There are now more than 300 million cases of malaria annually, and more than 1.5 million people die of this disease every year. Approximately 230 Americans are diagnosed each year with malaria that they have acquired abroad. Malaria occurs in large areas of Central and South America, sub-Saharan Africa, the Indian subcontinent, Southeast Asia, the Middle East, and Oceania. The risk of getting malaria increases as a traveler spends more time outdoors at low altitudes, especially in the evening in rural areas. Information on malaria risks in various countries changes frequently and is dependent day to day on local conditions.
Malaria is caused by a parasite that is transmitted by mosquitoes.
Anopheles mosquitoes bite during the evening and at night, from dusk to dawn. Malaria is also transmitted from person to person, and cases have been reported from blood transfusions or congenitally from mother to child. Because malaria is caused by a parasite that lives in red blood cells, blood banks put restrictions on blood donations from travelers. Many blood centers defer donors for as long as 3 years if they have taken antimalarial drugs and have visited a malarious area, or for 6 months if they have visited a malarious area without taking antimalarial drugs. Well on the Road - A Practical Guide for the International Traveler, 2001.