Neuroscience for Kids - Mosquitoes Target Malaria

Mosquitoes Attracted to People with Malaria

September 19, 2005
How do mosquitoes find their way to a meal of blood? Carbon dioxide and lactic acid that we release when we breathe and sweat are two chemicals that attract mosquitoes. Researchers have discovered something else that makes humans more likely to be bitten: malaria!
Malaria is a disease caused by a one-celled parasite called Plasmodium falciparum. This parasite lives part of its life cycle in mosquitoes and another part in humans (or another "host" animal). New studies show that mosquitoes prefer people infected with the transmissible form of malaria than people not infected by malaria or those infected with the nontranmissible form of malaria.
Researchers went to an area of Kenya where malaria is a problem. They set up three tents built around a central chamber. Each tent was connected by pipes to the central chamber. Inside the central chamber were 100 hungry (malaria-free) female mosquitoes (Anopheles gambiae). At sunset, one child (3 to 15 years old) was placed in each tent and the mosquitoes were released. Some of the children were malaria-free, some had the transmissible form of the malaria parasite and some had the nontransmissible form of malaria. The number of mosquitoes that were attracted to each tent was counted after 30 minutes. The researchers also tested the same children two weeks after they were given medicine to treat malaria. (The mosquitoes could not bite a child because a trap stopped the mosquitoes from reaching the child inside the tent.)

Mosquitoes Attracted to Transmissible Malaria
More mosquitoes were attracted to the children with the transmissible form of malaria. Number of mosquitoes caught in traps leading to:
Child with transmissible malaria = 10.2 mosquitoes
Child with nontransmissible malaria = 5.4 mosquitoes
Child not infected by malaria = 5.3 mosquitoes
After the children were given medicine to treat malaria, the numbers of mosquitoes attracted to the different traps were similar.
The researchers do not know why transmissible malaria makes people more attractive to mosquitoes. They suggest that malaria might change a person's breath or body odor to something especially appealing to mosquitoes.

Malaria

What is Malaria?
Malaria is a disease caused by a parasite and transmitted by mosquitoes. Once inside a host animal, the parasites make their way through the bloodstream to the liver. In the liver, the parasites multiply and cause liver cells to burst. This results in the release of more parasites into the host animal's bloodstream. The parasites go on to infect and kill red blood cells. A mosquito that bites an infected person consumes parasites along with the blood meal. The disease is transmitted to another person when this infected mosquito the bites another person.
Symptoms
Shaking chills, fever, sweating, nausea, headache, vomiting, diarrhea. If untreated, malaria may cause brain, liver, spleen and kidney damage, respiratory problems and death.
Treatment
Antimalarial drugs such as chloroquine, quinine sulfate, hydroxychloroquine sulfadoxine/pyrimethamine (Fansidar), mefloquine, atovaquone/proguanil, doxycycline.
Prevention
Insecticides, insect repellents, antibiotics.

Did you know?

It is estimated that 700,000 to 2.7 million people die of malaria each year; 75% of the people who die of malaria are African children.
Sir Ronald Ross (1902), Charles Louis Alphonse Laveran (1907), Julius Wagner-Jauregg (1927) and Paul Hermann Muller (1948) were awarded Nobel prizes for work associated with malaria.
Only female mosquitoes bite. Male mosquitoes eat mainly fruit nectar.
(Source: CDC)

References and more information about malaria:

Lacroix, R., Mukabana, W.R., Gouagna, L.C. and Koella JC. Malaria infection increases attractiveness of humans to mosquitoes. PLoS Biol., 3:1590-1593, 2005.
All photographs of mosquitoes on this page are courtesy of the CDC and Jim Gathany.
Malaria Facts - from the CDC
Malaria - an interactive tutorial
Malaria - from the Journal of the American Medical Association

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