How long do Plasmodium species incubate in humans?

Updated: Apr 26, 2019
  • Author: Thomas E Herchline, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Each Plasmodium species has a specific incubation period. Reviews of travelers returning from endemic areas have reported that P falciparum infection typically develops within one month of exposure, thereby establishing the basis for continuing antimalarial prophylaxis for 4 weeks upon return from an endemic area. This should be emphasized to the patient to enhance posttravel compliance.

Rarely, P falciparum causes initial infection up to a year later. P vivax and P ovale may emerge weeks to months after the initial infection. In addition, P vivax and P ovale have a hypnozoite form, during which the parasite can linger in the liver for months before emerging and inducing recurrence after the initial infection. In addition to treating the organism in infected blood, treating the hypnozoite form with a second agent (primaquine) is critical to prevent relapse from this latent liver stage.

When P vivax and P ovale are transmitted via blood rather than by mosquito, no latent hypnozoite phase occurs and treatment with primaquine is not necessary, as it is the sporozoites that form hypnozoites in infected hepatocytes.


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