Epizootic of balantidiasis in lowland gorillas.

Acute enteritis characterized by watery diarrhea and lethargy occurred in 4 lowland gorillas (Gorilla gorilla gorilla) during a 5-week period at the Los Angeles Zoo. Numerous trophozoites of Balantidium coli were seen in fresh feces from each gorilla. Potentially pathogenic bacteria were isolated from 1 fecal sample. Results of fecal flotation examinations were negative for eggs of metazoan parasites. The gorillas were treated with antibiotics and metronidazole or paromomycin, or both. The most severely affected gorilla had blood and mucus in its feces, became dehydrated, and required hospitalization for supportive fluid therapy. This gorilla as well as the other gorillas recovered rapidly with treatment. Balantidium coli was not seen in fecal samples after the gorillas' recovery.