October 10, 2017

News Media, Travel, and Drug-Resistant Malaria

Since news of the arrival of “super malaria” in Vietnam, media reports have claimed that the malaria parasite causing “super malaria” cannot be killed by current antimalarial treatments. This is untrue; the WHO released a report on Sept. 29 detailing the medications available to treat this particular malaria strain.

Multidrug resistance will likely influence the choices a travel health provider will offer when recommending chemoprophylaxis (malaria prevention drugs) to individuals operating in these areas. Risk of malaria infection is present year-round in Cambodia, Laos, Thailand, and Vietnam and is highest during and immediately following the rainy season, which typically occurs June to November. Regardless of season, ongoing transmission of drug-resistant malaria highlights the importance of constant use of mosquito bite prevention measures, as well as consistently taking malaria prevention medication as prescribed.

Malaria in the Greater Mekong

Map of super malaria outbreak

The Greater Mekong subregion has reported antimalarial drug resistance since the 1950s, when malaria parasites first became resistant to the medication chloroquine. Since that time, artemisinin-based drugs were the first-line treatment for malaria infections. However, malaria treatment failure rates have been increasing in multiple areas of the Greater Mekong since 2008, indicating a strain of the malaria parasite was gaining resistance to the drug. Since then, scientists have identified mosquitoes carrying the resistant malaria strain in select provinces of Cambodia, Thailand, Laos, and Vietnam (map). During this time, as malaria was transmitted by mosquitoes between these countries, many with different first-line treatments for malaria, the malaria strain acquired resistance to the drug piperaquine.

Mosquitoes carrying artemisinin-resistant malaria parasites have also been reported in Kayim Province, Myanmar, over 800km (approximately 500 miles) west of the Cambodia. These parasites show only distant genetic relatedness to the multidrug-resistant strain of malaria reported in Cambodia, Laos, Thailand, and Vietnam. Officials have not reported any additional spread of the strain in Kayim Province, Myanmar.

That this multidrug-resistant strain has not spread beyond these countries since 2008 suggests either the local mosquito subspecies are less competent malaria vectors, or that malaria parasite’s mutations may also make it less able to survive inside their mosquito vectors before being transmitted to human hosts.

We recommend all individuals consult their travel health provider well in advance of a trip to the Greater Mekong subregion to determine which antimalarial drugs are best suited to each person. In addition, individuals should follow insect bite precautions at all time.