DELAYED EXCESS MORTALITY AFTER EXPOSURE TO MEASLES DURING THE FIRST SIX MONTHS OF LIFE

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Abstract
In an urban area of Guinea-Bissau, 71 children exposed to measles before age 6 months had a mortality risk of 34% (95% confidence interval (Cl) 24–47) between 6 and 60 months of age. The mortality risk for the 205 other children of the same birth cohort who had not been exposed to or developed measles was 11% (95% Cl 9–15), a significant difference compared with exposed children. With a version of the Cox regression model, maternal education was found to be the only background factor with a significant effect on mortality. When background factors were controlled for, the mortality of children exposed to measles was significantly higher than that of controls in each of the age intervals 6–11, 12–23, and 24–35 months. For the large subgroup of children of mothers without any formal education, exposed children had 5.7 times (95% Cl 2.7–12.0) higher mortality than did the control children In the age interval 6–35 months. Diarrhea deaths were particularly common among exposed children. Of 22 children who had been exposed before age 6 months during a subsequent epidemic and had a blood test taken, there was a significantly higher mortality risk (27%) between 6 months and 5 years than in the 26 controls who had a blood test (0%). Children who had elevated antibody titers to measles after exposure had a particularly high mortality compared with controls. These results suggest that later childhood mortality may be related to infectious experiences during the first months of life. The possible long-term health consequences of exposure to measles virus should be considered when assessing the value of measles control programs.