Aedes Mosquitoes Found at Record 2438 Metres in Nepal

Aedes aegypti and Aedes albopictus mosquitoes and their larvae have been found in Chandannath, Nepal, at 2438 metres above sea level. The town is one of the highest locations where these dengue-carrying species have been discovered. Previously, the mosquitoes had been observed only at elevations of up to 2100 metres.

The findings come as dengue has spread across most of Nepal, fuelled by climate change as well as increasing travel. At least six people died of dengue in Nepal in 2025. Around 9000 people were infected with the virus that year, and it has now reached 76 out of the country's 77 districts.

Dengue cases have recently been reported in the high-altitude region of Mustang, Nepal. Pokhara serves as the main gateway to Mustang. Experts note that around 90 per cent of people infected with dengue are asymptomatic, suggesting reported cases represent only a small fraction of actual infections.

The Nepal Health Research Council is working with the Institute of Tropical Medicine in Antwerp, Belgium, to examine larvae and adult mosquitoes for changes in colour or shape indicating insecticide resistance or adaptation to different altitudes. Sunita Baral, a PhD student at the Nepal Health Research Council, examines mosquitoes inside a rearing cage as part of this effort.

The council studies larvae and adult mosquito specimens from many habitats to learn about dengue-carrying mosquitoes across Nepal.

Ishan Gautam, associate professor and chief of the Natural History Museum at Tribhuvan University in Kathmandu, shows Aedes larvae to students during awareness campaigns. Tribhuvan University organises these campaigns in which local people are shown live Aedes mosquito larvae and taught about breeding habits and removing stagnant water. Mosquito nets are being encouraged around Chandannath.

In one home there, local resident Devi Kannya Katayata breastfeeds her son Nehan Budha under a net. Photographer Yuri Segalerba documented these scenes while exploring how dengue has spread to Nepal's Himalayan districts. Amchi Khedup Loden Gurung, a traditional Tibetan healer, prepares Sowa Rigpa medicines in a clinic in Jomsom, northern Nepal.

Segalerba had been investigating the spread of dengue into high-altitude areas in the Peruvian Andes when he learned of the situation in Nepal. "It turned out to be the clearest setting for that question: a millennia-old medical tradition with its own framework for understanding illness, suddenly facing a disease it had never encountered before," he says.

@NewScientist reported that Segalerba's photo essay The Ascent of Temperatures captures the intersection of climate change, traditional knowledge systems and a rapidly spreading disease.

Sheets drying in the courtyard of Pokhara Hospital appear in his images, underscoring the infrastructure at the edge of these high-altitude zones now confronting dengue.