The Grapevine

Dengue Fever: Millions Of Potential Cases Avoidable By Reducing Global Temperatures

By using computer models, researchers determined that millions of people could avoid dengue fever by coordinating efforts to cap global warming at 1.5 degrees Celsius (or 2.7 degrees Fahrenheit.) 

The study titled “Limiting global-mean temperature increase to 1.5–2 °C could reduce the incidence and spatial spread of dengue fever in Latin America” was published in the Proceedings of the National Academy of Sciences on May 29.

Maintaining global temperature is the long-term goal of the Paris Climate Accord, the agreement between world leaders to keep temperatures under 2 degrees Celsius above pre-industrial levels. The aim is to limit the rise to 1.5 degrees Celsius, which many believe to be approaching soon. 

“There is growing concern about the potential impacts of climate change on human health,” said lead author Felipe Colón-González from the University of East Anglia, England. “This is the first study to show that reductions in warming from 2 degrees Celsius to 1.5 degrees Celsius could have important health benefits.”

Dengue fever is a disease transmitted by mosquitoes, often occurring in tropical and subtropical regions of the world. The virus is carried and spread by Aedes mosquitoes, which thrives in warmer climates.

Treatment involves relieving symptoms as there is no specific medicine or antibiotic to target the infection. Severe dengue is a deadly, hemorrhagic form of the infection which is one of the leading causes of hospitalization and death in Asian and Latin American countries.

The incidence of dengue has increased 30-fold over the past fifty years. Research suggested temperature is an important factor that influences mosquito biting rate, egg development, survival of the mosquito, etc. For instance, nearly 80 percent of severe dengue cases from 1983 to 2001 in Thailand occurred when the temperature was 27 to 29.5 degrees Celsius (approx. 82.4 degrees Fahrenheit) and when humidity was greater than 75 percent.

The research team studied clinical dengue reports from Latin America and predicted the impact of various climate scenarios using computer models. 

By limiting global warming to 2 degrees Celsius, the findings revealed a reduction in annual dengue cases by up to 2.8 million cases per year in Latin America and the Caribbean. Additionally, half a million cases could further be avoided by limiting warming to 1.5 degrees Celsius.

The study found Southern Mexico, the Caribbean, northern Ecuador, Colombia, Venezuela and coastal Brazil will be affected the most by increases in dengue cases.

“Understanding and quantifying the impacts of warming on human health is crucial for public health preparedness and response,” said co-author Dr. Iain Lake, also from the University of East Anglia.

“Warming has already reached 1 degree Celsius above pre-industrial levels, and the current trajectory, if countries meet their international pledges to reduce CO2, is around 3 degrees Celsius — so clearly a lot more needs to be done to reduce CO2 and quickly if we are to avoid these impacts.”