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Contact Us Fall 2001; Volume 2, Number 2
In Focus

Eradicating Malaria: High Hopes or a Tangible Goal?

Ilana Brito

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Malaria is a disease known well by name, but not by face. Most per- sons living in an industrialized country have never had, nor seen this serious disease. During the rainy season in malaria-endemic regions, individuals can receive as many as 300 mosquito bites per month. In such tropical areas, it is normal for ten percent of all mosquitoes to carry Plasmodium, the single-celled parasite that causes malaria. In Africa, where over eighty percent of malaria cases occur, Anopheles mosquitoes (the vector responsible for transmitting the malaria parasite) make up the bulk of the entire mosquito population. After calculation, the odds of being infected with plasmodia are practically all to none. Once transmitted, Plasmodia first hide in the liver and eventually invade and attack red blood cells, causing fevers, shakes, comas or convulsions, and occasionally, death. Today, malaria continues to plague children and adults throughout the world. Those without any built-up immunity to malaria, i.e. young children and tourists visiting malaria-endemic regions, face the highest risks of dying. While tourists can take prophylaxis to prevent contracting malaria, children are completely exposed once the short-lived immunity inherited from their mothers wears off. Each year in undeveloped nations, malaria takes the lives of more than 1.2 million children, at an average of 2,800 deaths per day. This daily death toll is thirty times that of the entire 1995 outbreak of the Ebola virus in Zaire. Five hundred million people, just fewer than ten percent of the world’s population, suffer from malarial fevers. In addition, malaria collectively drains national economies of more than $13 billion per year.

The Threat of Malaria

The threat of malaria continues to grow over time. Initial efforts to eradicate malaria by using insecticides were unsuccessful, merely resulting in insecticide-resistant strains of mosquitoes. Now, cheap and easily available drugs that were once effective against malaria often fail. Changing climates and increasing long distance travel can increase the population at risk. The resources once used to control malaria are no longer effective. In the early 1950s, scientists, policymakers and doctors thought they had the solution to control malaria, a disease that first appeared before Hippocrates’ time. The World Health Organization (WHO) initiated a program to globally eradicate malaria by using a new chemical against Anopheles mosquitoes: dichloro-diphenyl-trichloroethane, commonly known as DDT. The objective seemed clear: simultaneous extermination of the vector for the disease and the parasite. Despite political debates about the use of insecticides after the 1962 publication of Rachel Carson’s book, Silent Spring, DDT provided the single greatest hope for defeating this disease that, at that time, was one of the top killers in the world. For more than ten years, the WHO’s Global Eradication of Malaria Programs spent more than one billion dollars on spraying fields throughout malaria-endemic regions and coating pools of standing water where Anopheles mosquitoes lay their eggs; but the program was finally abandoned in 1972. The program succeeded in some areas, such as Sri Lanka, where malaria deaths went from 1 million cases per year to a mere 17. However, the persistent use of DDT had artificially selected mutant mosquitoes that were resistant to the insecticide. A parasitic species that had evolved over more than three or four thousand years was not going to die out that simply. Other attempts at controlling mosquito vectors have been made using Bti, a bacteria capable of destroying mosquito larvae, but whether it is ecologically feasible remains questionable. Pesticides alone could not solve this age-old problem. Even if mosquito populations are severely reduced for a short period, it may not prevent malaria from reemerging. After all, malaria parasites normally survive months of unsuitable conditions during the dry season and then reappear when the rain returns. That was the last notable malaria eradication effort. Wiping out malaria seemed too difficult a task, so more achievable goals were set in its place. Reducing the malaria caseload became the international objective. People were encouraged to use insecticide-treated bed-nets and to spray insecticides around their homes. Women were encouraged to take prophylaxis during their pregnancies to prevent infection. Control increasingly relied on medication rather than controlling mosquitoes. Unfortunately, medication could no longer protect individuals either. Parasites throughout the world independently developed resistant strains to our most effective medications. Although quinine, an extract from the bark of the Peruvian cinchona tree, was used to effectively treat malaria for more than 350 years, it was difficult and costly to extract, caused severe side effects and, at one point in time, its production caused the near extinction of the cinchona tree. Instead, almost immediately after, chloroquine, a substance sharing the same basic chemical structure to quinine, was synthesized in 1943. It was put to use because of its low manufacturing costs. Its misuse led to the independent emergence of drug-resistant strains of Plasmodium falciparum parasites throughout the world as early as 1965. Overusing chloroquine, using poorly manufactured chloroquine, failing to take the complete cycle of treatment, or using chloroquine alone in one given region has allowed plasmodium to develop resistance mechanisms. In some parts of Africa and Southeast Asia, over fifty percent of malaria cases are caused by resistant strains. While other drugs do exist, they are often too expensive to manufacture and distribute to the developing world. The only other cheap, available treatment is Fansidar, a mix of pyramethamine and sulfadoxine, but parasites have developed resistance mechanisms against it as well. The lack of practical medications has made malaria virtually uncontrollable in many parts of the world. Over ninety countries are now hotspots for malaria, with 2.4 billion people at risk (40 percent of the world’s population). That number is likely to grow with the onset of global warming. Climates once unsuitable for Anopheles mosquitoes now permit the growth of mosquitoes and their guests, the malaria parasites. The southwest United States is currently experiencing such changes. Intercontinental travel increases the chances of bringing infected mosquitoes to untouched sections of the globe. The appearance of West Nile encephalitis in the New York metropolitan area and Florida are other key examples.

Reconsidering Third World Problems

Contrary to other widespread killers, such as cancer, the pathology of malaria is well known and yet, it persists. Malaria existed in the United States from colonial times into the 1950s, but with eradication efforts, improved medical care, available drugs, and higher standards of living, malaria disappeared. Likewise, malaria was eliminated from many industrialized nations, including the Soviet Union, Italy and Canada. Unlike AIDS, which plagues the entire world, malaria is now strictly a developing world disease, and, consequently, no longer receives the funding needed for its control. For example, in 1993, $84 million was spent to fight malaria, while forty times this amount was spent on cancer. As of 2000, New York alone has spent more than $30 million trying to control the outbreak of West Nile encephalitis during which 7 people died and 62 people became ill. One can imagine that if the problem of malaria had been addressed earlier, the disease might have been eliminated from a larger section of the globe or a vaccine might have already been made available. Perhaps with the growing danger of malaria to the populations of industrialized countries, they too will begin to take notice. Fresh efforts aimed at controlling the disease have recently been adopted, such as cheaper, faster diagnostic tests, new drug options, education efforts, and prevention campaigns supporting the use of bed-nets to keep out mosquitoes. Some programs start early in people’s lives - educating them in attempt to dispel local folktales about a bird that steals the breath away from sleeping children and is responsible for the shakes, convulsions, and comas caused by severe forms of malaria. Countries have begun collaborating to combine research efforts and to support international malaria prevention campaigns. Examples include the World Bank’s Roll Back Malaria program, which aims to cut the number of worldwide malaria cases in half by 2010, the Bill and Melinda Gates Foundation’s Malaria Vaccine Initiative, Multilateral Initiatives on Malaria, and the World Health Organization’s Medicines for Malaria Venture. Without reliable vector control or medication, what hope remains for controlling the disease aside from individual and local efforts? With more money now going to scientific research on malaria, innovative solutions are close at hand. A vaccine is more possible now than ever before - scientifically and financially.

Viability of a Vaccine

Malaria has momentarily been eliminated from certain regions, but is it possible to completely eradicate malaria? Eradication, in its purest definition, means to permanently reduce the worldwide incidence of the disease to zero, while elimination signifies a reduction within a defined geographic area. Elimination requires continued efforts to contain the disease and prevent its reestablishment within the given area. So far, smallpox has been the only disease eradicated by human efforts.

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