Dengue, a mosquito-borne illness, used to plague the tropical Terai plains. However, it has trespassed into hilly regions, causing concern and becoming a nationwide crisis in recent years.
A visitor who had contracted dengue overseas reported the disease’s first transmission in the country in 2004. A second minor outbreak followed in 2006, which reached a total of 32 cases.
In 2010 and 2013, two other minor outbreaks occurred, respectively, with most cases concentrated in the Terai region. By the end of the first decade, dengue was no longer an occasional outbreak but rather a perennial low-level condition, especially in the lowlands.
The frequency and severity of outbreaks grew both in 2016 and 2017, a shift in transmission patterns. In 2019, a crisis emerged with 17,992 cases and six deaths reported across 68 districts, significantly impacting Bagmati Province. Outbreaks have recurred every three years since.
In 2022, the nation faced its worst outbreak, with nearly 55,000 cases and 88 deaths. Despite a lower caseload, 2023 remained a high-risk year with continuing risks for subsequent years. In 2024, around 34,000 dengue cases were reported, including cases in Solukhumbu, the Mount Everest district. As of July 2025, more than 1,500 cases have been recorded nationwide, but the real number is likely higher since many people treat dengue at home or go untested.
And it could escalate further, with health officials warning of over 60,000 infections in the next three months without immediate action.
The rise in dengue cases is no accident. Climate change and urbanisation are major contributing factors. Warmer temperatures, shifting rainfall patterns, and increased urban sprawl have created ideal breeding grounds for Aedes aegypti, the mosquito responsible for transmitting dengue.
“Dengue should not exist in high-altitude regions like Solukhumbu,” says Suman Tiwari, the district health chief. “Yet, we’re seeing cases among people with no travel history, proving how far the disease has spread.”
According to a report by GAVI, the nation’s average temperature has risen by about 1.3°C since the 1970s. This seemingly small shift has expanded the habitat range for dengue-carrying mosquitoes, allowing them to thrive at altitudes that were once too cold for survival.
A recent preprint study published on MedRxiv found that changing climate patterns have turned Nepal into an increasingly suitable environment for dengue vectors. The higher elevations, once considered dengue-safe zones, are now at risk due to shifting ecological conditions. Despite emitting a minimal carbon footprint, the country acutely feels the disproportionate effects of climate change.
And, with all the chaos looming, the healthcare system is no better. Hospitals do prepare themselves for this wave of diseases each year with rapid diagnostic kits, stocked medicines, and extensive training for medical staff. But is that enough for the outbreak?
Dr Sher Bahadur Pun, an infectious disease expert at Sukraraj Tropical and Infectious Disease Hospital (STIDH) in Kathmandu, mentions that the number of patients typically ranges from 70 to 100, but during the outbreak, the numbers increase to 1,000 per day.
Despite the availability of the resources, it’s extremely challenging to manage nearly 10 times the capacity of the institution. Consequently, doctors and nurses began offering outpatient services outdoors.
On a positive note, authorities launched a nationwide dengue “Search and Destroy” campaign, guided by WHO Nepal. Over 100 trained youth volunteers are visiting neighbourhoods, armed with gloves, buckets, and loudspeakers, as they actively eliminate mosquito breeding sites like stagnant water and discarded tyres.
But the challenge is steep. In hard-hit cities such as Kathmandu, Biratnagar, and Pokhara, construction sites and blocked drains have overwhelmed local systems. The dense population also makes it easier for mosquitoes to thrive.
Meanwhile, rural communities struggle with inadequate sanitation infrastructure. Combating dengue takes more than just medical intervention; it demands a societal shift in handling waste, water, and climate adaptation.
The dengue outbreak is a wake-up call to recognise the deep link between public health and climate. And countries most responsible for climate change must acknowledge their role and act with urgency.
Pratiksya Bhatta is a junior editor with Nepal Connect.