Data base already contained administrative data about all the soldiers present in Djibouti; and in case of illness symptoms in cause with date of onset and rapid antigenic tests results. Fiftyone cases of tonsillitis were declared during 4 days on 646 soldiers (attack rate 08%), with 18 positive streptotests on 25 performed (72%) (Fig. 2) . Epidemic curve had only one peak as if it was one source of contamination. A retrospective cohort study found one meal at risk (RR 012.8, IC95% 0[7.9Á20.6]), prepared by a local food provider.