Abstract
Case Report
Kikuyu colobus monkeys (Colobus guereza) at the Los Angeles Zoo have a long history of parasite-associated gastrointestinal problems and poor health. Chronic trichuriasis was present in the group and was documented on many fecals, even though eggs are shed in small numbers and at irregular intervals. One animal died of hemorrhagic gastroenteritis, and two other animals had similar lesions in gastric biopsies. Clinically, these animals had chronic weight loss, inappetance, vomiting, and regurgitation. Trichuris sp. worms were seen in the complex stomach on gastroscopy.
Colobus monkeys are folivorous with an enlarged sacculated stomach which houses a multitude of microbes, very similar to the structure and function of a rumen. The normal pH in the sacculated stomach ranges from 5.5–7, an environment that is fairly similar to the cecum and colon.1,4 Both gastric amebiasis and gastric trichuriasis have been documented in the howler monkey.2 Concurrent infection may add to the pathogenicity of the individual organisms.
Numerous treatments were attempted while the group was on exhibit in an effort to reduce the parasite load. There were many challenges with medication administration and patient compliance. In addition, the exhibit was dirt-floored and heavily contaminated. Trichuris eggs can survive in the environment for up to 5 yr3 resulting in continual reinfection.
Due to the impending acquisition of a breeding male, it was decided to try and resolve the trichuriasis infection. The colobus monkeys were moved to a cement-floored enclosure at the Health Center for a period of 6 mo. During that time, the monkeys were treated with ivermectin monthly at 0.2 mg/kg for three treatments by subcutaneous or intramuscular injection (Ivomec 1% solution, Merial, Iselin, NJ) , fenbendazole at 50 mg/kg PO for 3 days once (Panacur granules 22.2%, Intervet, Millsboro, DE) and milbemycin oxime 5.75 mg PO monthly for 3 mo (Interceptor, Novartis, Greensboro, NC). Attempts at oral administration of albendazole (Valbazen, Pfizer, Exton, PA) were unsuccessful. The treatment choices were based on efficacy and patient compliance. Some of the courses of oral medication were incomplete due to compliance problems. Concurrently, 6 inches of dirt was removed from the floor of the exhibit and replaced.
Multiple negative fecals were obtained prior to the monkeys being returned to their exhibit in December 2001. The group has remained parasite free to date (2004).
Literature Cited
1. Kay, R.N., A.G. Davies. Digestive physiology. In: Davies, A.G., J.F. Oates, eds. Colobine Monkeys: Their Ecology, Behavior and Evolution. New York: Cambridge University Press, 1994.
2. Loomis, M.R., J.O. Britt, A.P. Gendron, H.J. Holshuh, E.B. Howard. 1983. Hepatic and gastric amebiasis in black and white colobus monkeys. JAVMA. 183:1188–1191.
3. Sherding, R.G., S.E. Johnson. Diseases of the intestines. In: Birchard, S.J., R.G. Sherding, eds. Saunders Manual of Small Animal Practice. 2nd ed. W.B. Saunders Co. Pp. 796–798.
4. Sutherland-Smith, M., D.L. Janssen, L.J. Lowenstein. 1998. Gastric analysis of colobine primates. In Proceedings. AAZV and AAWV Joint Conference 1998;136–139.