Incidence, etiology, and determinants associated with acute diarrhea among French forces deployed to Chad

This study assesses, for the first time, the incidence, etiology, and determinants associated with traveler's diarrhea (TD) among French forces deployed to N'Djamena, Chad.

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.

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)].

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.