Nav: Home

New studies highlight setbacks and advances in global malaria fight

April 05, 2012

Emergence of resistance to the drug artemisinin in western Thailand has created a critical point in global efforts to control and eliminate malaria worldwide, according to a new study published in the Lancet, a British Medical Journal, by researchers at the Texas Biomedical Research Institute and their collaborators in Thailand.

A second study, published concurrently in the journal Science by the same research groups, identifies a major region of the malaria parasite genome associated with artemisinin resistance, raising hope that there will soon be effective molecular markers for monitoring the spread of resistance. Both the Lancet and Science studies were funded by the National Institutes of Health and the Wellcome Trust.

Malaria killed 655,000 people - over one per minute -- in 2010. While these numbers are high, malaria deaths have declined by 30 percent over the past decade, largely because of effective control using treatment with combination therapies containing artemisinin, a plant-derived antimalarial drug developed in China.

Patients infected with malaria parasites who respond poorly to treatment have been observed in Cambodia and stimulated a coordinated World Health Organization effort to eliminate the disease in this region. That effort was based on the premise that drug-resistant malaria was confined to Cambodia. Now that effort needs to be reassessed, the Lancet study concludes.

From 2001 until 2010, the Texas Biomed team and their collaborators in Thailand studied 3,202 patients in clinics located in Northwestern Thailand, 500 miles from the Cambodian focus. They observed a dramatic decline in the drug potency over that period. Further, by measuring drug potency in patients infected with genetically identical malaria parasites, they were able to show that the decline in potency results from the spread of resistance genes.

"Spread of drug resistant malaria parasites within Southeast Asia and overspill into sub-Saharan Africa, where most malaria deaths occur, would be a public health disaster resulting in millions of deaths," said Texas Biomed's Standwell Nkhoma, Ph.D., a lead author of the Lancet report. Resistance to other antimalarial drugs, such as chloroquine and fansidar, has previously spread from Southeast Asia to Africa, providing a chilling precedent for such a scenario.

"The problem we have is that treatment with artemisinin-based drugs will promote spread of resistance, but there are no viable alternative treatment options in Southeast Asia," said Nkhoma.

"Our group wanted to understand what genetic changes have occurred in these parasites," said Texas Biomed's Ian Cheeseman, the first author of the companion report in Science "This study narrows the search to a region of the parasite genome containing around 10 genes. We haven't yet found the precise changes involved, but we are getting close."

The researchers first compared genetic variants in the genomes of parasites from Laos, which are sensitive to the drug, with parasites from Cambodia, that show high levels of resistance and those from Thailand, where both resistant and sensitive parasites occur.

"We found 33 genome regions that were very different in parasites from these three countries" said Anderson "When we examined these regions in more detail in a large collection of parasites from Thailand, we found that one small section of malaria parasite genome on chromosome 13 is strongly associated with parasite resistance".

Identification of a molecular marker for resistance will be critical for monitoring the spread of resistance, for determining how resistance occurs, and for understanding the mechanism of action of the drug. The Science study narrows the search for such a marker, and provides an important advance in the race to avert a public health crisis.
Both reports resulted from an international effort led by Texas Biomed's Tim Anderson, Ph.D., and François Nosten, M.D., at the Shoklo Malaria Research Unit in Thailand, with collaborators at Notre Dame University and in Laos and Cambodia. The other Texas Biomed authors on the reports are Shalini Nair and Salma Al-Saai.

Anderson can be reached through Joe Carey at 210-258-9437 or

Texas Biomed, formerly the Southwest Foundation for Biomedical Research, is one of the world's leading independent biomedical research institutions dedicated to advancing health worldwide through innovative biomedical research. Located on a 200-acre campus on the northwest side of San Antonio, Texas, the Institute partners with hundreds of researchers and institutions around the world to develop vaccines and therapeutics against viral pathogens causing AIDS, hepatitis, herpes, hemorrhagic fevers, and a host of other illnesses. The Institute also has programs in the genetics of cardiovascular disease, diabetes, obesity, psychiatric disorders and other diseases. For more information on Texas Biomed, go to

Texas Biomedical Research Institute

Related Parasites Articles:

Deciphering plant immunity against parasites
Nematodes are a huge threat to agriculture since they parasitize important crops such as wheat, soybean, and banana; but plants can defend themselves.
Malaria parasites 'walk through walls' to infect humans
Researchers have identified proteins that enable deadly malaria parasites to 'walk through cell walls' -- a superpower that was revealed using the Institute's first insectary to grow human malaria parasites.
Scientists analyze dispersal of parasites by birds in the Americas
An international study investigates transmission of microorganisms that cause malaria and other diseases from migratory to resident avian species.
What's the buzz on bee parasites?
Published today in the open-access journal GigaScience is an article that presents the genome sequence and analysis of the honey bee parasitic mite T. mercedesae.
Major drug initiatives are best way to curb threat from parasites
Large-scale programmes to treat a life-threatening disease could improve the health of millions despite concerns about their long-term effects, a study suggests.
More Parasites News and Parasites Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#534 Bacteria are Coming for Your OJ
What makes breakfast, breakfast? Well, according to every movie and TV show we've ever seen, a big glass of orange juice is basically required. But our morning grapefruit might be in danger. Why? Citrus greening, a bacteria carried by a bug, has infected 90% of the citrus groves in Florida. It's coming for your OJ. We'll talk with University of Maryland plant virologist Anne Simon about ways to stop the citrus killer, and with science writer and journalist Maryn McKenna about why throwing antibiotics at the problem is probably not the solution. Related links: A Review of the Citrus Greening...