QUESTION

If a mosquito carrying malaria is biting you, do you get sick the next day?

ANSWER

No.  There is a delay called the incubation period, which usually is between 7 to 30 days (depending on the malarial parasite the anopheles mosquito is carrying). The shorter periods are observed most frequently  from P. falciparum and the longer ones with P. malariae.

Antimalarial drugs taken for prophylaxis by travelers can delay the appearance of malaria symptoms by weeks or months, long after the traveler has left the malaria-endemic area. (This can happen particularly with P. vivax and P. ovale, both of which can produce dormant liver stage parasites; the liver stages may reactivate and cause disease months after the infective mosquito bite.)

Such long delays between exposure and development of symptoms can result in misdiagnosis or delayed diagnosis because of reduced clinical suspicion by the health-care provider. Returned travelers should always remind their health-care providers of any travel in malaria-risk areas during the past 12 months.