Malaria: prophylaxis and treatment

The learning resources at the bottom of this page provide links to reliable online materials that present current information about both the Plasmodium species responsible for malaria in humans, and the parasite's lifecycle. These are useful as refreshers for learners.

Non-drug based interventions are effective and include bite-prevention strategies such as protective clothing, mosquito nets, vaporised insecticides and insect repellents that are applied to the skin.

Pharmaceutical treatment and prophylaxis of malaria relies on drugs that target the parasite at crucial stages of its lifecycle. Current drugs kill the asexual blood stage (a.k.a. erythrocytic forms, or schizonts) of the parasite in the blood, the primary and latent liver stages, or gametocytes.

The artemisinins (artesunate, artemether, lumefantrine), chloroquine, mefloquine, quinolones (quinine, quinidine), and antibacterial anti-malarials (pyrimethamine, sulfadoxine, doxycycline, clindamycin) all kill plasmodium parasites during the asexual blood stage.

Atovaquone + proguanil provides additional activity against the primary liver stages of P. falciparum.

Primaquine is effective against primary and latent liver stages as well as gametocytes, and it is most commonly used to eradicate the intrahepatic hypnozoites of P. vivax and P. ovale that are responsible for relapsing infections.

Selecting appropriate drug or drug combination for prophylaxis or treatment is based on the susceptibility of the infecting parasite as determined by the geographical area where the infection was acquired. This map from the US Centers for Disease Control and Prevention (CDC) shows an approximation of the parts of the world where malaria transmission occurs.

Drug based prophylaxis (chemoprophylaxis):

Short-term prophylaxis is recommended for residents from non-malarious countries who are travelling into areas where malaria is endemic. Best practice is to commence treatment before travel into a malaria zone, and to continue for a prescribed period of time after leaving the area.

The drugs used include chloroquine, mefloquine, atovaquone+proguanil and doxycycline. These drugs can be used for long-term prophylaxis and the choice of drug depends upon the extent of anti-malarial drug resistance in the destination area. 

Treating Falciparum malaria (caused by Plasmodium falciparum):

All patients with Falciparum malaria should be admitted for hospital treatment, as there is a high risk of rapid deterioration, even once treatment has been initiated.

First-line treatment for uncomplicated Falciparum malaria is combination artemisinin drugs:  Artemether with lumefantrine is the primary option, with artenimol with piperaquine phosphate as an alternative.  Oral quinine or atovaquone + proguanil hydrochloride is suitable if an artemisinin combination is not available. Quinine is highly effective but poorly tolerated if treatment is prolonged, and this is usually prescribed in combination with oral doxycycline.

If the infection becomes severe or complicated, high dependency or intensive care is necessary, patients should be treated using Intravenous artesunate. If artesunate is temporarily unavailable, i.v. quinine can be administered until the artesunate  arrives. If the patient responds to the initial artesunate, they should be switched to a full course of artemisinin combination therapy (oral quinine + doxycycline, or atovaquone + proguanil hydrochloride are suitable alternatives as described above).

Most P. falciparum is resistant to chloroquine, voiding its use. Due to concerns about adverse effects of mefloquine, the drug is used only when no other treatment options are available.

Treating non-falciparum malaria (caused by Plasmodium vivax, P. ovale, P. malariae,  or P. knowlesi, dependent on geographic location):

The first-line options for P. vivax infections are artemisinin combination therapies, or chloroquine. Artemisinin combinations might offer better coverage in some regions due to chloroquine-resistant strains of P. vivax.

Because of its high activity against hypnozoites, primaquine is used for terminal chemoprophylaxis and radical cure of P. vivax and P. ovale infection.