A more recent study from Niakhar, a rural area of Senegal, has shown that children treated with prophylactic antibiotics had a lower frequency of respiratory complications. In 1987 it was decided that all children younger than 3 years of age seen within the first 2 weeks of the onset of measles symptoms should be treated with the antibiotic trimethoprim-sulfamethoxazole for 7 days irrespective of whether they had signs of bacterial infection at the time of clinical examinations. Children younger than 3 years of age who had received prophylactic antibiotics were less likely to have respiratory symptoms on days 8 to 15 of illness than children of the same age group who had not received antibiotics because they were seen for the first time on days 8 to 15 (relative risk, 0.37 (0.15 to 0.94)). Further, the case-fatality rates adjusted for age declined 2-fold between 1983-1986 and between 1987-1991 (mortality ratio, 0.41 (0.21 to 0.81)).