Molecular Epidemiology and Characterization of Helicobacter Species in Captive Wildlife

Helicobacters are widespread, pathogenic bacteria that infect the stomach, intestine, and liver, causing significant morbidity and mortality. The bacteria have developed sophisticated biochemical systems for rapid genetic change that has made them highly successful and harmful to humans and animals in a variety of ways. Infections typically persist for years and result in inflammation, ulcers, and cancer at sites of colonization and also contribute to heart disease, kidney malfunction, and skin disorders through production of circulating toxins and alteration of the immune system.

In wildlife and zoo animals, the prevalence of helicobacter infection appears to be considerable. A recent study identified helicobacters in 13 of 16 zoo animals tested by polymerase chain reaction (PCR) of fecal samples. At the Zoological Society of San Diego, we have identified an additional eight novel Helicobacter species in mammals, birds, and reptiles by PCR. Based on these findings, it is probable that a majority of animal taxa are infected. Reports of infections in wildlife are limited and have been in socially popular animals, like cheetahs, lions, tigers, and dolphins. In many of these cases, infection has led to significant disease. However, hundreds of animal taxa across broad phylogenetic ranges remain to be examined for infection, and little is known about the ecology and pathogenicity of helicobacters in these groups.

We have begun to survey a diverse assemblage of mammals, birds, amphibians, and reptiles to determine the prevalence of helicobacter infection in animals and the disease they produce. Data is correlated to management practices and potential risk factors. This will provide important advances in understanding the biology of helicobacters by identifying host ranges and sources of organisms, defining pathogenic, commensal, and symbiotic relationships between different hosts and bacteria, and establishing risk for emergent disease. This will be the first analysis for helicobacter infection ever done in animals on a broad-scale. The study will provide valuable data concerning the pathogenicity of Helicobacter spp. in captive settings, will generate hypotheses relevant to the health and management of wildlife, and will develop an initial estimate of the risk for inter-species transmission of helicobacters (including transmission to humans), and emergence of new strains. The project will also be a template for much needed investigations of other significant, widespread pathogens in captive and wild animals and is an important step in addressing and obviating future disease epidemics and minimizing animal suffering from preventable disease.