Friday, September 4, 2009

Malaria and antibiotics

Malaria is a parasite that is transmitted by mosquitoes and infects a million people a year. Since this disease is not caused by a bacterium, how is it that antibiotics affect malaria and improve the health of sickened individuals?

From 1920 to 1950, antibiotics were a widely used treatment for malaria, although medical practitioners were not entirely sure why this treatment was so effective (Butcher). In the early 1980s, it was "discovered that antibiotics ... are active as antimalarial agents" (Oronsky). More recently, azithromycin [also called Zithromax] has been used to treat malaria in Ethiopia after it was shown "to have efficacy in the prevention and treatment of malaria due to both Plasmodium falciparum and Plasmodium vivax," (Travis).

After research, scientists have hypothesized that antibiotics treat malaria because they attack the plasmodia (a protozoa) within the parasites; therefore the antibiotics diminish the malaria" (Flam). Furthermore, antibiotics alleviate the immune system of other infections that may coexist with malaria.

"The treatment may also have unintended consequences...including the inducement of antibiotic resistance" (Travis). However, the situation is further complicated by the development of drug-resistant bacteria in malaria-infested areas that have had no exposure to antibiotics.

As mysterious as the seemingly unfounded effectiveness of antibiotics on malaria in the 20th century, the unexplained drug-resistant bacteria in "remote rainforest communities in Guyana" confounded scientists (Juncosa). New studies revealed "that overuse of a drug used to prevent and treat malaria may be contributing to growing antibiotic resistance...Drug-resistant bacteria are known to arise from the overuse of antibiotics, which is why researchers were surprised to discover that they can develop in areas that do not have access to" that particular antibiotic [ciprofloxacin]. Michael Silverman, "an infectious disease specialist at Lakeridge Health Network in Ontario" says that antibiotic-resistant E. coli were more widespread in these remote Guyanese villages than in U.S. hospitals "where every second person is on antibiotics." Silverman's study showed that the patients infected with drug-resistant E.coli had been "given the drug chloroquine to prevent and treat malaria" (Juncosa).

According to Silverman, "It is very possible that the antimalarial drugs may be inducing a large amount of the antibiotic resistance that occurs in the tropics." Unfortunately, "plasmodia, the causative organisms of malaria, have developed resistance to antibiotics" as well and "at the same time, the mosquitoes that carry plasmodia have become resistant to the insecticides that were once used to control them. Consequently, although malaria had been almost entirely eliminated, it is now again rampant in Africa, the Middle East, Southeast Asia, and parts of Latin America" (MSN).

The increasing number of drug-resistant strains of malaria parasite, plasmodia, and other bacteria is another reason why an effective malaria vaccine is so important. We cannot continue treating malaria in the ways that we have in the past, for very soon, these old methods will be rendered ineffective.

Butcher, Geoff. “Million Murdering Death.” History Today April 1998: 24-28.

Flam, Fray. “Scientists Find Weak Spot in Defense of Tenacious Malaria Parasite.” Tribune News Service November 1997: 26-28.

Juncosa, Barbara. "Antibiotic Resistance: Blame it on Lifesaving Malaria Drug?" Scientific American 21 July 2008.

MSN Encarta."Antibiotics"

Oronsky, Arnold L. Treatment of malaria with antibiotics. "United States Patent 4496549" 29 Jan 1985.

Science News. "Distribution Of Antibiotic For Eye Disease Linked To Low Death Risk Among Ethiopian Children." 1 Sept 2009.

Travis C. Porco; Teshome Gebre; Berhan Ayele; Jenafir House; Jeremy Keenan; Zhaoxia Zhou; Kevin Cyrus Hong; Nicole Stoller; Kathryn J. Ray; Paul Emerson; Bruce D. Gaynor; Thomas M. Lietman. Effect of Mass Distribution of Azithromycin for Trachoma Control on Overall Mortality in Ethiopian Children: A Randomized Trial. JAMA, 2009; 302 (9): 962-968

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