Data from a 1979 measles epidemic in an urban district of Guinea- Bissau indicate that state of nutrition is not a major determinant of outcome of infection. However, overcrowding increases the risk of early infection and the severity of disease. In instances in which several children have measles simultaneously, the case fatality rate is significantly higher than for isolated cases. This tendency is apparently a result of intensity of exposure; within the same house, secondary cases have a much higher age-specific case fatality rate than index cases. It is suggested that the association between intensive exposure and severity of infection may be due to increase rates of intercurrent infection and/or a greater dose of infection. Since it is not only the malnourished children who die of measles, vaccination may have a greater importance for survival patterns than has previously been assumed.

No abstract

We studied the occurrence of measles in vaccinated children from an urban area of Guinea-Bissau where measles causes high mortality. Vaccinated children who developed measles required more-intense exposure to become infected (they had a higher ratio of secondary cases [infected in the house] to index cases [infected outside the house]), had a lower mortality among secondary cases, and were less infectious (they generated fewer secondary cases than did unvaccinated children with measles). The attack rate among vaccinated children was significantly higher in households in which someone died of measles. Both severity of infection and development of measles in vaccinated children were related to intensity of exposure. Vaccine efficacy was 72%, and 33% of cases occurred among vaccinated children; however, most mothers remained confident that vaccinated children get milder measles. Moreover, there was significantly greater vaccination coverage among younger siblings of vaccinated children who had contracted measles than among other children in the community.