Malaria Risks

Human malaria is caused by four species of Plasmodium: Plasmodium falciparum, P.vivax, P.ovale, and P.malariae.

The malaria situation is getting worse in many areas, and prevention and treatment of falciparum malaria are becoming more difficult because the resistance of the P.falciparum to antimalarial drugs is increasing and becoming more widespread. Resistance of P.vivax to chloroquine has been reported from Irian Jaya, Myanmar, Papua New Guinea and Vanuatu. However, poor compliance with prophylactic regimens remains the major reason for malaria in travellers.

In many countries of Asia, the eastern Mediterranean area, and South America where there is malaria, the main urban areas are free of transmission of the disease, although this is not necessarily true of their outskirts or of main urban areas in Africa and India. While there is usually less risk of malaria at altitudes greater than 1500 metres, the disease can occur in favourable climatic conditions at altitudes up to almost 3000 metres. The risk of infection may also vary according to the season, being highest at the end of the rainy season. There may be no risk in many tourist destinations in South-East Asia and Latin America. Travellers to countries where malaria transmission is heterogeneous should be advised of the risk of malaria in the specific zones that they will be visiting. If specific information is not available before travelling, they are recommended to assume uniform high malaria risk throughout the country. This applies particularly to those backpacking to remote places and visiting areas where diagnostic facilities and medical care are not readily available.