Climate change raises dengue risk

PETALING JAYA: Half of the world’s seven billion people will be at risk of getting dengue if minimum temperatures in certain regions continue to rise, warned the first ever global mapping report on dengue vulnerability.

According to Mapping Global Vulnerability to Dengue using the Water Associated Disease Index, while South-East Asia and South Asia already faced the highest levels of vulnerability to dengue, western and central Africa, as well as parts of Europe and the mountainous regions of South America would be affected if minimum temperatures there continue to rise.

“The increase due to climate change alone would more than double the number of those at risk to an estimated 3.5 billion,” said the report published by the United Nations University’s Canadian-based Institute for Water, Environment and Health (Unu-Inweh) on the university’s website yesterday.

Vulnerability in this case is determined by exposure and susceptibility, the latter influenced by access to healthcare, clean water, decent housing, dengue control measures and government policies.

Aedes mosquito eggs are rendered non-viable at temperatures below -2°C. But should minimum temperatures rise by a few degrees, the eggs could survive, putting large populations at risk of exposure to the mosquito.

While the authors noted that a rise in temperatures could make the environment too hot for mosquitoes in some places, overall warmer climates were expected to facilitate the spread of dengue both northwards and southwards of the equator.

The report also noted that Brazil reported the largest number of dengue cases – about 450,000 from 2004 to 2010.

It also listed Indonesia, Vietnam, Mexico, Venezuela, Thailand, the Philippines, Colombia, Malaysia and Honduras as among the top 10 countries where dengue is endemic.

“Climate change is increasing dengue vulnerability in some regions and there is a pressing need for improved waste management and sanitation in urban areas as part of a wider public health response,” said Dr Anthony Capon, director of Unu’s Malaysia-based International Institute for Global Health at the UKM Medical Centre in Kuala Lumpur.

Close to 400 million people today are infected by the virus, causing between 250,000 and 500,000 severe cases annually and some 20,000 deaths.