Malaria can relapse due to dormant liver forms (hypnozoites). Which species is classically associated with relapses?

Malaria can relapse due to dormant liver forms (hypnozoites). Which species is classically associated with relapses?

• A. Plasmodium vivax
• B. Plasmodium falciparum
• C. Plasmodium malariae
• D. Plasmodium knowlesi

Answer: (A)

Relapse in malaria comes from dormant liver forms called hypnozoites that can reactivate long after the initial infection, re-seeding parasites into the blood. This hepatic dormancy is most classically seen with Plasmodium vivax. (Plasmodium ovale also has hypnozoites, but vivax is the textbook example.) The other species don’t form hypnozoites: falciparum lacks this hepatic dormancy and relapses aren’t a feature; malariae can persist in the blood and recrudesce, but not from dormant liver forms; knowlesi is a zoonotic malaria with a mainly acute presentation rather than relapse from liver dormancy.

Relapse in malaria comes from dormant liver forms called hypnozoites that can reactivate long after the initial infection, re-seeding parasites into the blood. This hepatic dormancy is most classically seen with Plasmodium vivax. (Plasmodium ovale also has hypnozoites, but vivax is the textbook example.)

The other species don’t form hypnozoites: falciparum lacks this hepatic dormancy and relapses aren’t a feature; malariae can persist in the blood and recrudesce, but not from dormant liver forms; knowlesi is a zoonotic malaria with a mainly acute presentation rather than relapse from liver dormancy.