From VOA Learning English, this is the Health and Lifestyle Report.

A new study finds that the most widely used anti-malarial treatment might not help children and pregnant women as much as other patients.

The pregnant women and children studied had lower amounts of one of the treatment drugs than non-pregnant adults.

The most common drugs to treat malaria are a combination of artemether and lumefantrine. Together the combination therapy is also called ACT. This research may explain why usual doses of ACT, sometimes fail to cure. The research also suggests that a change in the treatment program may help to cure more people and prevent resistance.

But other experts say this study alone is not enough to change treatment recommendations.

Treatment failures

Since 2000, cases of malaria around the world have dropped by 60 percent. The decrease is credited to billions of dollars-worth of programs to prevent and treat the disease.

However, in some parts of the world, malaria is still a serious problem.

"More than 400,000 people are killed every year by malaria. And, actually, most of them are small children under 5 years of age in sub-Saharan regions of Africa."

That is Frank Kloprogge. He is a researcher working with the WorldWide Antimalarial Resistance Network. He co-wrote the new study.

He and other researchers examined 31 studies involving more than 4,000 people. They looked at amounts of lumefantrine in patients' blood seven days after treatment began. They found that children and pregnant women had lower-than-average amounts.

"Pregnant women were, for example, 20 percent lower. And depending on the body weight group in children, it was somewhere between 15 and 25 percent lower."

Pregnant women and children seem to absorb and use medicines differently.

Kloprogge explains that children have different levels of important enzymes. And pregnant women, he adds, have different amounts of water and fat. These can all affect how a drug works in the body.

"Pregnant women also have changes in body composition. You can think about water and fat content. And this also has an impact on how the drug distributes through the body."

Some studies have found that children and pregnant women are more likely than others to develop malaria again within weeks of treatment. Kloprogge says that failing to treat malaria is not the only concern. When malaria survives exposure to low amounts of anti-malarial drugs, it can change into a new strain of malaria. And that strain is resistant to anti-malarial drugs.

The researchers offer a different treatment model based on their findings. They suggest that taking the pills for five days would be more effective than the current three-day schedule.

Andrea Bosman leads a malaria prevention and treatment department at the World Health Organization. He praises the study as well-done and important.

But, he warns, this model is based on a study and not on medical trials. He says the WHO does not generally make recommendations based on modeling studies.

"It is still a modeling study, and we do not generally make recommendations based on modeling studies alone. We require clinical data."

He says longer treatment carries its own risk. He says the longer the treatment goes on, the less likely people are to continue it. Not completing a drug treatment can also add to the likelihood of resistance.

Other studies have not found that a change in treatment plan is necessary. Kloprogge and his team are seeking support for a medical trial of the five-day treatment schedule.

I'm Anna Matteo.

Steve Baragona reported this story for VOA News. Anna Matteo adapted it for Learning English. Caty Weaver was the editor.

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recommend – v. to suggest that someone do (something) : recommendation – n.

dose – n. the measured quantity of a therapeutic agent to be taken at one time

absorb – v. to take in (something, such as a liquid) in a natural or gradual way : often used as (be) absorbed

enzyme – n. a chemical substance in animals and plants that helps to cause natural processes (such as digestion)

composition – n. the way in which something is put together or arranged

impact – n. a powerful or major influence or effect

distribute – v. to give out to or deliver to

exposure – n. the fact or condition of being affected by something or experiencing something : the condition of being exposed to something

strain – n. a group of closely related living things that look similar but possess one or more unique characteristics

model – n. a set of ideas and numbers that describe the past, present, or future state of something (such as an economy or a business)

clinical – adj. always used before a noun : relating to or based on work done with real patients : of or relating to the medical treatment that is given to patients in hospitals, clinics, etc.