Malaria Gaining Resistance to Best Available Treatment

By Nathan Seppa, Science News

WASHINGTON — Malaria that is resistant to the best available drug is more widespread in Southeast Asia than previously reported, new research shows. The worrisome finding poses a risk that travelers could carry this strain of the malaria parasite to other parts of the globe and unwittingly spread it, scientists reported Nov. 19 at a meeting of the American Society of Tropical Medicine and Hygiene.

The frontline drug in question is called artemisinin, the most potent medication currently in use against malaria. Signs of malarial resistance to artemisinin have surfaced over the past several years in Cambodia (SN: 11/22/08, p. 9). The new findings confirm that resistant malaria has now cropped up beyond a spot on the border of Thailand and Cambodia where it was initially detected. Now it has appeared in Vietnam and in two spots along the Burma border with Thailand and China.

“Things are changing. There’s no doubt the signs are concerning,” said Robert Newman, director of the Global Malaria Programme at the World Health Organization in Geneva. But he added that these signals are early and need further verification.

Patients in these areas take longer on average to overcome a malaria infection when given a standard combination of artemisinin and another antimalarial. This lag results from slower clearance of the malaria parasites from the blood, said WHO’s Pascal Ringwald, a medical officer who presented the update.

Patients who remain ill for longer stretches despite treatment need extra medication to recover from malaria and are also more likely to have severe or fatal cases, Ringwald said.

Malaria is caused by a single-celled parasite that infects the blood. Symptoms include fever, headache, chills, anemia and a swollen spleen. Of the more than 350 million people who come down with malaria worldwide each year, up to 1 million die. Mosquitoes spread the parasite from person to person.

Malaria has a history of becoming resistant to drugs, and artemisinin now risks becoming the most recent addition to that list. The new reports are disheartening to doctors because artemisinin normally packs a considerable wallop. Although artemisinin is a short-acting drug that gets cleared from the body in a few hours, it makes the most of its time — driving down parasite levels dramatically.

Using artemisinin alone invites resistance. So the standard therapy teams it with one of the longer-acting drugs, which perform mop-up duty on the remaining parasites, said Christopher King, a physician and epidemiologist at Case Western Reserve University in Cleveland.

The new flashes of resistance may have arisen because combination treatment isn’t always available. And since artemisinin can be bought over the counter in many parts of Asia, people seeking relief don’t always follow the WHO guidelines of pairing artemisinin with another drug, King said.

Also, taking artemisinin for a fever that isn’t caused by malaria can allow resistant strains of the parasite to take hold, Newman said.

In the past, malaria’s resistance to other drugs has been linked to specific genetic changes in the parasite. The precise mechanism underlying resistance to artemisinin is still unsolved, King said.

Artemisinin is derived from extracts of the sweet wormwood bush. The bush’s leaves have been used as a folk remedy against fevers for roughly 2,000 years in Asia but fell out of use in the 20th century with the introduction of modern antimalarial drugs such as chloroquine.

During the Vietnam War, North Vietnamese leader Ho Chi Minh appealed to China for traditional remedies for soldiers who had malaria. Tea made from sweet wormwood leaves worked and ultimately became the basis for artemisinin drugs. It’s not clear whether parasites in Southeast Asia are the first to become resistant because they have had a long history with artemisinin, or if other factors are involved, Newman said.

Image: Malaria from Plasmodium falciparum. Flickr/Got_Jenna

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Evolution and history compulsory

Evolution should be taught early, scientists advised

Primary school children in England will have to learn about evolution and British history under a shake-up of the national curriculum.

Schools Minister Vernon Coaker says the subjects will be compulsory elements of a new primary school curriculum being introduced in 2011.

Scientists and humanists had lobbied ministers for the inclusion of evolution in the theme-based timetable.

History is already compulsory, but there were fears it would be sidelined.

Schools will not be told which parts of British history to teach.

Earlier this year, when the curriculum changes were announced, critics complained that children would learn more about the internet than history.

Ministers say they want to "reinforce" history by making it a statutory element of the new primary curriculum.

Campaign

The curriculum is set out in a new education Bill just introduced to Parliament.

It was drawn up after a review by Sir Jim Rose, which called for distinct subjects to be replaced by six new "areas of learning".

Mr Coaker said: "What and how our children learn lies at the heart of our policies to raise standards.

"We've seen that an inspiring and rigorous curriculum can transform failing schools, which is why these plans are based on the very best practice from this country's top-class teachers."

He added: "Teachers will have more freedom to use their professional judgement and creativity to make links between subjects that make sense to their pupils: from linking history to the arts, or science to PE."

Evolution is arguably the most important concept underlying the life sciences Andrew Copson, British Humanist Association

The British Humanist Association (BHA) had led a campaign to have Darwin's theory of how life evolved through natural selection made a compulsory element of the new primary curriculum.

It organised a public letter signed by more than 500 from scientists and supporters.

Andrew Copson of the BHA said: "This is excellent news. Evolution is arguably the most important concept underlying the life sciences.

"Providing children with an understanding of it an early age will help lay the foundations for a surer scientific understanding later on."

He added: "Public authorities clearly need to do more to tackle the growing threat to the public's understanding of science from creationist-inspired beliefs and other pseudoscience".

Evolution is already taught in secondary schools and many primary schools, but under the curriculum changes, it will become compulsory for primary pupils, with the recommendation that they are taught the subject in their later years at school.

The new curriculum says schools must "investigate and explain how plants and animals are interdependent and are diverse and adapted to their environment by natural selection".

Professor Sir Martin Taylor, vice-president of the Royal Society, said: "We are delighted to see evolution explicitly included in the primary curriculum.

"One of the most remarkable achievements of science over the last two hundred years has been to show how humans and all other organisms on the earth arose through the process of evolution."

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Extinction of Giant Mammals Changed Landscape Dramatically

By Jeanna Bryner, Senior Writer

The last breaths of mammoths and mastodons some 13,000 years ago have garnered plenty of research and just as much debate. What killed these large beasts in a relative instant of geologic time?

A question asked less often: What happened when they disappeared?

A new study, based partly on dung fungus, provides some answers to both questions. The upshot: The landscape changed dramatically.

"As soon as herbivores drop off the landscape, we see different plant communities," said lead researcher Jacquelyn Gill of the University of Wisconsin, Madison, adding the result was an "ecosystem upheaval."

Gill and her colleagues found that once emptied of a diversity of large animals equaling or surpassing that of Africa's Serengeti, the landscape completely changed. Trees once kept in check by the mammoth gang popped up and so did wildfires sparked by the woody debris.

The results, which are detailed in the Nov. 20 issue of the journal Science, could paint a picture of what's to come if today's giant plant-eaters, such as elephants, disappear.

"We know some of these large animals are among the most threatened that we have on the landscape today and they have a lot of large habitat requirements and they eat a lot of food," Gill told LiveScience. "If these animals go extinct we can expect the landscape will respond."

Dung fungus

Gill and her colleagues analyzed sediment samples collected from Appleman Lake in Indiana as well as data from sites in New York.

They focused on a dung fungus called Sporormiella that must pass through a mammal's gut to complete its life cycle and reproduce via spores. More of such spores indicate more dung and more megafauna around to contribute to the fecal contents. Within that same sediment, the team looked at pollen and charcoal as proxies for vegetation and fires, respectively.

Sediment layers accumulate over time and can indicate when the stuff embedded in it was around. By matching up the dung spores along with vegetation and fire indicators in certain layers, the researchers figured the large herbivores were already declining before the vegetation started changing or wildfires took off.

The changes in spore abundance suggest the megafauna began to decline some time between 14,800 and 13,700 years ago. By 13,500 years ago, the decline was in full force, Gill said.

Rather than getting vaporized in an instant, the results suggest the animals gradually dwindled for about 1,000 years.

Here's how it may have gone down: The large herbivores started to decline. Without such leafy eaters to keep broad-leaved species in check, trees such as black ash and elm took over a landscape once dominated by conifers. Soon after, the accumulation of woody debris sparked an increase in wildfires, another key shaper of landscapes, the researchers say.

What killed the mammoths?

As for what drove the beasts into their graves, Gill says the findings don't put the nail in the coffin, but do rule out some ideas. To explain the extinction, scientists have put forth climate change, hunting by humans such as the Clovis people (known for using advanced spear tips), and even impact by a comet. The answer could be a combination of several factors, scientists say.

Gill says this new study is a strong one because all of the evidence comes from one place, and so the researchers aren't making comparisons across different regions whose sediments may be off in terms of timing.

If the timing is accurate, as Gill says it should be, the findings can rule out the idea of a meteor or comet killing off the creatures some 13,000 years ago.

And since the plant community didn't change until after the big guys began to decline, that's a mark against climate change. (A warming climate was considered the cause of a revamping of vegetation, and thus animal habitat.)

"At this site, we can say that habitat loss didn't cause the decline, because the major habitat shift happens after the collapse [of the megafauna]," Gill said. "And habitat change is a big line of argument in the climate camp. If climate change is causing these extinctions, you'll have to evoke another process than habitat loss."

Hunting, at least that by the Clovis people, can also be ruled out at the site.

"It seems as though the animals were already in decline by the time [Clovis] people adopted this tool kit," Gill said, referring to the advanced spear tips thought to be more efficient at taking down large prey than hunting instruments used by humans prior to the Clovis.

The new study was funded by the Wisconsin Alumni Research Foundation, the UW-Madison Center for Climatic Research in the Nelson Institute for Environmental Studies, and the National Science Foundation.

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