[Intervention in a measles outbreak].

BACKGROUND: The description of a community measles epidemic and the activities developed to control the same is presented. Vaccination efficacy was studied by a cases and controls study. METHODS: The study period of the epidemic was from August 1994 to March 1995 and the intervention was performed from January to March 1995. The activities were developed in two phases: the first directed at a descriptive study and control of the outbreak and in the second phase a cases and controls study was designed to evaluate vaccination efficacy (VE%) versus measles. RESULTS: A total of 325 cases of measles were registered over a period of 29 weeks. The greatest attack rate was found in the age group of 5 to 9 years with 5-91 cases/100. The surveillance system and the priorization of activities protocol designed for control of the outbreak were found to be useful. The result of the cases and controls study demonstrated VE% to be 93.5% (84.3-97.3%). CONCLUSIONS: Rapid intervention in the outbreaks of measles is considered fundamental to avoid propagation of the same among the susceptible population. The surveillance system versus the disease should therefore be optimized. Although vaccination efficacy was found to be good, the high rates of attack found in the theoretically vaccinated groups lead to the recommendation of the introduction of a second dosis of the vaccine and to vaccinate the existing non vaccinated sets.