Almost all malaria infections in tropical and subtropical areas are acquired through the bite of female Anopheles mosquitoes, which characteristically feed between dusk and dawn. Malaria can also be transmitted congenitally, as well as through blood transfusions and by contaminated needles. Rarely, the disease is contracted by persons who have never left the developed world. In these instances, malaria is acquired through the bite of infected Anopheles mosquitoes that were accidentally imported or the bite of domestic Anopheles species that have fed on an infected person. Clinical Presentation Rapid diagnosis of malaria requires suspicion of its presence.
Fever is the key clinical finding.
Other manifestations can be protean, and the disease may mimic influenza or gastroenteritis. Leukopenia, thrombocytopenia and anemia may be noted. Most patients develop symptoms within six weeks after they return from a malarious area. In some patients, however, symptoms may not manifest until two to three years after the infection is acquired. Diagnosis Malaria is diagnosed by the demonstration of Plasmodium organisms on specially prepared blood films.