Peru battles worst dengue outbreak as climate warms
The outbreak is a warning sign for countries in the tropics, where dengue fever and other insect-borne diseases are increasingly prevalent, as a rapidly changing climate brings more hot and humid weather, which offers ideal breeding conditions for mosquito hosts. At worst, dengue fever can cause high fevers, severe organ failure, and death. The number of reported cases has increased roughly tenfold, from around 500,000 in 2000 to 5.2 million in 2019, according to the World Health Organization, which declared in March that dengue was a “major public health problem ” for the Americas region.
The latest wave comes as northern regions of Peru saw record rainfall in March. “In terms of climate change, increased rainfall, higher temperatures and higher humidity all favor the mosquito,” Raman Velayudhan, who leads WHO’s Neglected Tropical Diseases programme, said during a briefing. a press conference in April.
The outbreak was exacerbated by the onset of the El Niño weather phenomenon, a regular event it starts with warm waters developing off the Pacific coast of South America and weakening trade winds causing water to flow towards the continent. This warming typically occurs every three to five years, before a period of cooler ocean waters and stronger winds known as La Niña.
Climate change has increased expected rainfall during Peru’s El Niño because more water evaporates into the air of a warmer ocean, which can then fall all at once when it reaches land, according to the U.S. Environmental Protection Agency, as opposed to less rain falling over a longer, more stable period of time.
Jason Mackenzie, professor of virology at the University of Melbourne’s Doherty Institute, said there is a clear link between increased rainfall and outbreaks of mosquito-borne diseases. “Increased rainfall leads to more accumulated water and so you get more mosquitoes laying eggs,” he said.
A study published last year by US and Peruvian public health experts in the journal PLOS Neglected Tropical Diseases found a “strong” link in Peru between dengue fever outbreaks, warmer weather and the El Niño Southern Oscillation.
“Dengue fever cases have increased dramatically over the past four decades, primarily due to anthropogenic factors, including climate change,” the authors wrote, adding that “climate change is expected to increase the frequency of El Niño events.”
Peru has also banned storing plain water in open containers, while rushing to open a field hospital in one of its hardest-hit regions. Residents were also banned from trying to treat suspected dengue fever cases at home and instead told to go to clinics.
“Dengue kills,” Health Minister Rosa Gutiérrez Palomino said in a statement Tuesday. “Because of this, help me eliminate mosquito breeding sites.”
Mackenzie, the Australian professor, said there had been several instances of increased rainfall leading to outbreaks of mosquito-borne diseases in places where they were not known to spread. Japanese encephalitis emerged 2,000 miles further south than ever – reaching Australia – after record flooding in mostly cool, dry areas last year.
West Nile virus also often resurfaces in the United States after an explosion in mosquito breeding activity during a wet period, followed by a dry period that pushes mosquitoes into urban areas in search of water, Mackenzie said.
washingtonpost
