Introduction

Malaria is one of the most prevalent infectious diseases. Over 40% of the world's population is at risk. There are approximately 300 million cases per year, and over one million deaths, mostly in sub-Saharan Africa and among young children. From the 1940's until the 1970's, malaria incidence decreased. Now, resistance of mosquitoes to insecticides, resistance of malarial parasites to chloroquine and socioeconomic factors are causing reemergence.

The map (left) shows tropical and subtropical nations that have reported endemic malaria to the World Health Organization. Malaria is currently endemic in over 100 tropical and subtropical countries. Although more prevalent in rural areas, malaria is increasing in urban areas.

The majority of malaria patients in the US are travelers, although occasionally travelers infect local mosquitoes and pass the infection to nontravelers. Rarely, people who live near airports are infected by stowaway mosquitoes. The potential for reintroduction of malaria exists anyplace that there are anopheline mosquitoes, including North America.