Drug resistant malaria is a problem. These parasites – Plasmodium spp. – become resistant to a drug after exposure to it: in any population, some individuals will survive longer when exposed to a threat. Perhaps the drug is not there in sufficient quantity, or perhaps it is not used for long enough, and a few survive. If their ability to survive the threat can be passed on genetically, the next generation will be likely to acquire resistance: the next time the threat appears, even more will survive. Repeated exposure to a drug actually selects resistant individuals and favors their success.
In time, resistance to all antimalarial drugs appears. Historically, it has appeared first in Southeast Asia – along the international borders of Thailand – with unsettling regularity. In The Coming Plague (1994), Laurie Garrett wrote that “social conditions in Southeast Asia… led to the downfalls of chloroquine, halofantrine, mefloquine, quinine, Fansidar, proguanil, and every other antimalarial.” What is so special about Southeast Asia?
What causes drug resistant malaria?
Wongsrichanalai et al identify two key scenarios that ultimately lead to the appearance of Plasmodium spp. that are resistant to drugs:
- The disease is treated and the patient feels better, but the drug is discontinued before all the parasites are dead, leaving a small population to reproduce and give rise to a large population of resistant organisms.
- The infection is completely cured, but the patient is reinfected before all of the drug has been cleared from the bloodstream. Sensitive organisms will die, while the more resistant ones survive to reproduce.
These are scientific explanations, but a myriad of related factors help create the conditions for malaria drug resistance to appear including:
- lack of health care
- poverty
- war and social upheaval
- mass migration of people
- black market drugs
Malaria drug resistance and the Thai-Cambodia border
In 1957, resistance to the antimalarial drug chloroquine appeared in the Thai-Cambodia borderlands. At that time, Thailand and Cambodia were on poor terms politically and there was a territorial dispute involving part of this border. Antimalaria campaigns in Thailand had failed to control the disease in this politically unstable area and health care was basically absent. It’s easy to see how these conditions led to inappropriate use of chloroquine, leading to drug resistance.
Chloroquine resistance spread from there and was to have a significant impact on the Vietnam War. The Vietnam War in turn, as well as the period of Khmer Rouge domination in Cambodia, kept the country’s economy and health care from improving: drugs for malaria were not used properly and many were produced and sold in the underground economy, where there was no control of quality. This is still true today: access to drugs, quality of drugs, and proper use of drugs are all compromised.
Wongsrichanalai et al describe the more recent historical conditions along the Thai-Cambodian border (northwestern Cambodia from the Gulf of Thailand to the border with Laos). In the late 1980s and early 1990s, there was mass daily movement of people across the border because of the opportunities provided by gem mining in Cambodia (Garrett points out that much of this movement was clandestine). Would-be miners came without immunity to malaria and quickly became ill. To get treatment they had to travel back to communities near the border; many reentered Thailand for treatment. If they recovered, they typically immediately returned to the mines, only to be reinfected.
Thailand’s borders breed drug resistant malaria
Thailand’s borders with Cambodia, Myanmar (Burma), and Malaysia have all produced drug-resistant malaria strains. All of these borders separate Thailand, a relatively peaceful prosperous country with good health care, from a country characterized by poverty, political instability, and social unrest. The last four decades have seen millions of people seeking to cross these borders, officially and unofficially, as a result of war, persecution, genocide, natural disasters, economic need etc. Thus, as Laurie Garrett correctly stated, the borderlands of Thailand are the perfect setting for the appearance of drug resistant malaria.
Today, the driving social forces may have changed, but the conditions remain. It’s no surprise, therefore, to see reports of malaria, resistant to the best therapy we now have, from the Thai-Cambodia border.
Related article:
Mosquito Borne Disease Prevention
Sources:
Chareonviriyaphap, Theeraphap, Michael J. Bangs, and Supaporn Ratanatham. 2000 "Status of Malaria in Thailand." Southeast Asian Journal of Tropical Medicine and Public Health 32: 2
Garrett, Laurie. 1994 The Coming Plague. New York: Farrar, Straus and Giroux.
Wongsrichanalai, Chansuda, Jeeraphat Sirichaisinthop, Jerome J. Karwaski et al. 2001 Drug Resistant Malaria on the Thai-Myanmar and Thai-Cambodian Borders. Southeast Asian Journal of Tropical Medicine and Public Health 32:1
Rosemary Drisdelle - Rosemary Drisdelle has been published many times as a nonfiction writer and several times as a poet. Her first book, Parasites: Tales of ...
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