Asia Nears Malaria Elimination, but Climate Change Threatens Hard-Won Gains

PHNOM PENH/VIENTIANE — After decades of progress, malaria is retreating across much of Asia. Cambodia, Laos and Vietnam are now within reach of eliminating the disease, while cases across the Greater Mekong Subregion have fallen by 67 percent since 2010.

But just as Cambodia, Laos and Vietnam edge closer to malaria-free status, health experts are warning that climate change could complicate the final push.

Extreme weather events, rising temperatures and shifting rainfall patterns are creating conditions that could increase the risk of mosquito-borne diseases, including malaria and dengue, in parts of Asia.

“As you know, extreme weather events are a big problem in Bangladesh. Floods, cyclones and heat waves are very common in our country,” said Dr. Md. Mushfiqur Rahman, advisor to Bangladesh’s National Malaria Elimination Program.

“There is also an increased risk of disease, like malaria and dengue, associated with this climate risk.”

Bangladesh is among the countries closely watching how climate change may affect malaria transmission. While scientists are still studying the relationship, Rahman said the mosquitoes that carry malaria and [also] dengue are highly sensitive to weather conditions.

“We don’t know for sure whether the increase in vector-borne diseases in our country is caused by climate change, but we do know that the vectors responsible for the development of malaria and [also] dengue are climate-sensitive,” he said.

Temperature and humidity affect both the lifespan of mosquitoes and the development of the parasites they carry. According to Rahman, the optimal temperature for parasite development [in mosquitoes carrying malaria] is between 15 and 35 degrees Celsius.

“That means as temperatures increase, so do the number of cases,” he said.

For countries that have spent years driving down malaria infections, those trends present a new challenge. Warmer temperatures can expand mosquito habitats, lengthen transmission seasons and increase the risk of outbreaks in places where cases have become rare.

Those concerns formed part of discussions at the 10th Asia Pacific Leaders’ Summit on Malaria Elimination in Vientiane on June 5, where ministers and senior officials renewed their commitment to eliminating malaria across the Greater Mekong Subregion by 2030.

Hosted by the government of Laos and the Asia Pacific Leaders Malaria Alliance (APLMA), the summit brought together representatives from Cambodia, Laos, Myanmar, Thailand and Vietnam, along with international partners, to discuss how to sustain momentum during what many described as the “last mile” of malaria elimination.

Malaria cases across the Greater Mekong Subregion have fallen by 67 percent over the past 15 years, according to figures presented at the summit. Officials attributed the decline to stronger surveillance systems, wider access to diagnosis and treatment, and years of cooperation between neighboring countries.

“I am proud to reaffirm Lao PDR’s commitment to achieving our national malaria elimination goal by 2030,” Lao Prime Minister Sonexay Siphandone told delegates, while acknowledging that challenges remain.

Cambodia, Laos and Vietnam are now among the countries closest to eliminating malaria. Annual case numbers have fallen to the low hundreds, bringing malaria-free certification within reach.

To earn World Health Organization certification, countries must record three consecutive years with no indigenous malaria transmission. The challenge now is ensuring that malaria does not return once local transmission reaches zero.

“We are proud of the progress our country has made, and we are under no illusion that the work is completed,” Lao Health Minister Baykham Khattiya said.

Elsewhere, malaria remains harder to eliminate.

Myanmar and Thailand continue to face persistent transmission, particularly in border regions where populations are highly mobile and access to healthcare is often limited. Reaching migrant workers, forest communities and people living in remote areas remains one of the biggest obstacles.

“The progress made in the Greater Mekong Subregion is significant — but it remains fragile,” said Dr. Sarthak Das, Chief Executive Officer of APLMA.

“With elimination now in sight, this is the moment to sustain political commitment, strengthen domestic financing and invest in the systems needed not only to stop transmission, but to prevent malaria from returning.”

Funding is also a concern.

As malaria cases decline, governments and donors may be tempted to shift resources elsewhere. Yet experts warn that the final stages of elimination are often the most difficult and expensive, requiring health workers to track infections in remote communities and respond rapidly when new cases emerge.

The summit’s Joint Call to Action urged governments to maintain domestic financing, strengthen regional cooperation and protect gains achieved over the past decade. It also recognized that countries face different challenges on the road to elimination.

What works in Cambodia may not work in Myanmar, where conflict, displacement and insecurity continue to complicate malaria control efforts. Likewise, countries making progress toward elimination must now contend with a changing climate that could alter where and how the disease spreads.

The region has already shown that malaria can be pushed back. The challenge now is ensuring it stays that way. As countries close in on elimination, climate change, cross-border transmission and funding pressures threaten to complicate the final steps toward a malaria-free Asia.