Malaria in seafarers. 1. The magniture of the problem and the strategy of its control.

Malaria infections among seafarers have been regularly reported from Denmark, Germany, France, Belgium, Italy, Poland, The Netherlands, United Kingdom and other countries. No statistics are available on malaria infections among crews of ships flying "flags of convenience". The estimated number of malaria cases in international seafarers may be between 500 and 1000 each year; and fatalities among them are reported. This has been an important health problem for seafarers and preventive interventions are essential. In the strategy of malaria prevention in this occupational group the most important objective is to prevent death caused by severe Plasmodium falciparum infections, in which the clinical manifestations occurred during the ship's voyage, and the diagnosis and treatment were delayed. Protective measures against malaria on ships, benefits, risks and limitations of chemoprophylaxis are discussed.