Malaria in Thailand
Air Date: Week of September 8, 2000
Some of the world’s leading malaria researchers are working in Thailand, along the country’s borders with Burma and Cambodia, studying the emergence of virulent strains of malaria. Orlando de Guzman reports on why scientists believe malaria is resisting current anti-malaria drugs and what treatments are currently being suggested.
CURWOOD: This is Living on Earth. I'm Steve Curwood. By the end of World War II, malaria had been eradicated from just about every industrialized nation. Even in less-developed lands, including Thailand, South Africa, and Kenya, health officials were able to bring the disease under control with quinine and other drugs. Now, things have changed. New, more drug-resistant strains of malaria are emerging, and last year about two million people died from the disease. Today the World Health Organization says malaria threatens nearly 40 percent of the world's population. Orlando de Guzman reports from the border of Thailand and Burma, a place called the global epicenter for new strains of the disease.
DE GUZMAN: Along the Dawna mountain range dividing Thailand and Burma, outbreaks of malaria come with the monsoon season from May to September. This is when mosquitoes breed easily in the dense jungle along the border. In this vast frontier, most people eke out a living planting rice and corn along the rugged foothills. Venture further into the forest and you enter a no man's land. It's home to heavily armed drug cartels and illegal loggers. Countless land mines litter the border.
DE GUZMAN: This area is notorious for the most potent strains of malaria on earth. For villagers living here, malaria strikes hard and fast.
MASU SU: (speaks in native language)
TRANSLATOR: She go to the forest, she said, for the six day, for six days, then she feeling hot, hot, so she not feel good condition so she come here.
DE GUZMAN: Twenty-five-year-old Masu Su was unconscious when she was carried for six hours from a logging camp inside Burma. Her family brought her to the village of Mokothai, a cluster of bamboo huts with a clinic on the Thai side of the border. A serious case of cerebral malaria has left her shivering beneath a wool blanket despite the tropical heat.
MASU SU: (Speaks in native language)
TRANSLATOR: Before the chest pain, and the headache, and the dizziness, especially in the night time, with fever and she's not feeling good.
(Voices; a child screams)
DE GUZMAN: Malaria is caused by a blood-borne parasite that's transmitted through the female anopheles mosquito. Once a person is bitten, the parasite quickly retreats to the liver, where it grows and multiplies. It's not until the parasites emerge and spread into the bloodstream that painful symptoms appear. In a matter of hours the parasite can copy itself thousands of times, thrashing about and popping red blood cells.
DE GUZMAN: At a clinic for Burmese refugees in the Thai trading down of Measot, malaria is the most common illness. Aung Moon, the medic on duty, says political instability within Burma is causing the disease to spill over into Thailand.
MOON: (Speaks in Burmese)
TRANSLATOR: Malaria is a big problem along the border, especially inside Burma, where they don't have clinics and doctors. These refugees don't know enough about malaria to take simple precautions, like using mosquito nets. When they get infected, they just buy a pack of painkillers. That's one reason why malaria is so high on the border.
DE GUZMAN: Aung Moon says refugees, mostly ethnic Karens, often get sick in their long trek through malaria-infested jungles to escape the Burmese army. The Thai government says this is why malaria cases have risen by 20 percent along the border since the mid-1990s. Although malaria is on the rise, Thailand shares a very small percent of the worldwide burden. Nine out of ten cases of malaria are in Africa. What's unique about Thailand is the strength of the parasite. Three of the most common anti-malaria drugs are useless here. Even quinine, an old ally used to fight severe malaria, is losing its punch, says Aung Moon.
MOON: (Speaks in Burmese)
TRANSLATOR: What's really scary is that more and more people are becoming resistant to quinine, the most common and powerful drug we have been using. Even when we give quinine to them, the parasites are still there in their blood.
DE GUZMAN: Resistance to drugs comes primarily from incorrect use. When a drug is taken irregularly or in low doses, not all of the parasites are killed off. The stronger pathogens that survive are then allowed to replicate. Quinine resistance was first documented in Thailand in the late 1980s, and researchers are closely monitoring its spread. There are fears that quinine resistance may move beyond Thailand into India and Africa. That's already happened to chloroquine, a synthetic and cheaper alternative. Dr. Francois Nosten is with the Shoklo malaria research unit. He's been tracking drug resistance along the border of Thailand since the early 1980s.
NOSTEN: The first case of chloroquine resistance was documented in 1957. Ten years later it has spread over the whole region, and in the middle of the 1980s it had already reached Africa. For certain drugs it's not a very quick phenomenon, but for other drugs the emergence of resistance is much quicker.
DE GUZMAN: In Thailand, for instance, it took only five years for the malaria parasite to become resistant to mefloquine, a drug developed by the U.S. Army. More alarming, says Dr. Nosten, is what happened to another drug called fancidar. The drug is an effective treatment in Africa. But in Thailand, the parasite became resistant to fancidar within two years.
NOSTEN: So it's a very clever organism and the type of parasite that we find in Asia is more capable of adaptation to its environment. But the exact, precise mechanism of how the parasite does all this, we don't know.
DE GUZMAN: Not only has the malaria parasite figured out how to escape the action of various drugs, it's also learned how to hide from our immune system. People who are infected with the disease never develop full immunity. Just how the parasite does this is key to developing a vaccine against malaria.
DE GUZMAN: In an air-conditioned laboratory in Bangkok, Major Scott Miller from the U.S. Army is trying to unlock the biological underpinnings of the most deadly strain of malaria, plasmodium falciperum.
MILLER: These are our incubators. They are incubated at 37 degrees Celsius, which is roughly the temperature of the human body, where we grow malaria parasites in the laboratory.
DE GUZMAN: The U.S. Army is trying to develop a vaccine in case its troops are deployed in tropical countries. Dr. Miller says the U.S. Army is now less prepared to fight malaria than it was during the Vietnam War 20 years ago.
MILLER: Drug resistance in Southeast Asia is such that all of the drugs that are available on the U.S. formulary are ineffective, both in the prevention and to a large part of the treatment of falciperum malaria here. Therefore, if we had a large number of people come who were not immune to malaria, it is likely that malaria would be a serious illness that would affect those soldiers.
DE GUZMAN: Vaccine trials have been carried out in Thailand and in Gambia in West Africa, and so far results have been mixed. That's because once inside the body, malaria pathogens are able to change their appearance regularly, so the vaccine can't recognize them. The parasite is also extremely complex, containing a thousand times as many genes as HIV.
MILLER: The malaria parasite has been with humanity for many thousands of years, and it has proven to be a very difficult adversary, both in terms of our understanding the immune response that our body makes once we are infected with malaria, and also in terms of developing a vaccine against the parasite.
DE GUZMAN: With an effective vaccine a long way off, Thailand is relying on a promising anti-malaria drug called artemisinen. The drug is extracted from the wormwood plant. Highly effective, artemisinen has actually been used to treat fevers for over 2,000 years in China. In Thailand, artemisinen is used in combination with mefloquine. Dr. Nicholas White, a professor of tropical medicine at Oxford University, says the results were dramatic.
WHITE: In the mid-1990s it was really looking rather serious that we might be confronting completely untreatable malaria by this new millennium. But fortunately for us, a solution has come in the use of combination drugs. And this approach has prevented the emergence of resistance.
DE GUZMAN: That's because two drugs working together can kill off the infection completely. While combination drug regimens are highly effective, Dr. White remains cautious.
WHITE: I think it would be very unwise to consider that resistance would not develop to any chemical that an organism is exposed to. Every time we have thought resistance would not develop in a microorganism that causes an infection, we're wrong.
DE GUZMAN: Although Thailand has the misfortune of having the most drug-resistant strains of malaria, it does have the political will and health infrastructure to deal with the problem.
DE GUZMAN: Educational campaigns through songs and posters make their way to the village level quickly and have raised the public's awareness about the disease. The country's successful malaria eradication efforts have confined drug-resistant strains to small, isolated pockets, mostly along its borders. Dr. Krongtong Thimarsarn, the director of Thailand's malaria control program, says it's important to think of malaria not just as a health problem.
THIMARSARN: In my country, I think the government considered malaria was the top priority among the diseases, because they consider that malaria is the barrier for improvement of the socioeconomic status of the country. So the best way is to get rid of the enemy.
DE GUZMAN: Thailand's successful campaigns to control malaria have not been so easily repeated by neighboring Burma and Cambodia. But the biggest fear now is that Thailand's newer, drug-resistant strains are slowly making their way to sub-Saharan Africa. It's happened before, but this time the effects are predicted to be much more devastating. For Living on Earth, I'm Orlando de Guzman in Bangkok.
CURWOOD: One footnote to our story. Recently there has been a lot of concern about the spread of malaria related to global warming. A new study out of Oxford University says that as the world heats up, places where malaria exists will shift over the next 50 years. Some places that are presently free of the disease, including parts of Mexico and the southern United States, will likely see outbreaks. But other regions, including parts of Brazil, Bolivia, and the Horn of Africa, are predicted to become malaria-free.
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