Drug-Resistant Malaria Spread Across Southeast Asia

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A new study discovered that multidrug-resistant forms of malaria parasites are rapidly spreading across Southeast Asia, leading to “alarmingly high” treatment failure rates of widely used frontline medication. Furthermore, researchers fear that the parasites may travel across to other regions.

In a study published in The Lancet Infectious Diseases Journal revealed that the parasites have moved from Cambodia to Laos, Thailand, and Vietnam, where first-choice drugs are not curing half of the patients. Additionally, the study noted that 80% of the most prevalent malaria parasite were now resistant to the two most common anti-malarial drugs.

The Plasmodium falciparum parasites have also acquired resistance linked to the failure of treatment in half of the cases to one of the newest and most potent frontline drug combinations, they said.

There are about 219 million cases of malaria around the world each year. The disease kills about 435,000 people every year – most of them are children under the age of five.

Symptoms include cycles of feeling cold and shivering followed by high temperature with severe sweating. Without treatment, the parasite can lead to breathing problems and organ failure.

The US Centers for Disease Control and Prevention told in a 2018 report that the development of resistance to drugs poses one of the greatest threats to malaria control and results in increased malaria morbidity and mortality.

Furthermore, resistance to currently available antimalarial drugs has been confirmed in only two of the four human malaria parasite species, Plasmodium falciparum, and P. vivax. While the agency also noted that it is unknown if P. malariae or P. ovale has developed resistance to any antimalarial drugs. 

P. knowlesi, zoonotic monkey malaria that infects humans in forest fringe areas of Southeast Asia, is fully susceptible to chloroquine and other currently used drugs.

Initially, malaria was treated with a combination of two drugs – artemisinin and piperaquine, which was introduced in Cambodia in 2008.

By 2013, the first cases of the parasite mutating and developing resistance to both drugs were detected, in western parts of the country.

The latest study analyzed blood samples from patients across South East Asia to inspect the parasite’s DNA showed resistance had spread across Cambodia and was also in Laos, Thailand, and Vietnam.

It had also picked up further mutations, making it even more problematic.

Though the study showed that malaria parasites had developed resistance to the two primary drugs used to combat its symptoms, there are alternative drugs that can be used instead.

“With the spread and intensification of resistance, our findings highlight the urgent need to adopt alternative first-line treatments,” Prof Tran Tinh Hien, from the Oxford University Clinical Research Unit, in Vietnam, said.

That could include using different drugs alongside artemisinin or using a combination of three drugs to overcome resistance.

However, what researchers fear more is that the findings raise the “terrifying prospect” that drug-resistance could spread to Africa, where more than nine in 10 cases of the disease are.

“This highly successful resistant parasite strain is capable of invading new territories and acquiring new genetic properties, raising the terrifying prospect that it could spread to Africa, where most malaria cases occur, as resistance to chloroquine did in the 1980s, contributing to millions of deaths,” Prof Olivo Miotto, from the Wellcome Sanger Institute and University of Oxford, said.

Specifically, researchers are wary of the fact that drug-resistant malaria would yield similar results as P. falciparum, a malaria strain that has developed resistance to nearly all of the other currently available antimalarial drugs, such as sulfadoxine/pyrimethamine, mefloquine, halofantrine, and quinine. 

Chloroquine-resistant P. falciparum first developed independently in three to four areas in Southeast Asia, Oceania, and South America in the late 1950s and early 1960s. Since then, chloroquine resistance has spread to nearly all areas of the world where falciparum malaria is transmitted.

More than 200 million people are infected with the P falciparum parasite, which is responsible for nine out of ten malaria deaths globally.

Despite the current news, researchers say that this is not something that people should panic or worry about.

“These parasites are scary beasts, there’s no doubt,” Prof Colin Sutherland, from the London School of Hygiene and Tropical Medicine, said.

“However, I wonder if these parasites are not very fit because the population as a whole is crashing.”

Notably, the number of cases in Cambodia was 262,000 in 2008 and dropped to 36,900 cases in 2018.

“The implications are not as severe as we might think,” Sutherland said. Furthermore, he added the even though drug-resistant malaria has spread; it’s unlike for it to be considered as a global health threat.

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