Taking the battle to Mekong
- The fight against malaria has reached a critical moment as we face the prospect of a resurgence of the disease
Oct 3, 2017-Malaria infected more than 200 million people in 2015, and killed more than 400,000, most of them children in Africa. As devastating as those numbers are, they were a major improvement: Deaths fell by 48 percent since 2000. This impressive drop was the result of billions in funding and decades of effort by thousands of people across the globe.
But those impressive gains are at risk. The fight against malaria has reached a critical moment. We now face the prospect of a resurgence of the disease. Strains that are resistant to multiple drugs have appeared in Southeast Asia, and could spread to Africa, where they have the potential to cause a deadly catastrophe. This has happened at least three times before, and conditions are ripe for it to happen again.As someone who has had malaria four times, I know the awful power of this disease. I remember how grim the situation was in Africa in the 1990s when two of the most used medicines then, chloroquine and sulfadoxine/pyrimethamine, were failing. A sense of hopelessness was felt by the people living with malaria and those of us working to stop the disease. We had to accept a daily disaster—as a colleague of mine has put it, a 747 full of African children crashing into a mountain every three hours, day and night, for years on end. With an enormous amount of work, we managed to reduce this carnage to something less horrible. But I don’t ever want to go back to those days.
Malaria is transmitted to humans (and other animals) by infected mosquitoes, who inject malaria parasites into the bloodstream. The parasites spread throughout the body and multiply exponentially, causing chills, fever, headache, nausea and intense fatigue. Over the last century, researchers have developed effective medicines for malaria, including quinine, chloroquine, sulfadoxine/pyrimethamine, mefloquine, and artemisinin. When taken promptly, those drugs killed the parasites before they killed their host. Unfortunately, as usually happens in the battle between microbe and human, the malaria bug has evolved and developed resistance to our medicines. As a result, malaria has been beaten back in several places over the last 75 years, only to spread again, more lethal than before because the drugs no longer work.
Frequently, drug-resistant strains have originated in the Mekong region of Asia, an area that includes Myanmar, Thailand, Cambodia, Laos, Vietnam and the Yunnan Province of China. We are not sure why it starts there; it is likely a combination of factors. The parasites that circulate in the region may be able to mutate especially quickly. The region draws tens of thousands of migrants, who come for work on rubber plantations and in other industries, and who are particularly susceptible to malaria since they have lower levels of natural immunity. Because of widespread poverty, as well as lack of health care and education, those who get sick often use less medicine than they should, or use counterfeit drugs; both practices spur drug resistance.
Once drug resistance appears in the Mekong region, it spreads, often with ghastly results. In the 1950s, chloroquine-resistant malaria jumped to India and Africa, killing millions. Researchers, drug companies and public health officials came up with a replacement by combining two existing drugs, but then in the 1970s, parasites resistant to the sulfadoxine/pyrimethamine combination appeared in the Mekong and spread globally, rendering the treatment useless.
Since the late 1990s, we have relied on a drug called artemisinin, which is the best treatment we have ever had for malaria. Much of our recent success against this disease reflects the power of this medicine. It kills the parasite quickly, with few side effects, and it has saved millions of lives. We have tried to forestall resistance by combining artemisinin with other drugs, much as we do when treating H.I.V. and tuberculosis, but the day of reckoning appears to be at hand.
Over the past decade, several studies have found widespread resistance to the artemisinin-piperaquine combination throughout Southeast Asia. At some spots in western Cambodia, more than 40 percent of people who received artemisinin drug combinations failed to clear the parasites from their blood, or got sick again soon after treatment ended. This is a clear and ominous sign that the parasites are becoming more resistant.
So now we stand once again on the edge of the precipice. This time the risk of untreatable malaria is even greater than in the past, because no new drugs are likely to be available in the next few years. It takes a long time for drugs to go through the development pipeline, and most of the leading candidates are close relatives of artemisinin, so the malaria-causing parasites will likely be resistant to those drugs as well.
The first response of the public health community was to try to contain drug-resistant malaria in the Mekong region where it originated, preventing its wider spread. But past experience shows that this is not easy to do, and we now have clear evidence that multidrug resistant strains have spread across hundreds of miles, crossing national borders. Even worse, new resistant strains are popping up repeatedly and spreading, in a lethal version of Whac-a-Mole.
Instead, we should focus on a more ambitious strategy: to eliminate malaria from the Mekong region. This will be difficult, because the areas with the highest rates of malaria tend to be poor, rural and underdeveloped. But with coordination, hard work and proper funding, we can achieve our goal. Malaria has been eliminated from many regions where it was once common: the Southern United States, Russia, southern Europe, the Middle East and, most recently, Sri Lanka. There is no reason we can’t do the same in the Mekong region.
A broad consensus has emerged that elimination is the best strategy. The World Health Organization; the Global Fund to Fight AIDS, Tuberculosis and Malaria; the President’s Malaria Initiative; the Bill and Melinda Gates Foundation and others, have all expressed their commitment to this approach, as have the countries in the region.
Elimination will require a coordinated attack using all the weapons at our disposal. We know we can eventually eliminate malaria from the region by using the currently available anti-mosquito and anti-parasite measures, including insecticides and bed nets, plus medicines and diagnostic tests. Eliminating multidrug resistant malaria from the Mekong before it spreads to Africa will require so-called elimination accelerators, including highly sensitive new tests to identify symptom-free carriers of malaria infection, and mass drug treatment of infected groups or populations.
We also need closer cooperation from American and European health officials, international health agencies and financers, local nongovernmental organizations and especially from the inhabitants and governments of the Mekong region. We must ramp up quickly; drug resistance is spreading; if it spins out of control, we run the risk of a huge resurgence of malaria in other parts of Asia and especially in Africa.
—©2017 The New York Times
Published: 03-10-2017 08:13