Helicobacter pylori infection in rural China: Exposure to domestic animalsduring childhood and adulthood

Little is known about the mode of transmission of Helicobacter pylori, one of the most common human bacterial infections. Some domestic animals, inclu ding the cat, have been suggested as a reservoir of H. pylori disease, but the data have been inconsistent. This paper evaluates the role of exposure to pets and other domestic animals in the etiology of H. pylori in a rural area of China with a high prevalence of H. pylori infection. In this double -blind, population-based, cross-sectional investigation, interviews were co mpleted with 3288 (1994 seropositive, 1019 seronegative, 275 indeterminate) H. pylori-infected adults enrolled in a randomized intervention trial in L inqu County, Shandong Province, China. We found no evidence to suggest that exposure to pets or other domestic animals during either childhood or adul thood was related to the prevalence of H. pylori infection. In fact, odds r atios (ORs) were reduced for subjects who had kept a cat (OR = 0.7, 95% CI 0.4-1.0) or any animal (OR = 0.5, 95% CI = 0.3-0.9) in the house as an adul t, or a cat as a child (OR = 0.7, 95% CI 0.5-1.0). ORs were also reduced fo r all 11 types of animal studied that subjects had kept in their courtyard as an adult. These findings suggest that zoonotic transmission, including t hat from domestic cats, is an unlikely route of H. pylori infection in this rural Chinese population.