The female Anopheles mosquito may well be the most dangerous creature on Earth. When she lands on human skin, she sucks up blood through her needle-shaped mouth and injects saliva into the wound. If this saliva contains Plasmodia parasites, the victims will soon suffer severe fever, violent shivering, and profuse sweating — the telltale symptoms of malaria.
"Malaria" is a misnomer. Drawn from the Italian mala aria, or "bad air," the name reflects the historical belief that the disease is caused by miasmas, or noxious exhalations from rotting matter or stagnant water. In 1889, a tiny parasite was revealed as the disease-causing agent, and eight years later, the mosquito was identified as the parasite-carrying agent.
When a mosquito carrying malaria bites her victim, she injects parasites into the bloodstream, where they migrate to the liver and other organs and incubate. A malaria victim may show no symptoms for weeks or months during this incubation. Then the parasites return to the bloodstream and invade the red blood cells. Rapid multiplication of the parasites ruptures the red cells, releasing more parasites into the bloodstream and causing the characteristic symptoms. If the person does not receive prompt and effective drug therapy, damage may occur to the brain and other organs, sometimes leading to death.
Malaria is largely a geographical disease, endemic to tropical climates in Africa, Asia, and South America. An estimated 350 million to 500 million people worldwide are infected with malaria each year; of the more than one million who die, two-thirds are children. An African child under 5 suffers on average six bouts of the recurring illness each year.
In the United States, malaria was historically a problem in the southeastern states. Begun in 1947, the National Malaria Eradication Program (the precursor of the Centers for Disease Control, or CDC) applied the insecticide DDT to the interior surfaces of rural homes and entire properties where malaria was reportedly prevalent. About 4.6 million houses were sprayed, and five years later, malaria was considered eliminated in the United States.
A remarkable man named Fred Soper first took on malaria in Brazil in the 1930s. With the passion and determination of a field general directing an army, Soper eliminated the Anopheles gambiae mosquito from the country within a decade, stopping a deadly outbreak in its path. His success raised hopes that malaria could be eliminated worldwide. By 1948, 55 nations had signed up for the Global Malaria Eradication Program Soper would go on to lead.
With DDT as their tool, Soper's mosquito warriors were successful in sharply curtailing malaria or eliminating it entirely from nearly 40 countries, including Taiwan, many Caribbean nations, the Balkans, and parts of North Africa. But just as they seemed to be on the brink of victory, their luck ran out. First, mosquitoes began to develop resistance to DDT, and then, in 1962, Rachel Carson's Silent Spring identified the harmful effects of DDT on ecosystems. The chemical was subsequently banned in the United States. While this action benefited the environment, it hurt Soper and his team's international efforts to combat malaria, in which only a small amount of DDT was used indoors. To this day, researchers continue to look for a chemical comparable to DDT in its mosquito-killing effectiveness.
Despite decades of research work, a successful vaccine for malaria remains elusive. Scientists hope that the genetic decoding of the malaria parasite may offer helpful points of intervention for interrupting its life cycle. Meanwhile, several current research efforts seem promising, largely bolstered by the Bill & Melinda Gates Foundation (The Bill & Melinda Gates Foundation is a funder of the Rx for Survival project).
People residing in non-malaria-endemic areas are normally safe in their home countries, although a few cases are reported each year of "airport malaria," in which a mosquito, hitching a ride on an aircraft, causes disease. Travelers to malarial areas have a high risk of catching a serious infection because they lack the natural immunity that provides local residents some protection.
Tourists can take an antimalarial drug as an effective preventative. (If taken for a long time, some of these drugs have long-term side effects, and are therefore not recommended for residents of malaria-endemic regions). Doctors may prescribe a course of medication for travelers that covers the immediate time before, during, and after a visit to a malaria area. Several medications, including doxycycline, atovaquone/proguanil, mefloquine, and primaquine, have proven effective.
But malaria is one of nature's most resilient killers, and the Plasmodium parasite is becoming resistant to these older medications. A promising new drug, artemisinin, has been synthesized from a plant used as a treatment in China for centuries. Demand for artemisinin currently far outstrips supply, and costs of the treatment remain beyond the reach of many malaria victims.
About 99 percent of mosquitoes carrying the malarial parasite are night biters, so for travelers and native populations alike, netting treated with insecticide for sleeping areas is crucial. In the absence of an effective mosquito-elimination method, netting can prevent many of the one million malaria deaths of children under 5 each year, and save many adults from unnecessary illness and death as well.