Pertussis: a worldwide problem.

Pertussis is a serious disease for children in all countries, but it is more severe in the developing world. Disease incidence, complication rates and case fatality rates are highest in infants: unimmunized and incompletely immunized young children are also at risk in adults, pertussis is usually mild or asymptomatic, but older individuals may serve as reservoirs for transmission. Some 70 million cases of pertussis were prevented in 1994 due to immunization with the current whole cell vaccine. WHO emphasizes the importance of early completion of the primary series of vaccinations, with three doses of diphtheria-tetanus-pertussis (DTP) vaccine one month apart starting at six weeks of age. For the past five years, nearly 80% of infants worldwide have received three DTP doses by their first birthday. Despite this, an estimated 40 million cases of pertussis occurred in 1994, indicating the need to increase coverage. The challenge is to reach 90% coverage of infants in all countries by the year 2000 but this will require further efforts to improve immunization programmes.