Malaria in travelers is usually characterized by fever and influenza-like symptoms, including headache and back pain. Vomiting, diarrhea, abdominal cramping, and cough may occur and may be confused with symptoms associated with more common infections. Textbooks often describe the fever as occurring in discrete episodes lasting a few hours every 2 to 3 days; however, in travelers the fever usually has an irregular pattern throughout the day. Disease caused by P. falciparum in travelers most often occurs 9 to 14 days after an infectious bite, but it may occur up to months later, especially in patients who have received suboptimal prophylaxis.
New England Journal of Medicine - Vol. 359, No. 6, August 7, 2008