Malaria Relapse

You can catch malaria when bitten by a female Anopheles mosquito infected with one of four species of the protozoan Plasmodium:

• Plasmodium falciparum is the only species that causes malignant malaria. It causes severe symptoms and is responsible for most fatalities associated with malaria.
• Plasmodium vivax causes benign malaria with less severe symptoms than P. falciparum. However, P. vivax can persist in the liver for years and can lead to a relapse.
• Plasmodium ovale also causes benign malaria and can persist in the blood and liver for many years without causing symptoms.
• Plasmodium malariae causes benign malaria and is relatively rare.

Last week, I had a relapse and felt the same symptoms of malaria, but they went away after only one round of chills, fever and sweating. Based on the low intensity of the symptoms during the acute phase in December and this relapsing episode, I believe I was infected with either P. vivax or P. ovale and I probably have latent hypnozoites in my liver. Primaquine is recommended in this case since it is the only drug currently available that can kill hypnozoites, but it is not available in Liberia. Damn it!!

Figure by Robert Ménard, 2005: Knockout malaria vaccine? (Nature 433, 113-114).