Scientists issue warning about potential surge in disease carried by mosquitoes: 'Can help public health authorities prepare'

The findings of a study published this September in the journal PLOS Neglected Tropical Diseases indicate that factors including rising global temperatures and changing rainfall are set to increase the risk of mosquito-borne diseases in Brazil — and that effective mitigation of those factors could help.

What's happening?

Researchers from Australia's Burnet Institute have studied the impacts that rising temperatures, heavy rains, and human activity may be having on Brazil's mosquito populations. As summarized by PLOS, the scientists developed a new mathematical model to combine climate, urbanization, and biological factors for more comprehensive projections.

They found that, by 2080, mosquito density is set to increase if current weather patterns continue, especially in South and Southeast Brazil. Warmer, wetter habitats, conducive to mosquito breeding, are also projected to result in higher transmission rates of illnesses spread through mosquito bites, such as dengue fever, which is already seeing an uptick in the region.

"Brazil already carries one of the world's highest burdens of mosquito-borne disease, and our results show these pressures could grow in the coming decades," the co-authors said, per PLOS. 

"The difference between a high- and low-emissions future is stark: Strong climate action could cut Brazil's projected mosquito density increases by two-thirds."

Why is this concerning?

Arboviruses, which are transmitted to humans and animals through bites from mosquitoes and similar insects, can pose a range of problems. Dengue, Zika, chikungunya, and West Nile virus can each complicate pregnancies, for instance. Any fever increases prenatal risks, and Zika and chikungunya are both linked to the potential for birth defects.

These are just a couple of examples of the consequences of disease spread. Disability, chronic illness, health system strain, lost wages, and other economic impacts are potential outcomes as well, and all may pose greater impacts in low- and middle-income countries, like Brazil.

Meanwhile, cases of West Nile virus have also been rising this year in the United States, where warmer, wetter weather patterns may be a contributing factor. 

A recent study from the University of Cincinnati has also shown that mosquitoes may consume more blood in order to survive extended periods of drought — another consequence of rising global temperatures.

What can be done?

The co-authors emphasized that their findings could be used to improve public health efforts, such as those related to infection monitoring, prevention, and treatment. 

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"By showing where and when mosquito risks are likely to be greatest, our study can help public health authorities prepare and respond more effectively," they wrote in their paper. The likelihood that transmission rates could increase means that ministries of health may want to strengthen capacity for effectively handling arboviruses.

The co-authors also said their study "highlights the importance of climate action to reduce future health risks." 

If rising global temperatures and the intensifying weather conditions they fuel can be mitigated, future disease burden could go down. This could make a big difference, particularly in low- and middle-income countries, where health systems already disproportionately impacted by climate-related medical concerns — such as water contamination, food shortages, and extreme heat exposure — could experience some relief.

It also means that there's a role for everyone to play, from global health organizations to country medical systems, clean energy advocates, and more. Even at the individual level, making shifts away from dirty energy sources — oil, coal, and gas — can reduce the generation of heat-trapping pollution. Installing solar panels, switching to an electric vehicle, using public transit, and carpooling are all steps that can help mitigate rising temperatures.

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