The Transmission Mode of Malaria

The Directors of Health Promotion and Education (DHPE) estimates that there are 200 to 300 million new cases of malaria a year, with 2 to 3 million of those resulting in death. The Center for Disease Control and Prevention (CDC) lists the following areas as high risk for malaria infections: Africa, Asia, Central and South America, Eastern Europe and the South Pacific. Malaria is a worldwide health problem, even in the United States. Each year, United States citizens are diagnosed with malaria infections. The CDC reports that in 2004, 1,324 cases of malaria were reported in the United States and U.S. territories, with four of the cases resulting in death. The majority of the cases were linked to prior travel to high risk epidemic areas.

Anopheles Mosquitos

The most common way a person contracts malaria is from a bite from an Anopheles mosquito which is infected with a malaria parasite. There are four types of malaria parasites; Plasmodium falciparum is the most dangerous one. The World Health Organization (WHO) estimates that Plasmodium falciparum is responsible for almost one million deaths a year in sub-Saharan Africa.
A female Anopheles mosquito becomes infected with the malaria parasite after biting an infected human. Once infected, the malaria parasites reproduce inside the mosquito's body. After infection, the mosquito passes the parasite through its saliva to anyone that it bites.
Once the parasite enters a human after a mosquito bite, it travels to the liver. In the liver, the malaria parasite rapidly reproduces. Upon maturity, the parasites travel through the bloodstream and infect the red blood cells. The parasites continue to reproduce inside a human's red blood cells, until the red blood cells explode, causing the parasites to further spread throughout the human's body and attack more blood cells. Malaria symptoms develop in seven to 21 days after infection. If left untreated, blood supply is disrupted from flowing to vital organs and death results.

Blood Transfusion

Malaria can be transmitted through a blood transfusion where the recipient receives infected blood. Depending on the type of malaria parasite, a donor can remain contagious from one to 50 years. People who are infected with Plasmodium falciparum parasites stay infected for three to four years. A thorough history and screening of blood donors is useful to prevent transmission of malaria through blood transfusions. The time frame of when malaria symptoms appear after infection from a blood transfusion depends on the amount of malaria parasites transmitted through the blood transfusion.

Needles

Sharing needles is one mode of malaria transmission, especially in malaria endemic areas. If a person uses a needle that was previously used on a person infected with the malaria parasite, she risks becoming infected. The time frame of when symptoms of malaria appear after infection form a needle depends on the amount of malaria parasites transmitted into the bloodstream through the needle.

Congenital Malaria

When an infected mother transmits malaria to her unborn child, it is called congenital malaria. This type of malaria is rare because the placenta often protects the baby from becoming infected with the malaria parasite. In some instances though, the placenta becomes infested with numerous malaria parasites and malaria is passed to the unborn child. Infants who contract malaria in utero are born with malaria symptoms present.

Treatment

Malaria is treated with an antimalarial medication that is designed to kill the malaria parasites. The sooner treatment with antimalarial medication is begun, the higher the chance of recovery. In endemic areas, malaria parasites are developing resistance to some antimalarial medications. When resistance develops, new antimalarial medications are needed. This is a problem in poor areas that cannot always afford a variety of antimalarial medications.

Resources

• Roll Back Malaria: World Malaria Report 2005