Health authorities thought they had almost got rid of it, but it has slowly resurfaced.
Nepal is concerned about a resurgence of dengue fever in its territory, a consequence of climate change and urbanization.
The statistics are eloquent. In 2004, the Himalayan country had recorded only four cases of this virus which causes high fevers which are sometimes fatal.
Since the beginning of this year, more than 28,000 people have already been infected, 12 have died. And doctors believe that these figures are probably underestimated.
It is a fact that dengue fever mosquitoes have started to invade the high Nepalese valleys.
Around twenty cases have been reported in the Solukhumbu district, home to the world's highest peak, Mount Everest.
“There shouldn’t be any,” said local health official Suman Tiwari. “The most surprising thing is that even people who have never travelled have tested positive.”
More than 4,000 cases of dengue fever have also been reported in the capital Kathmandu alone, which is located at an altitude of 1,400 metres.
"Unfortunately, it is moving geographically," confirms Dr Sher Bahadur Pun of Sukraraj Hospital. "It was previously seen only in certain regions, it is climbing up the mountains and foothills of the Himalayas."
In some districts, hospitals are now overflowing with dengue patients.
“The number of cases is increasing exponentially,” Dr. Pun said. “With every outbreak, the number of people infected increases and I see more deaths.”
A global trend, according to the World Health Organization (WHO), which recorded over 7,900 deaths and 12.3 million confirmed or reported cases in the first eight months of this year. Double the number of the entire previous year.
Epidemiologists believe the spread of the disease is caused by changes in temperature and precipitation patterns, which allow Aedes aegypti mosquitoes to survive and breed at higher altitudes.
– “Annual” epidemics –
Nepalese virologist Narayan Gyawali also highlights the impact of urbanization and increased mobility of the population.
"Microclimates are created when an area is urbanized, the temperature and humidity increase," he notes, "it is an environment favorable to survival and reproduction."
In Nepal, the epidemic has been steadily progressing for three years. It peaked in 2022, with nearly 55,000 cases, including 88 deaths.
"Dengue was more of a cyclical disease. Now it comes back every year. We have to prepare to fight it annually," insists Gokarna Dahal of Nepal's Ministry of Health.
An "unfair" situation, he adds, noting that his country's responsibility for global warming is minimal but that Nepal is among those most affected.
While the responsibility for ensuring the health protection of the population lies with the Nepalese state, adds Meenakshi Ganguly of the NGO Human Rights Watch (HRW), those primarily responsible for climate change must play their part.
"Countries that emit the most greenhouse gases must do much more to protect people in countries like Nepal from the consequences of global warming," she said.
"Combating mosquito-borne diseases like dengue, which are spreading rapidly to new areas, must be part of this effort," insists Meenakshi Ganguly.
Dengue fever is already endemic in more than 130 countries worldwide, according to the WHO.
The UN organization has launched a global plan to coordinate the fight against the virus, for which it has requested a budget of 55 million dollars (50 million euros) for 2025.
Some four billion people worldwide — half the world's population — are at risk of contracting dengue fever and other arboviruses, including chikungunya and Zika, the WHO has warned. That number is expected to rise to five billion by 2050.
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