Incidence, Etiology, and Determinants Associated With Acute Diarrhea Among French Forces Deployed to Chad

Methods. A prospective study was conducted based on physician consultation for diarrhea during a 5-month French forces mandate. Diarrhea was defined as >= 3 loose stools in a 24-hour period or >= 2 loose stools within the last 8 hours. For each diarrheic episode, an anonymous physician-administered questionnaire was completed and a stool sample collected. Samples were tested for parasites, bacteria, and enteric viruses. Global incidence rate was calculated using the mean number of soldiers based in N'Djamena (n = 1,024) over the 5-month period, as denominator. Incidence rates were also estimated for each of the eleven 2-week periods of stay. A case-crossover analysis estimated determinants associated with diarrhea. Results. A total of 240 cases of diarrhea were notified by military physicians, resulting in a global incidence rate of 49 cases per 1,000 person-months (PM). The cumulative individual risk of developing diarrhea during the study period was 0.23. The incidence per 2-week stay began at 8.8/1,000 PM, rose to 54.4/1,000 PM after 1 month, and decreased after 2 months. Of the 240 cases reported, stool samples were obtained for 196 cases. Pathogens were identified in 40% of samples; enteric viruses were predominant (28.1%). Three determinants were associated with diarrhea by multivariate analysis: diarrhea in the close circle [OR: 3.8 (2.0-7.0)]; always eating at the military mess [OR: 0.2 (0.1-0.5)]; or staying in a temporary encampment [OR: 0.3 (0.1-0.8)]. Conclusions. This study found a high frequency of enteric viruses and a high risk of person-to-person transmission associated with diarrhea. Eating at the military mess or staying in a temporary encampment conferred a protective effect. In addition to food-borne disease prevention, stringent hygiene measures are required to break transmission of diarrhea during military deployments.