Spirurids & Oxyurids

Question 1

Spirurid and Oxyurid classification

Answer 1

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

Question 2

Spirurida - morphology

Answer 2

• tight spirally coiled tail of male
• most have 2 lateral lips (pseudolabia)
• esophagus divided into anterior muscular and posterior glandular portion

Question 3

Spirurida distribution

Answer 3

Worldwide

Question 4

Physaloptera spp

Answer 4

Stomach worm

• common in midwestern US in dogs and cats
• especially animals with outdoor access/history of prey consumption

Question 5

Physaloptera life cycle

Answer 5

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!

Question 6

What are the diagnostic stages of Physaloptera?

Answer 6

Adult worms, L1 and eggs

Question 7

Physaloptera pathogenesis

Answer 7

Adults

• attach to mucosa
• feed on blood and mucus
• ulceration
• catarrhal gastritis
• hemorrhage

Question 8

Physaloptera clinical signs

Answer 8

Asymptomatic
GI
- chronic vomiting
- secondary to gastritis
- esophagitis
- regurgitation
Systemic (uncommon)
- anorexia
- weight loss
- lethargy

Question 9

Physaloptera diagnosis - adults

Answer 9

Endoscopy, vomitus

• differentiation from ascarids!
• ascarid found in stomach at necropsy (free)
• physaloptera (uncommon), head embedded in mucosa (attached), prominent collar like cephalic alae

Question 10

Physaloptera diagnosis - eggs

Answer 10

Not usually found on fecal float!!

- fecal sedimentation: SG >1.2, smooth, thick shell, larvated, easy to miss (clear, oval, small)

Question 11

Physaloptera treatment and control

Answer 11

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

Question 12

What products are approved for Physaloptera?

Answer 12

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

Question 13

Dracunculus insignis

Answer 13

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

Question 14

Dracunculus insignis - life cycle

Answer 14

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

Question 15

Dracunculus insignis pathology and clinical signs

Answer 15

• pyogranulomatous inflammation

- chronic nodules or abscesses (large, primary location in limbs/abdomen)

Question 16

How to tell apart male/female D. insignis

Answer 16

Females are much larger, males are small and usually found dead

Question 17

Dracunculus insignis - diagnosis

Answer 17

L1
- impression smear from lesion/discharge
- complete digestive tract
- prominent, long, pointed tail 
Adults
- remove adult females from nodule

Question 18

Dracunculus insignis - treatment and control

Answer 18

No effective anthelmintic

- surgical removal and treatment of abscess

Question 19

Draschia and Habronema - hosts

Answer 19

DH: equids
IH: Musca domestica (house flies, not a blood feeder), Stomoxys calcitrans (stable flies, blood feeder)

Question 20

Draschia and Habronema - distribution

Answer 20

Worldwide

- in US, house fly is most important!

Question 21

Draschia and Habronema - life cycle

Answer 21

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!!!

Question 22

Draschia and Habronema - pathogenesis

Answer 22

Tumor like lesions near margo plicatus

- fibrous nodules filled with pus like material in which the worms live

Question 23

What is the difference in the location of adult worms of Draschia and Habronema?

Answer 23

Draschia: found in tumors close to margo plicatus
Habronema: in glandular portion

Question 24

Draschia and Habronema - clinical signs

Answer 24

Adults (usually asymptomatic)
- gastritis
- perforation
- peritonitis
Larvae
- granulomatous lesions
- cutaneous (summer sores)
- both Draschia and Habronema

Question 25

Draschia and Habronema - diagnosis

Answer 25

``` Eggs - not fecal float! (fragile, hard to float, hard to find) - PCR of feces to differentiate species Larvae - lesions Adults - necropsy ```

Question 26

Draschia and Habronema - treatment and control

Answer 26

- ivermectin - moxidectin - infection: rare, surgery

Question 27

Can you tell Draschia and Habronema larvaed eggs in horse feces apart?

Answer 27

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

Question 28

Spirocerca lupi are the _____ worm

Answer 28

Esophageal

Question 29

Spirocerca lupi - hosts

Answer 29

DH: dogs, cats (PPP 4-6 months) IH: coprophagous beetle PH: mammals, birds, lizards, toads

Question 30

Spirocerca lupi - life cycle

Answer 30

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

Question 31

Spirocerca lupi distribution

Answer 31

Worldwide - warmer climates - tropical, subtropical

Question 32

Spirocerca lupi - pathogenesis

Answer 32

Larval migration and adults - aortic aneurysms - thrombosis - esophagus (granulomas, sarcomas)

Question 33

Spirocerca lupi - pathogenesis

Answer 33

Nodules/granulomas - form around worms in esophagus Sarcoma - worms in wall of esophagus

Question 34

Spirocerca lupi - clinical signs

Answer 34

- esophageal dysphagia - vomiting - esophageal neoplasia - aortic aneurysm or rupture - thickening of long bones (hypertrophic osteopathy) - spirocercosis with associated neoplasia

Question 35

Spirocerca lupi - diagnosis

Answer 35

``` Eggs - fecal float (NaNO3) - vomitus (thick shelled, larvated) Adults - vomitus, necropsy ```

Question 36

Spirocerca lupi - treatment and control

Answer 36

``` Off label - doramectin - ivermectin - milbemycin oxime Surgery ```

Question 37

Oxyuris equi common name

Answer 37

Pinworms | - non bursate!

Question 38

Oxyuris equi - life cycle

Answer 38

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

Question 39

Oxyuris equi IH and PH

Answer 39

Does not exist!!

Question 40

Oxyuris equi - pathogenesis

Answer 40

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

Question 41

Oxyuris equi - L4 pathogenesis

Answer 41

L4 has large buccal cavity - attach to intestinal mucosa - feed by ingesting plugs - mucosal erosions = little pathology

Question 42

Oxyuris equi - adult pathogenesis

Answer 42

Free in intestinal lumen - feed on gut contents - no pathology

Question 43

Oxyuris equi - local clinical signs

Answer 43

- perineal irritation - inflammation - intense anal and perineal pruritus - ulceration - rubbing - scratching - broken hairs - alopecia - poor hair coat

Question 44

Oxyuris equi - systemic clinical signs

Answer 44

- restless | - anorexia

Question 45

Oxyuris equi - diagnosis

Answer 45

Scotch tape method - operculated (terminal plug) - ovoid - yellowish - thick shelled - flattened on one side

Question 46

Oxyuris equi - treatment and control

Answer 46

Some approved anthelmintics Management - strict hygiene (wash perineal region every 4 days) - avoid fecal contamination (food, water, utensils)