Malaria prevention

Which drugs are used for malaria chemoprophylaxis?

A number of antimalarial drugs and their combinations are used for individual and public malaria chemoprophylaxis.

• Mefloquine — is the drug of choice (standard) for the individual prophylaxis of non-immune individuals.
• Doxycycline — a reserve (alternative) drug.
• Savarine — a combination of proguanil and chloroquine.
• Primaquine — used for public chemoprophylaxis (gametocidal agent) and relapse prevention.
• Pyrimethamine — used for public chemoprophylaxis.

Combinations are also used: atovaquone with proguanil or doxycycline, chloroquine with proguanil or primaquine.

In which regions is resistance of the malaria parasite to chloroquine observed?

Resistance to chloroquine is indicated in the sources for Plasmodium falciparum (the causative agent of falciparum malaria): it has developed in most endemic regions. It is also noted that Delagil/chloroquine is currently ineffective for the prophylaxis of falciparum malaria due to the high resistance of Pl. falciparum to the drug.

When can malaria debut after returning from an endemic focus?

The onset of malaria after returning from an endemic focus depends on the duration of the incubation period, which varies among different species of plasmodia. With massive infection, the incubation period can be shortened to a few days. A short incubation period typically ranges from 12 to 17 days, and for malariae malaria — from 3 to 6 weeks. In cases of prolonged incubation (e.g., in Plasmodium vivax and Plasmodium ovale infection), the disease may debut up to 8–12 months or more later.

Which species of malaria parasites are pathogenic to humans?

Four malaria pathogens are indicated in the sources for humans:

• Plasmodium falciparum — causes falciparum malaria (malignant tertian malaria).
• Plasmodium vivax — causes vivax malaria (benign tertian malaria).
• Plasmodium ovale — causes ovale malaria (ovale malaria).
• Plasmodium malariae — causes malariae malaria.

What is the mechanism of action of chloroquine on the malaria parasite?

The mechanism of action of chloroquine on the malaria parasite involves disrupting the parasite's heme metabolism. The drug penetrates the parasite's digestive vacuole and, due to the "ion trapping" effect, becomes ionized in the acidic environment, losing its ability to exit across the membrane and accumulating in high concentrations. Chloroquine binds to ferriprotoporphyrin (an intermediate product of hemoglobin digestion) and blocks its polymerization. As a result, the accumulation of these toxic products causes the death of the parasite.

What methods of nonspecific protection against malaria infection exist?

Nonspecific protection against malaria infection aims to prevent mosquito bites and control vectors. Individual infection prevention includes:

• using repellents;
• installing protective screens on windows and doors;
• using bed nets;
• wearing clothing that maximally covers the arms and legs (outdoors during evening and night hours).

Public prevention measures include mosquito eradication (vector control).

Which drugs are used for malaria prophylaxis in areas with high chloroquine resistance?

When there is a risk of infection with strains of Plasmodium falciparum resistant to chloroquine, mefloquine is indicated in sources for individual chemoprophylaxis. It is designated as the drug of choice due to the high resistance of P. falciparum to chloroquine. Reserve/alternative drugs for chemoprophylaxis are selected by an infectious disease specialist, taking into account the epidemiological situation in the region and individual patient factors; sources list doxycycline, chloroquine + proguanil, atovaquone + proguanil, primaquine, etc.