An unexpectedly high prevalence of colonization with the intestinal spirochaete Brachyspira aalborgi amongst residents of the Indonesian island of Bali

School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia Correspondence David J. Hampson d.hampson{at}murdoch.edu.au Received 25 February 2008 Accepted 1 June 2008 PCR assays designed to amplify DNA from the anaerobic intestinal spirochaete Brachyspira aalborgi were conducted on DNA extracted from 938 faecal samples from 469 residents on the Indonesian island of Bali. The individuals tested were sampled twice in one year and were from four rural villages, one peri-urban centre and the capital city, Denpasar. Overall, an unexpectedly high prevalence of colonization (24.7 %) was found, with prevalence rates at different locations varying from a low of 15.6 % at one village to 41.5 % in the peri-urban centre. Comparison of prevalence rates at the two sampling times suggested that, in many individuals, colonization was likely to be prolonged (>3 months) and/or that reinfection was occurring frequently in these people. Analysis of a questionnaire administered to the individuals who were sampled identified specific risk factors for colonization as location, co-colonization with the related intestinal spirochaete Brachyspira pilosicoli and use of drinking water obtained from wells rather than from taps. No specific associations with clinical symptoms were identified. Abbreviations: CI, confidence interval; OR, odds ratio.