Containing Drug Resistant Malaria: the Risks of Weak Health Systems

March 07, 2011

For decades, the global health community has sought affordable drugs to obliterate malaria-causing microbes - which include strains so virulent and fast acting they can kill a child the same day symptoms appear. Africans are the most in need of effective drug therapies because they are the hardest hit, absorbing 90 percent of the world's nearly one million malaria-related deaths each year, and over 80 percent of the roughly 300 million annual cases. For the people of Africa, one recently available class of drugs has been a game changer. It comes from an herb called artemisia and, with the support of donor programs, has helped halve malaria-related child mortality in many communities.

But artemisinin-based drugs are like all other anti-malarials; they're extremely vulnerable to drug resistance. This is because the parasites that cause malaria quickly evolve biological strategies to survive treatments. These microbes have neutralized the effectiveness of every drug put to use in global health programs - from the oldest one, quinine, to the gold standard developed during World War II, chloroquine, and everything since. The World Health Organization's investigation into the artemisinins in the 1990s (which the Chinese had discovered in the 1970s) was a major breakthrough. Because of unprecedented efforts in the last few years to make them affordable for use in health assistance programs, they are now the frontline defense against malaria in 42 African countries. Their importance to global health assistance programs, recipient governments, NGOs, and the sick cannot be overstated.

For these reasons, global health experts lost sleep last month when Cambodian and Thai troops exchanged fire over a land dispute in a forested border region that is home to the world's only confirmed artemisinin-resistant strains of malaria. A tentative ceasefire has been worked out. But troop movements continue and an estimated 30,000 residents had fled for safer ground. International interventions seem unlikely to resolve the dispute, which involves ownership of an 11^th-century temple. And soldiers and civilians continue to move in and out of the area, exposing themselves to these unique strains of malaria and running the risk of carrying the microbes to new regions.

Robert Newman, director of the Global Malaria Programme for the World Health Organization, told the United Nations humanitarian news service IRIN that concerns about the Cambodian-Thai border dispute potentially unleashing these strains on Africa "wake me up at night" and would amount to a "public health disaster."

In Asia, drug resistant strains of malaria are slow moving, like a brushfire - moving toward ecosystems and economic conditions capable of supporting transmission. Malaria-carrying mosquitoes, called anophelines, thrive throughout the world but contribute to malaria transmission only where governments fail to maintain adequate health systems and impoverished people live in mosquito-porous dwellings, often made of mud and sticks. The most intense transmission zones in the world are found in sub-Saharan Africa because of crushing poverty and the presence of the world's most efficient malaria-carrying anopheline mosquitoes. In some parts of Kenya and Tanzania exposure rates have been measured at 1,000 to 2,000 infectious bites per person per year - or 3 to 5 per day! Artemisinin-resistant strains in these areas would spread rapidly, like wildfire.

Artemisinin-resistance first cropped up in Cambodia in 2009. Since then, the global community has closely watched a pattern of resistance growing along Cambodia's malarious borders then transiently appearing in other impoverished areas, including Vietnam and along the Myanmar-China border. Countries with stronger health systems, like Thailand, are not as worrisome because they are able to detect, quickly treat and contain their malaria outbreaks. These other countries, with fragmented public health systems, are the real threat.

Artemisinin-based drugs are distinct and valuable because they act so rapidly against infections. This allows them to be combined with older, slower-acting drugs in a way that sustains therapeutic levels of treatment in the blood long enough to kill off an infection. But artemisinins are also politically important; they are needed to keep anti-malaria programs viable while health assistance programs await a workable malaria vaccine. That could take another 10 years, which means international stakeholders will have to do a better job of containing resistance than any other generation before them.

In January, WHO and Roll Back Malaria announced the creation of a $175 million fund to help pay for containment plans wherever artemisinin-resistant strains crop up, with a specific goal of preventing them from moving into Africa. The cost is estimated at US$10-20 per person along the Cambodian-Thai border and US$8-10 per head in the at-risk areas of the Greater Mekong region. When the plan was announced, Margaret Chan, WHO director-general, warned that the "usefulness of our most potent weapon in treating malaria is now under threat" and that the consequences are too great to not act.

The sad truth, however, is that resistant strains might currently be evolving somewhere on the African continent. As in Cambodia, many African governments lack the resources or political will to build tight health systems capable of delivering treatments directly to people. They also lack adequate controls to ensure drugs are used properly and are protected from corruption, like theft and counterfeit. Counterfeit anti-malarials are especially troubling because a severe scarcity of health professionals has forced donor programs to make these drugs available over the counter at barely regulated kiosks whose owners operate under little or no oversight. Too often medicines are diluted or falsified to maximize profits. The sick receive inadequate doses that fail to clear the infection, creating conditions for resistance.

Over time, long-term solutions must target the root causes of drug resistance. This will require a retooling of all global health spending so that more money and political might are put toward building stronger health systems and health-based infrastructures; reversing the severe scarcity of health professionals in rural areas; securing drug supplies against corrupt practices; and boosting woefully inadequate healthcare services for impoverished people in malaria-prone places. 

Photo Credit: female Anopheles albimanus mosquito while she was feeding on a human host, (CDC  photo: #7861)

http://en.wikipedia.org/wiki/File:Anopheles_albimanus_mosquito.jpg