The upshot of global warming: lower dengue risk

Australian health researchers have predicted that the transmission of dengue could decrease in a future warmer climate, countering previous projections that climate change would cause the potentially lethal virus to spread more easily.

Writing in the journal Epidemiology and Infection, the scientists detailed how they used a mechanistic virus transmission model to determine whether climate warming would change dengue transmission in Australia. Using two climate models each with two carbon emission scenarios, they calculated future dengue epidemic potential for the period 2046–2064.

“There is significant concern in countries on the margin of the tropical areas where dengue is mainly found that, with global warming, dengue and other mosquito-borne viruses such as Zika will encroach and become common,” said co-lead researcher Associate Professor David Harley from The Australian National University (ANU).

But while previous studies have used correlative models to show increased dengue transmission under climate warming, Dr Harley’s mathematical model found that dengue risk might decrease in the wet tropics of north-east Australia under a high-emissions scenario, apparently due to mosquito breeding sites becoming drier and less favourable to the insects’ survival.

“Dengue epidemiology is determined by a complex interplay between climatic, human host, and pathogen factors,” the study authors wrote. “It is therefore naive to assume a simple relationship between climate and incidence, and incorrect to state that climate warming will uniformly increase dengue transmission.”

However, said Associate Professor Harley, “While we could see some reduction in dengue in Far North Queensland in a future warmer climate, the disease is widespread elsewhere in the world where outcomes would be different.

“Generally, health and other impacts of climate warming will be negative in Australia and elsewhere in the world,” he said.