Spirurids & Oxyurids Flashcards
Spirurid and Oxyurid classification
Phylum: Nematoda Order: Spirurida - Physaloptera: felids/canids - Dracunculus insignis: raccoons/minks/felids/canids - Draschia: equids - Habronema: equids - Spirocerca lupi: felid/canid Order: Oxyurida - Oxyuris equi: equids
Spirurida - morphology
- tight spirally coiled tail of male
- most have 2 lateral lips (pseudolabia)
- esophagus divided into anterior muscular and posterior glandular portion
Spirurida distribution
Worldwide
Physaloptera spp
Stomach worm
- common in midwestern US in dogs and cats
- especially animals with outdoor access/history of prey consumption
Physaloptera life cycle
DH: canids and felids (wild carnivorous mammals)
IH: beetles, cockroaches, crickets (L1 hatches –> L2 –> L3 infective)
PH: amphibians, reptiles, mammals (ingests IH first)
- PPP 41-83 days
- larvated eggs in feces –> DH ingests PH or IH with infective L3 –> L3 attach to stomach wall –> L4 stomach –> adults stomach!
What are the diagnostic stages of Physaloptera?
Adult worms, L1 and eggs
Physaloptera pathogenesis
Adults
- attach to mucosa
- feed on blood and mucus
- ulceration
- catarrhal gastritis
- hemorrhage
Physaloptera clinical signs
Asymptomatic GI - chronic vomiting - secondary to gastritis - esophagitis - regurgitation Systemic (uncommon) - anorexia - weight loss - lethargy
Physaloptera diagnosis - adults
Endoscopy, vomitus
- differentiation from ascarids!
- ascarid found in stomach at necropsy (free)
- physaloptera (uncommon), head embedded in mucosa (attached), prominent collar like cephalic alae
Physaloptera diagnosis - eggs
Not usually found on fecal float!!
- fecal sedimentation: SG >1.2, smooth, thick shell, larvated, easy to miss (clear, oval, small)
Physaloptera treatment and control
Effective treatment difficult
- limit opportunities for ingestion of insect intermediate host
- requires repeated courses of anthelmintics to be effective
- removal of nematodes by endoscopy is curative as long as they are all removed
- immature adults are overlooked
- use anthelmintics after endoscopy
What products are approved for Physaloptera?
No products approved! Off label: - fenbendazole - mebendazole - pyrantel pamoate (tx of choice!) - ivermectin Monthly parasite control products with efficacy against intestinal parasites (macrocyclic lactones) - variable efficacy, limits infections and subsequent clinical disease
Dracunculus insignis
Infections are rare
- distributed in North America
- occasionally found in animals that have been around small lakes and bodies of shallow, stagnant water
- cannot be seen with naked eye
Dracunculus insignis - life cycle
DH: raccoons, mink, canids, felid (rare) IH: copepods (water fleas) PH: frogs - PPP: 200 days - L1 released into water, males die! - DH ingests PH or IH with infective L3 (in water) --> L3 goes to thoracic and abdominal muscles --> L3 subq tissues (by 43 days) --> L4 subq tissues --> adult subq tissues - females subq extremities
Dracunculus insignis pathology and clinical signs
- pyogranulomatous inflammation
- chronic nodules or abscesses (large, primary location in limbs/abdomen)
How to tell apart male/female D. insignis
Females are much larger, males are small and usually found dead
Dracunculus insignis - diagnosis
L1 - impression smear from lesion/discharge - complete digestive tract - prominent, long, pointed tail Adults - remove adult females from nodule
Dracunculus insignis - treatment and control
No effective anthelmintic
- surgical removal and treatment of abscess
Draschia and Habronema - hosts
DH: equids
IH: Musca domestica (house flies, not a blood feeder), Stomoxys calcitrans (stable flies, blood feeder)
Draschia and Habronema - distribution
Worldwide
- in US, house fly is most important!
Draschia and Habronema - life cycle
DH: equid (PPP 2 months)
- L1 +/- eggs in feces –> L3 transferred to DH –> DH ingests IH with infective L3 –> L3 to stomach –> L4 in stomach –> adults in stomach –> eggs hatch in GIT
IH: flies (1 week)
- L1 ingested by fly larvae –> LI to infective L3 in fly –> adult fly feeds on DH –> infective L3 migrate to head of fly –> fly feeds on horse (muzzle, eye, lip) –> L3 transferred to DH –> horse licks and ingests infective L3 or ingest fly –> no blood meal!!!
Draschia and Habronema - pathogenesis
Tumor like lesions near margo plicatus
- fibrous nodules filled with pus like material in which the worms live
What is the difference in the location of adult worms of Draschia and Habronema?
Draschia: found in tumors close to margo plicatus
Habronema: in glandular portion
Draschia and Habronema - clinical signs
Adults (usually asymptomatic) - gastritis - perforation - peritonitis Larvae - granulomatous lesions - cutaneous (summer sores) - both Draschia and Habronema
Draschia and Habronema - diagnosis
Eggs - not fecal float! (fragile, hard to float, hard to find) - PCR of feces to differentiate species Larvae - lesions Adults - necropsy
Draschia and Habronema - treatment and control
- ivermectin
- moxidectin
- infection: rare, surgery
Can you tell Draschia and Habronema larvaed eggs in horse feces apart?
No
- after larvated eggs pass in feces, they are ingested by fly larvae where they develop into infective L3
- flies then deposit L3 around lips of horses
- larvae migrate to mouth and then to stomach
Spirocerca lupi are the _____ worm
Esophageal
Spirocerca lupi - hosts
DH: dogs, cats (PPP 4-6 months)
IH: coprophagous beetle
PH: mammals, birds, lizards, toads
Spirocerca lupi - life cycle
Larvated eggs in feces –> DH ingests PH or IH with infective L3 –> L3 penetrates gastric wall –> L3 walls of gastroepiploic and gastric aa –> celiac artery –> thoracic aorta –> L4 –> adults –> adults migrate to CT and are found in nodules in esophageal wall, stomach
IH: ingests L1 in egg –> L1 –> L2 –> L3 (infective)
PH: PH ingests IH with infective L3
Spirocerca lupi distribution
Worldwide
- warmer climates
- tropical, subtropical
Spirocerca lupi - pathogenesis
Larval migration and adults
- aortic aneurysms
- thrombosis
- esophagus (granulomas, sarcomas)
Spirocerca lupi - pathogenesis
Nodules/granulomas
- form around worms in esophagus
Sarcoma
- worms in wall of esophagus
Spirocerca lupi - clinical signs
- esophageal dysphagia
- vomiting
- esophageal neoplasia
- aortic aneurysm or rupture
- thickening of long bones (hypertrophic osteopathy)
- spirocercosis with associated neoplasia
Spirocerca lupi - diagnosis
Eggs - fecal float (NaNO3) - vomitus (thick shelled, larvated) Adults - vomitus, necropsy
Spirocerca lupi - treatment and control
Off label - doramectin - ivermectin - milbemycin oxime Surgery
Oxyuris equi common name
Pinworms
- non bursate!
Oxyuris equi - life cycle
Eggs L1 –> L2 –> L3 in egg (4-5 days) –> cement dries/cracks, eggs fall off or are rubbed off –> L3 in egg (infective) ingested by DH –> L3 hatch in SI, feed on intestinal mucosa –> 3rd molt in mucosal crypt –> L4 in ventral colon –> 4th molt in dorsal colon –> adults in dorsal colon, feed on gut contents –> only female moves to anus!! –> female lays eggs in gelatinous substance, cement under tail
Oxyuris equi IH and PH
Does not exist!!
Oxyuris equi - pathogenesis
Egg laying females
- primary importance in pathology
- travel to rectum
- females extrude thru the host’s anus
- lay eggs on perineum in clumps contained in gelatinous material
- inflammation of cecum, colon
Oxyuris equi - L4 pathogenesis
L4 has large buccal cavity
- attach to intestinal mucosa
- feed by ingesting plugs
- mucosal erosions = little pathology
Oxyuris equi - adult pathogenesis
Free in intestinal lumen
- feed on gut contents
- no pathology
Oxyuris equi - local clinical signs
- perineal irritation
- inflammation
- intense anal and perineal pruritus
- ulceration
- rubbing
- scratching
- broken hairs
- alopecia
- poor hair coat
Oxyuris equi - systemic clinical signs
- restless
- anorexia
Oxyuris equi - diagnosis
Scotch tape method
- operculated (terminal plug)
- ovoid
- yellowish
- thick shelled
- flattened on one side
Oxyuris equi - treatment and control
Some approved anthelmintics
Management
- strict hygiene (wash perineal region every 4 days)
- avoid fecal contamination (food, water, utensils)
