Travelers should be informed that although antimalarials can markedly decrease the risk for developing symptomatic malaria, none of the agents can guarantee complete protection.9 Travelers should be told to seek medical attention immediately if fever develops during or after a visit to an endemic area. They should be warned that malaria is possible as early as 1 week after first exposure and as late as several months or even years (for P. vivax, P. malariae, and P. ovale) after returning from a trip. Symptoms of P. falciparum almost always begin within 2 months of departure from an endemic area, but only 50% of infected individuals with vivax malaria present in the first 2 months upon arrival home.
Finally, travelers should be informed of the main symptoms of malaria. Fever, malaise, headaches, myalgias, arthralgias, chills, and sweats are seen in more than 80% of patients with malaria. The typical cyclic fevers are often not seen in travelers returning to this country. Other symptoms include anorexia, nausea, vomiting, abdominal pain, and diarrhea.