Exotic Mammal Parasites

Protozoa

Rabbit Coccidiosis

Rabbits are commonly infected with coccidia

Hepatic= Eimeria stiedae

Intestinal= Many species: most pathogenic are E.intestinalis and E. flavescens

In all cases, the life cycles are direct. Unsporulatedoocysts are released in the bile (E. stiedae) orintestinal contents and exit in the feces.

Sporulation to the infective stage occurs in less than 3days under optimal conditions.

Rabbit Coccidiosis

Mild= asymptomatic. Severe= hepatic (E.

stiedae) or intestinal disease. In all, these may

include severe diarrhea or constipation,

dehydration, anorexia, weight loss, a “pot-belly”,

intussusception, and

death.

Rabbit Coccidiosis

E. stiedae- hepatomegaly with dilated bile ducts

appearing as yellowish granulomatous lesions

throughout the liver. The gallbladder may also be

enlarged and contain exudate.

Intestinal coccidiosis- cecum and colon contain

dark, watery, foul-smelling fluid, with epithelial necrosis,

mucosal ulceration, congestion, edema, hemorrhages,

villous atrophy, and leukocytic exudate.

Rabbit Coccidiosis

E. stiedae- examine bile for oocysts

All species- Histologic or coprologic. Oocystsare difficult to distinguish among Eimeriaspecies.

Rabbit Coccidiosis

Control is centered around adequate cage

sanitation to reduce the likelihood of

overwhelming infection.

Several antiprotozoal agents are effective at

interrupting the life cycles and restoring normal

growth, and can be used during outbreaks.

Amoebiasis

The most pathogenic species of intestinal

amoebae of primates is Entamoeba

histolytica. Old World >New World.

Transmission is via ingestion of cysts.

Trophozoites inhabit the cecum and colon,

and ingest RBCs. Cysts form in the large

intestine and contain up to 4 nuclei when

mature.

Amoebiasis

Usually asymptomatic. However, signs are

more severe in young and/or New World

monkeys, and in all monkeys may include

lethargy, weakness, dehydration, weight loss,

anorexia, vomiting, and diarrhea, which may be

hemorrhagic or catarrhal.

Amoebiasis

Lesions are often flask-shaped, and represent

ulcerative colitis. Some trophozoites may

disseminate and establish abscesses in the

liver, lungs, or CNS. These are often fatal.

Amoebiasis

Trophozoites in wet smears of colonic

material. In fixed preparations, amoebae stain

bright red with PAS; while trichrome, Giemsa, or

iron hematoxylin stains may be used to

demonstrate nuclear morphology. Therefore,

diagnosis is by examination of colonic

contents or feces (stained or wet mount) for

trophozoites or cysts; or histologically for

lesions.

Amoebiasis

Amoebiasis

Amoebiasis

Control is based on strict sanitation, including

elimination of mechanical vectors such as flies

and cockroaches

Cysts are very difficult to kill in the

environment

Amoebiasis

Metronidazole (50 mg/kg PO bid for 10 days)

plus diiodohydroxyquin (30 mg/kg PO sid for

10 days)

NOTE: E. histolytica causes amoebic

dysentery in humans. This can kill you if it

goes to a vital organ and abscesses

Helminths

Trichostrongylosis

Exotic hoofstock are commonly parasitized bytrichostrongyles like those found in domesticlivestock. Transmission is facilitated by overstocking.

Genera most commonly involved includeHaemonchus, Ostertagia, +/- Nematodirus. Whilemild infections are asymptomatic, heavy infections canresult in weight loss, diarrhea, poor body condition,increased susceptibility to other pathogens, andoccasionally, death.

Trichostrongylosis

Control challenges:– 1) getting the curator to correct the high stocking density,

either by removing animals or supplementing feed

– 2) getting anthelmintic into the hoofstock

– 3) avoiding anthelmintic resistance

– Proper assessment comes by doing monthly fecal eggcounts. A few years of this will reveal the natural cycle oftrichostrongyle transmission.

– Strategic treatment plans can then be designed for theparticular situation

Trichostrongylosis

Anthelmintic is best delivered in mineral

blocks, supplemental feed additives, or pour-

ons. Unfortunately, the first two tend to promote

development of resistance, since it is impossible

to accurately dose animals. Handling these

animals is extremely difficult and is dangerous

for both handler and animal.

Lungworm

Opossums (Didelphis virginiana) are commonly

infected with internal parasites, including

Didelphostrongylus hayesi, the opossum

lungworm

Infection requires ingestion of an infective L3 in

a mollusk intermediate host (terrestrial snail).

So is not transmitted in captivity when snails are

excluded.

“Speedbump” the

wild and crazy

‘possum

Speedbump chillin

in his crib

Lungworm

Heavy infections result in signs of severe respiratory

distress, including tachypnea, exercise intolerance,

harsh lung sounds, weight loss, and death

Granulomatous

bronchopneumonia, with worms

identifiable on cut section and

in histologic sectionMale worm

Lungworm

Baermann fecal examination for L1

First stage larva

A bunch of L1’s

Lungworm

Fenbendazole (50 mg/kg PO sid for 14 days)

eliminated infections in 73% of animals treated.

An improvement in efficacy might be realized if

treatment were extended to 21 or 28 days.

Alternatively, a higher dose (100 mg/kg) may

also be more effective though more dangerous.

Rabbit Metacestodiasis

An incidental finding during a rabbit necropsy,

is the presence of metacestode (larval) stages

of tapeworms.

Taenia pisiformis (cysticercus)

T. serialis (coenurus)

Both are transmitted by ingestion of tapeworm

eggs shed by infected dogs

Rabbit Metacestodiasis

The metascestodes develop to the size of a peain the peritoneal cavity attached to the viscera(T. pisiformis) or to a diameter of several inchesin the subcutaneous tissues and intramuscularconnective tissues (T. serialis).

Heavy infections can compromise the health ofthe rabbit, but this is uncommon

Rabbit Metacestodiasis

Diagnose by finding metacestode stages at

necropsy.

Coenurus

Rabbit Metacestodiasis

There is no treatment as antemortem diagnosis

is not done. It is possible that high doses of

praziquantel or albendazole would be curative

Prevent rabbits from grazing on grass

frequented by dogs, and don’t feed rabbit

carcasses to dogs

Arthropods

Sarcoptic Mange

Sarcoptes scabiei: burrowing mite found on >

100 species of mammals, commonly wild canids

and exotic hoofstock (threat to endangered

species)

Each host species has its own strain

Transmission may be direct or indirect

Highly contagious

Sarcoptic Mange

Mites live in tunnels bored in the stratum

corneum

Eggs hatch and develop through larval and

nymphal stages to adults in about 2 weeks

Sarcoptic Mange

Intense pruritus, listlessness, localized (head,

shoulders, backline) or generalized

erythematous eruptions, papule formation,

seborrhoea, and alopecia. Morbidity and

mortality may be high.

Sarcoptic Mange

In chronic cases, skin becomes hyperkeratotic

and lichenified. Pathologic changes are due to

both immediate (type I) and delayed (type IV)

hypersensitivity reactions.

Sarcoptic Mange

Deep skin scrapings (unreliable). To improve

recovery, gently heat scraped material so mites

become active. OR: scrapings can be put in

KOH to digest extraneous material.

Sarcoptic Mange

Eradication is difficult because of environmentalcontamination and infestation of many reservoirspecies

Treatment is with acaricides or avermectins

Treat all animals simultaneously

NOTE: ZOONOTIC

Other Ectoparasites

Exotic livestock andother mammals aresusceptible to infestationwith many of thecommon flies, ticks, andlice of domesticmammals

Treatments are as fordomestics