Yellow Fever: The Global Situation

Article excerpt

Despite the availability of a safe and effective vaccine against yellow fever, the disease has tragically continued to infect and kill thousands of unimmunized people every year. In particular, 1988-90 was an extraordinarily active period for yellow fever, and the global total of 8685 cases and 2643 deaths for these 3 years represents the greatest respective numbers reported to WHO since 1948. The true picture is certainly worse than this, however, since globally each year an estimated 200 000 cases occur, with approximately 30 000 deaths. The disease is endemic only in certain countries in Africa and South America.

In Africa yellow fever periodically explodes out of its endemic cycle to infect large numbers of persons; case fatality rates are high (20-80%) and children are predominantly affected. A total of 33 countries are at risk of the disease in Africa. Over the period 1988-90 the number of cases reported in Africa was 8133, with 2194 deaths. The majority of cases were in Nigeria, but some were also reported from Angola, Cameroon, and Niger.

In contrast to the situation in Africa, in South America yellow fever is predominantly a disease of adult forest workers. All reported cases have occurred in persons infected through contact with the forest cycle. Over the period 1988-90 most of the 552 cases of the disease and 449 deaths were reported from Bolivia and Peru; the remaining cases were reported from Brazil, Colombia, Ecuador, and French Guiana.

Control strategies

Live, attenuated 17D yellow fever vaccine is effective, producing seroconversion rates of 95%. A long history of use of yellow fever vaccine has demonstrated that it is extremely safe, and only 18 cases of encephalitis have been temporally associated with administration of over 200 million doses of the live 17D vaccine strain since 1945. …