Shigellosis in Captive Western Lowland Gorillas (Gorilla gorilla gorilla)

A 10-yr retrospective study was performed at the International Wildlife Conservation Park/Bronx Zoo (IWCP) to evaluate the incidence and assess the implications of shigellosis in western lowland gorillas (Gorilla gorilla gorilla). Nine animals had confirmed Shigella flexneri group B isolated from fecal or rectal culture. Bacterial isolates from two individuals were further categorized as subtype 2. Two additional animals that were exposed to S. flexneri-infected gorillas developed diarrhea, but the organism was not isolated from them. Ten of these 11 cases (91%) were infants between 7 and 40 mo of age; one was an 18-yr-old male. Ten of the 11 infants (91%) introduced to the main gorilla colony developed shigellosis. One of the 26 (4%) adult gorillas living at the Great Ape House during the 10-yr period was noted to have shigellosis. The most common clinical presentation was mild to severe diarrhea, lethargy, and anorexia. In all cases, onset of illness in an individual was temporally associated with its introduction to a different gorilla group. Treatment of individual cases varied greatly depending upon the severity of disease, response to therapy, shigella antimicrobial susceptibility pattern, age, and size of the gorilla. All gorillas responded to treatment and recovered. In 1990 S. flexneri isolates from IWCP gorillas demonstrated increased antimicrobial resistance patterns. In 1992, multiple-drug-resistant S. flexneri isolates were also noted in five gorillas at two additional zoological parks that developed shigellosis after arrival of asymptomatic gorillas from the IWCP. DNA fingerprint analysis of the S. flexneri isolates from the IWCP and the other two zoological parks was performed. Plasmid and chromosomal analysis of the S. flexneri isolates suggested that the organism had only been transmitted to one of the zoological parks by an asymptomatic IWCP gorilla. These tests also identified three distinct multidrug-resistant S. flexneri strains from the gorillas; one had originated at the IWCP and the other two were unique to another zoological park.