Malaria is caused by a parasite that is transmitted from one human to another by the bite of infected Anopheles mosquitoes. In humans, the parasites (called sporozoites) migrate to the liver where they mature and release another form, the merozoites. These enter the bloodstream and infect the red blood cells.
The parasites multiply inside the red blood cells, which then rupture within 48 to 72 hours, infecting more red blood cells. The first symptoms usually occur 10 days to 4 weeks after infection, though they can appear as early as 8 days or as long as a year later. Then the symptoms occur in cycles of 48 to 72 hours.
The majority of symptoms are caused by the massive release of merozoites into the bloodstream, the anemia resulting from the destruction of the red blood cells, and the problems caused by large amounts of free hemoglobin released into the circulation after red blood cells rupture.
Malaria can also be transmitted congenitally (from a mother to her unborn baby) and by blood transfusions. Malaria can be carried by mosquitoes in temperate climates, but the parasite disappears over the winter.
The disease is a major health problem in much of the tropics and subtropics. The CDC estimates that there are 300-500 million cases of malaria each year, and more than 1 million people die. It presents a major disease hazard for travelers to warm climates.
In some areas of the world, mosquitoes that carry malaria have developed resistance to insecticides, while the parasites have developed resistance to antibiotics. This has led to difficulty in controlling both the rate of infection and spread of this disease.
Falciparum malaria, one of four different types of malaria, affects a greater proportion of the red blood cells than the other types and is much more serious. It can be fatal within a few hours of the first symptoms.
Symptoms of Malaria
- Muscle pain
- Stools, bloody
Treatment of Malaria
Anti-malarial drugs can be prescribed to people traveling to areas where malaria is prevalent. It is important to see your health care provider well in advance of your departure, because treatment may begin as long as 2 weeks before entering the area, and continue for a month after leaving the area. The types of anti-malarial medications prescribed will depend on the drug-resistance patterns in the areas to be visited.
According to the CDC, travelers going to South America, Africa, the Indian subcontinent, Asia, and the South Pacific should take one of the following drugs: mefloquine, doxycycline, chloroquine, hydroxychloroquine, or Malarone.
Malarone is a relatively new anti-malarial drug in the U.S. and is a combination of atovaquone and proguanil. It may be recommended over the other drugs mentioned, depending on your destination and the possibility of mefloquine resistance.
It is very important to know the countries and areas you will be visiting to obtain appropriate preventive support for malaria.
For active infections
Malaria, especially Falciparum malaria, is a medical emergency requiring hospitalization. Chloroquine is a frequently used anti-malarial medication, but quinidine or quinine, or the combination of pyrimethamine and sulfadoxine, are given for chloroquine-resistant infections.