An Unending Epidemic   Page 1Page 3

Malaria, unlike most major diseases around in the 19th century, has not steadily declined throughout this century. Though malaria was largely suppressed throughout the world in the 1960s and 1970s, it sprang back with a vengeance over the last fifteen years. The number of reported cases has almost doubled, making it the third largest infectious disease in the world. Scientists estimate that last year alone upwards of 300-500 million people contracted malaria and well over a million people, mostly children, died from the disease. (World Health Organization, 1999)

For those areas affected by the disease, the economic impact is enormous. Each time a person gets the disease they can expect to miss 5-20 days of work, and chronically infected families on average lose more than twenty five percent of their yearly income. In the countries where the disease is a nationwide epidemic, malaria patients occupy 3 out of 10 hospital beds, and the net effect can be a 5 percent drop in the nation’s Gross National Product. Collectively, the direct and indirect costs of malaria for these mostly poor, third world countries are well over $2 billion a year. (World Health Organization, 1998)

The main reason malaria is so hard to control has to do with the nature of the disease and the way it is spread. Malaria is neither a virus nor a bacterium, but a one-celled parasite. The parasites breed in and are transmitted by mosquitoes. When the mosquito bites a person, the parasites get into the new host's bloodstream through the mosquito's saliva. From there the parasites head directly for the liver. To insure their success in infecting the human body, they further multiply in the liver cells for 9 to 16 days. They then pour out into the blood stream and begin feeding on red blood cells. (World Health Organization, 1998)

  Feeding Mosquito
Malaria parasites are transmitted to humans by mosquitos. A mosquito ingests parasites when it bites an infected person, and will infect anyone it bites later. The cycle of malaria transmission can be broken by killing mosquitos in epidemic regions, or reducing the number of hosts of the disease. (Photograph copyright BIODIDAC, University of Alberta)

Growth of Malaria Parasites

To date there is no reliable vaccine for any type of parasite. The genetic code of parasites is much more complex than most viruses or bacterium. The malaria bug adapts quickly to vaccines and even some cures, and the human body develops a partial resistance to the disease only after repeated attacks. There are drugs such as quinine and chloroquine that kill the parasites once they have infected a person, but these chemicals are expensive and people must take them continuously to stave off the disease. (Shell, 1997)

Another problem with malaria is that it uses the mosquito as a delivery system. Even when a malaria victim is isolated, the disease can carry on. Often people don't even know they have it. Since the parasite runs rampant in the bloodstream, symptoms can include everything from muscle ache, to fever, to jaundice to dementia. In mild cases many just chalk the disease up to the flu and do not seek treatment at all. (Shell, 1997)

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  From left to right, increasingly mature malaria parasites. These parasites grow in red blood cells, progressing through several stages of maturation, until they rupture, spreading more parasites throughout the victim. (Illustrations from Coatney GR, Collins WE, Warren M, Contacos PG. The Primate Malarias. U.S. Department of Health, Education and Welfare, Bethesda, 1971)
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