Pre-exposure anti-Campylobacter jejuni immunoglobulin A levels associated with reduced risk of Campylobacter diarrhea in adults traveling to Thailand

Diarrhea history questionnaires were administered to 369 U.S. military volu nteers before and after deployment to Thailand. Additionally, blood samples obtained from a subset of 221 volunteers 1-3 weeks previously and 3-4 week s after their deployment were tested by enzyme-linked immunosorbent assay f or immunoglobulin A to Campylobacter jejuni. Stool samples from personnel ( including volunteers) contracting diarrhea in Thailand were cultured for en teric pathogens. Overall, 35.2% (130 of 369) of questionnaire respondents r eported one or more diarrhea episodes during their trip. Volunteers with pr etravel anti-C. jejuni reciprocal titers less than or equal to 450 were 1.6 times as likely to have had diarrhea during their stay in Thailand compare d with those with pretravel titers > 450 (39.7% versus 25.3%; P = 0.05). Th e symptomatic seroconversion, or attributable Campylobacter diarrhea attack rate, for the I-month exercise was 12.7% (28 of 221). The symptomatic sero conversion rate in nonimmune (titer less than or equal to 450) volunteers w as 17.1%, whereas that in immune volunteers was only 4.0% (P = 0.002). Camp ylobacter jejuni or C. coli were recovered from 32.9% (56 of 170) of stool samples cultured and were the most commonly identified enteropathogens. Cam pylobacter diarrhea was associated with elevated temperatures, fecal red ce lls, and fecal white blood cells. The results of this study show that Campy lobacter continues to represent a significant health threat to Western trav elers to Thailand, but many of these travelers have preexisting Campylobact er immunity that protects them from clinically significant Campylobacter en teritis.