environment
-Per os ONLY
-PPP: ~6 wks (6-12) –> dogs/cats typically seen only after weaning=>10 wks
-Site of infection: cecum/LI (colon)
CS: heavy infections can cause diphtheritic (leathery) inflammation of cecal mucosa & sporadic dz (more common in dogs), can result in d+, wt loss, etc.
-age related immunity
-Dx: double centrifugation (fecal float), important PPP
-Tx: anthelmintics, environmental management (p/u feces), eggs can survive several years
Capillaria spp.
Hosts: dogs, cats, birds (host specific), IH: earthworms (when have indirect life cycle)
-Direct and indirect (depends on spp, infective L1 in egg*
Transmission: per os ONLY
-PPP: species dependent
*Capillaria obsignata: important spp. in birds (pigeons)
-Eucoleus aerophilus: infects airways
-Pearsonema spp: infects bladder
-ID: Adults: thin, hair like, 1-5cm
Eggs: resemble Trichuris but more barrel shaped (more rounded with less obvious bipolar plugs
-Site of infection: Dogs and cats: airways, intestinal tract, bladder
Birds: throughout whole alimentary tract
-Path: Dogs and cats: largely non-pathogenic as incidental finding, asymptomatic
Birds: can be highly pathogenic, varies w spp, necropsy
Dx: varies w species/host
Tx: several anthelmintics, control IH
Trichinella spp.
Hosts: mammals, birds, reptiles
ZOONOSIS
ID: Adults: small intestine, short lived, rarely seen
Larvae: coiled up L1 encysted in striated mm
Transmission: PER OS, must be eaten to continue life cycle–>from raw/undercooked pork and game meats
-L1 infective stage*, can stay encysted for years waiting to be eaten
-Life cycles: Sylvatic (wild), arctic (northern), urban (domesticated): domestic pig cycle= food waste containing infected pig flesh, rats in piggeries, tail biting
-CS: only occur in humans!! detailed hx important, have they been eating raw meat? GI symptoms while in SI, then as larvae spread to mm and experience mm pain
-Dx: pooled sample digestion method, ELISA detects Ab, squash preparation method (no fecal, will never see eggs)
-Tx: pigs not allowed to eat raw meat or carcasses of any animals (including rats)
Superfamily Dioctophymatoidea, Dioctophyme renale
Giant kidney worm Hosts: dogs, foxes, minks IH: earthworm (indirect) PH: frogs or fish (main route) -zoonosis -LARGE nematode, up to 1m -Adults: in kidney, red, start free in abdominal cavity -CS: normally asymptomatic
Order Oxyurida
Pinworms
- Host: species specific
- Common worldwide
- Enterobius vermicularis: in humans
- ID: flatter on one side, large pointed tail
- Life cycle: direct, L3 infective
- CS: pruritus
Superfamily Oxyuroidea, Oxyuris equi
Lg pinworm
Hosts: all equid
Life cycle: direct, infective egg with L3
PPP: 4-5 mo
ID (adults): up to 10 cm long, pointed tail, only females seen
ID (eggs): single operculum, flatter on one side, eggs laid in gelatinous substance (irritant)
ID (larvae): develop into L3 inside egg in environment
Site of infection: dorsal colon/LI, female migrates through anus to lay eggs around perineum
CS: pruritus, peri-anal irritation, broken hair at base of tail, bare patches on hind end
Dx: adhesive tape method, perianal scrapings–> not going to find eggs in species, find in perianal area
Tx: reinfection is common, based on how worms are distributed in the environment –> rubbing annus on things to itch, issue in barns/stables
**remember: pinworms are host species specific! will not infect other species including humans
Order Spirurida
Life cycle: all indirect, L3 infective IH: insects Superfamilies: -Filarioidea -Spriuroidea -Physalopteroidea -Habronematoidea -Dracunculoidea -Thelazioidea
Superfamily Filarioidea
Species: -Dirofilaria immitis -Acanthocheilonema reconditum -Setaria equina -Onchocerca cervicalis Location: NONE in alimentary tract **Females release mff instead of eggs- mff consumed by IH and develop to L3 before infecting FH -PPP: minimum 6 mo
Dirofilaria immitis
Heartworm
Hosts: dogs, cats, other mammals
IH: mosquito
Zoonosis=rare
PPP: 6-9 mo
Site of infection: pulmonary arteries (R heart and cd vena cava in heavy infections)
ID (adults): long, slender, 20-30cm
ID (mff): around 300 um in blood
Path: destroys endothelium from rubbing of worms against artery walls–> lesions, fluid leakage, thrombus formation, tortuous arteries, increased resistance, post-caval syndrome (disrupted valves)
-Wolbachia spp= intracellular bacteria needed for repro and metabolism of heartworm; tx with Doxycycline to start HW tx
CS: determined by pulmonary blood flow and exercise, signalment= >6mo and large outdoor males; asymptomatic, cough, exercise intolerance, etc
Dx: Ag test (need >3 females for positive), SNAP; Knotts/mff tests=need to COMBINE both tests, radiology, ECG
Occult infections: presence of adult worm w/o mff
Tx: prevention is safer than tx**, start preventatives at 3-4 weeks, test before beginning preventative
-MCLs effective against L3 and early L4 (up to 1 mo age)
-eliminate all stages of HW: doxycycline, adulticide, NO EXERCISE, mosquito control
Predilection site: Dogs: distal pulm aa, Cats: lungs
Dirofilaria immitus: life cycle
- female adult releases mff in blood
- mosquito ingests mff, develops to L3
- mosquito bites host transmitting infective L3 larvae
- turns to L4 in a few days, L4 in subQ tissue of thorax/abdomen for 2-3 mo
- L5 moves to bloodstream, then cd pulmonary aa
Dirofilaria immitus: cats
- hard to detect, transient mff, can be in lungs
- potentially fatal
- NO tx for cats
- same sex infections common; if they don’t have any female worms, the Ag test can’t detect infection
Acanthocheilonema reconditum
Hosts: dogs
IH: fleas, lice, ticks
Life cycle: indirect
ID: characteristic mff to distinguish from D. immitis
Site of infection: adults in SQ, mff in blood
CS: considered non-pathogenic, will never know an animal has these, only seen on a blood smear; mff move progressively
“reconditioned” to be less pathogenic than HW
Setaria equina FYI
Host: all equids IH: mosquitoes ID adults: large nematode found in abdominal sx of horses (peritoneal cavity) ID mff in blood CS: considered to be non-pathogenic
“sari surgeon”
Onchocerca cervicalis
Host: all equids
IH: Culicoides spp. (fly)
ID: slender nematodes
Site of infection: Adults coiled in tissue nodules (ligamentum nuchae), Mff in tissue spaces of skin
CS: (from mff): Dermatitis where lesions may be pruritic and often include areas of scale, crust, alopecia, ulceration, etc
Dx: skin biopsy (to detect mff)
Superfamily Spiuroidea, Spirocerca lupi
Esophageal worm
Hosts: dogs, wolves, coyotes, foxes, etc
IH: dung beetles
PH: chickens, birds, lizards
Life cycle: indirect, infective L3
PPP: 6 months
ID adults: pink/red, up to 8 cm long, don’t life freely, create nodules for themselves to live in
ID eggs: small and elongated containing L1, thick shelled, paper clip
Path: large lesions (granulomas) in esophagus from adults, golf ball size. if granulomas don’t have openings into esophageal lumen, eggs will not be laid in ingesta and found in fecal float
Development of complications: osteosarcoma, spondylosis, osteopathies
In FH: migration occurs, L3 penetrates stomach wall and travels vis celiac aa to enter wall of thoracic aorta (adjacent to esophagus)…stays there a few mo then crawls into esophagus and creates nodules
CS: asymptomatic, difficulty swallowing, regurgitation, wt loss
Dx: eggs in feces or vomit (Na nitrate=most sensitive floatation soln); endoscopy and radiography
“loopy ppl who don’t wear their masks can end up with complications from covid in their esophagus…won’t be able to play golf, only able so sit around and play with paperclips
Superfamily Physalopteroidea: Physaloptera spp.
Similar to S. lupi
-Life cycle: indirect, IH insect, L3 infective
-Egg: same
Different than S. lupi:
-CATS and dogs, IH beetles, cockroaches, crickets, PH snakes and birds
-Infective: stomach, differing CS
-PPP: 8-10 wks, (shorter)
-NOT IN NODULES
CS: asymptomatic, vomiting, catarrhal gastritis (inflammation of mucosal membranes of stomach), dark feces (from some blood)
Physically my stomach hurts from feeling inflamed
Superfamily Habronematoidea:
- Draschia megastoma
- Habronema spp.
Stomach nematodes
Hosts: all equids
IH: flies (Musca or Stomoxys calcitrans)
ID adults: 13-25 mm in stomach
ID eggs: thin shelled, larvated, can collapse easily, narrow, weird shape
ID larvae: L3 in skin= wrong place, wrong time
-Flies are attracted to moist areas, can land in wounds, eyes, etc, L3 are deposited and come out but have nowhere to go so they migrate around causing inflammation and severe itching resulting in SUMMER SORES
-Fly larvae in poop with worm eggs, fly larvae eat L1 and molt to next stages together (life cycle synchronized)
Path: Adults: non pathogenic, nodules in stomach. Larvae: cutaneous habronemiasis/draschiasis; granular conjuctivitis (summer sores)
CS: heavy infections –> gastritis, larvae cause summer sores
Seasonality: more summer sores in summer/spring bc of flies
Dx: recovery of eggs in feces is difficult, larvae in scraping skin lesions best
control flies
Habstrakt had a mega concert over the summer, my legs are sore and scraped up
Superfamily Thelazioidea, Thelazia spp.- FYI
Eye worms
Hosts: dogs, equine, bovine, ovine, people
IH: various flies
Infection: conjunctival and lacrimal sacs
Superfamily Dracunculoidea, Dracunculus insignis
Hosts: raccoons, other carnivores, dogs, cats
SQ tissue of carnivores
Guinea worm dz
Creates ulcer- worm must be slowly pulled out of the ulcer
