Exotic Animal Parasites

Exotic Animal Parasites Dr. D.G. Baker VMED 5235 Fall 2004 Reptile and Amphibian Parasites Protozoa Cryptosporidium serpentis Hypertrophic gastritis in snakes Post-prandial regurgitation w/in 3 days Direct transmission. Cysts passed in feces Cryptosporidium serpentis The stomach is thickened (easily palpated), causing the body to “bulge” Cryptosporidium sp. Gastric mucosal edema & thickening, petechiae, and focal necrosis Demonstrate the small oocysts (2.6 - 6 µ) in PAS, Giemsa, or acid-fast stained fecal smears No treatment Entamoeba invadens Highly pathogenic amoeba in lizards and snakes (most important amoeba of reptiles) Transmission is direct. Cysts passed in feces Terminal phase of infection: lethargy, anorexia, weight loss, vomiting, dehydration, diarrhea, blood and/or mucus in the feces +/- death Swollen liver. Multifocal necrosis and hemorrhagic, necrotizing gastroenteritis Entamoeba invadens Trophozoites= 16 µ Cysts= 11-20 µ and contain 1 - 4 nuclei Stain with PAS Entamoeba invadens Isolate and decontaminate cages w/ 3% bleach. Elevate enclosure temp > 33 C, Rx w/ metronidazole (250 mg/kg q 2 weeks). Treat opportunists with antibiotics Helminths Tachygonetria sp. Pinworms of reptiles, eg turtles, tortoises, and lizards Transmission: direct Adults in the colon Nonpathogenic Tachygonetria sp. Unembryonated eggs in feces Treat with Fenbendazole (100 mg/kg q 2-3 weeks) Pseudocapillaroides xenopi Ulcerative dermatitis in frogs Gray, rough, dry skin that desquamates. Also anorexia, weight loss, and death. May be complicated by secondary bacterial infections, e.g. Aeromonas hydrophila Pseudocapillaroides xenopi Granulocyte infiltration, dermal edema, and widespread separation of the epidermis from the subepithelial spaces Worms are found in the mucus layer overlying the epidermis, and in intraepithelial tunnels. Eggs are embryonated, with bipolar plugs. Pseudocapillaroides xenopi Thiabendazole (0.1 g/L) in the tank water for 24 hours. Repeat in 2 weeks. Alternatively, Ivermectin 20 µg/100 g BW PO. Trematodes Gastrointestinal or pulmonary system parasites of reptiles. Larval forms may be found in host muscle, bile duct, skin, etc. Can cause listlessness, anorexia, weight loss, dyspnea, uremia, pressure necrosis, and death. Pulmonary infections may be worsened by secondary bacterial infection. Trematodes Eggs in feces or in bronchial washings Praziquantel (8 mg/kg IM or PO, repeated in 2 weeks) Cestodes Reptiles (not crocodilians) serve as definitive hosts of cyclophyllidean tapeworms, following the ingestion of intermediate hosts. Reptiles serve as intermediate hosts for pseudophyllidean tapeworms (plerocercoids) if they ingest procercoid-infected copepods; and as definitive hosts if they ingest infected amphibia, fish, birds, mammals, or other reptiles. Cestodes Cyclophyllidean: Finding typical eggs (containing hexacanth embryo) in the feces Pseudophyllidean Coracidium Ligula intestinalis Plerocercoids Cestodes Plerocercoid can migrate through the body of an Intermediate host Cestodes Adult worms: chronic enteritis +/- obstruction Dx (pseudophyllidean): Sparganosis is suspected when SQ or IM lumps are detected (Zoonotic) Dx (cyclophyllidean): Hexacanth eggs in feces Cestodes No effective treatments for migrating larval tapeworms. Spargana can be removed surgically Praziquantel (8 mg/kg PO) can be used to treat adult infections Hookworms Snakes and others- Oswaldocruzia sp. and Kalicephalus sp. (the snake hookworm). Life cycles are poorly known. Infections are direct, and in some cases include larval skin penetration. Oswaldocruzia = intestinal obstruction/peritonitis Kalicephalus = anemia and hemorrhagic ulcers Hookworms The eggs of both genera are similar in appearance and look like typical hookworm eggs, though those of Kalicephalus sp. may be embryonated by the time they pass out in the feces. Hookworms Fenbendazole (100 mg/kg PO repeated in 2 weeks) will likely be effective Oswaldocruzia sp. Kalicephalus sp. Ascarids Ophidascaris sp. and Hexametra sp. are the two most common genera of ascarids found in snakes Inhabit the terminal esophagus, stomach, and/or small intestine Frogs serve as intermediate hosts Ascarids Severe infections can result in gastric impactions, regurgitation, diarrhea, and occasionally bronchopneumonia Lesions include esophagitis and gastritis. Secondary bacterial infections may be followed by systemic disease. Ascarids Thick-shelled ascarid eggs in feces Fenbendazole-100 mg/kg repeated in 2 weeks Arthropods Pentastomes (“Tongue worms”) Porocephalus sp. and Armillifer sp. adults in lungs Kiricephalus sp. and Raillietiella sp. adults in lungs, larvae/nymphs in subcutaneous tissues Kiricephalus sp. adults can also live beneath the scales, communicating with the outside by small breathing holes through which they release eggs. Transmission by ingestion of infected intermediate hosts (e.g. wild rodents/primates) Armillifer armillatus (adult) in snake lung Pentastomes Lethargy, anorexia, dyspnea, subcutaneous nodules (species dependent), and blood-tinged sputum Hemorrhagic, acute inflammatory, or chronic granulomatous reactions in the lungs (pneumonia), or intestinal tract (some species). WBC counts reveal leukocytosis and eosinophilia. Pentastomes Embryonated eggs contain a larva with 2-3 pair of rudimentary clawed legs. Adult pentastomes may exit the nares, mouth, or SQ sites (Kiricephalus sp.). Radiographs may reveal adult worms or calcified cysts. Pentastomes No reliable treatment. Levamisole (5 mg/kg intracoelomically) or benzimidazoles (PO) for adult parasites. Avermectins (+ antihistamines) may be effective against all stages. Surgical removal of nymphs or adults from the lungs or dermis has been reported. Pentastomes NOTE: Ivermectin can be toxic in all reptiles (especially turtles and snakes), should only be given SQ, and can discolor the skin at injection sites Owners should be careful to avoid ingesting pentastome eggs, as humans can serve as intermediate hosts for nymphal stages (Zoonotic) Acariasis (Mites) Ophionyssus natricis, the snake mite, is the most common, and may be a mechanical vector of Aeromonas hydrophila, which causes pneumonia in captive reptiles. Transmission is direct. Eggs are deposited in the environment. The life cycle requires 10-32 days. Acariasis (Mites) Often found under the scales, and between the spectacle and the periocular scales Infested animals rub and twist excessively, seeking relief Severe infestations may cause anemia, debilitation, and death Acariasis (Mites) Brush the snake against a white sheet to check for mites. Mites may also be found in the snake’s water bowl, since infested animals will seek relief there. Acariasis (Mites) Acaricides used to treat other animals may also be effective in eliminating O. natricis Note: Because much of the life cycle of the mite is spent off the host, infestations may be very difficult to eradicate in large snake collections