Why is dengue surging in Nepal?

Long considered a tropical disease, Dengue is now endemic across Nepal, as data shows.

Climate change stands as a key factor.

“At high elevations in Nepal, there is high confidence that climate change has driven the expansion of vector-borne diseases (VBDs) that infect humans”, said the Intergovernmental Panel on Climate Change (IPCC) sixth assessment report, noting that viruses like dengue, chikungunya, and Japanese encephalitis are also emerging in Nepal’s hilly and mountainous areas.

A study by the Nepal Health Research Council (NHRC) in 2019 also notes that there is increasing evidence about the impacts of climate change on vector-borne diseases including dengue fever with vectors now found in high mountains with over 2,000 m above sea level, which were previously non-endemic areas.

Usually, higher temperatures combined with precipitation favour Aedes mosquitos to create new suitable habitats where larval development hastens; increasing adult populations. 

While climate change has driven the expansion to more territories, the government’s apathy (all three tiers) towards the possibility of the epidemic is behind its intensity. 

In 2021, the federal government launched the “National Adaptation Plan 2021-2050” earmarking a total budget of $500 million to strengthen surveillance systems with emergency preparedness and response to climate-sensitive diseases by 2030. However, stats on the dengue endemic suggest otherwise about the plan’s effectiveness. 

Last year, public health experts forewarned the possibility of dengue resurgence in 2023 but the concerned authorities didn’t heed.

Local authorities are expected to play a crucial role in controlling any outbreak. Local authorities in coordination with health authorities must have taken proactive initiatives such as surveillance and disposal of breeding sites, early spraying of insecticides, public awareness initiatives, and other effective control initiatives to destroy the eggs of infected mosquitoes.

However, this wasn’t the case. Many experts argue the public health response to the disease prevention and control mechanisms commenced belatedly when the outbreak had already surged.

Reportedly, only six out of 18 local governments from the three districts of Kathmandu Valley attended a meeting called on by the Ministry of Health and Population (MoHP) in early July to discuss the dengue risk. 

“We did not learn the lessons of 2019, and we haven’t learned the lessons of 2022,” wrote Sonia Awale from The Nepali Times while reporting the possibility of a dengue outbreak this monsoon. 

The present urban environment which comes with structural ills and creates favourable conditions for the vector spread is another contributing factor to the surging spread of viruses in urban regions.

Growing population pressure against poorly planned and inadequate infrastructure such as inefficacy in waste management, poor drainage system, haphazard physical construction, and poorly managed roads, streets, and public spaces (proliferated with puddles) have collectively aggravated the urban environment — contributing to a breeding ground for not only vector diseases but also water-borne diseases and their rapid spread.

Why should Nepal worry?

Given Nepal’s frail public health infrastructure and resources, and weak response-ability, outbreaks can quickly take disastrous turns. For instance, the dengue casualty figure stood at 88 last year. The same year the Kathmandu valley faced acute blood shortage — grappling with the mounting need for platelet-rich plasma — after dengue cases spiked.

While dengue can spread throughout the year, the transmission usually peaks during the post-monsoon period as stagnant rainwater provides a favourable breeding ground for female mosquitoes to lay their eggs in warm and humid climates providing the right conditions.

Last year, the transmission surged during the months of August and September post-monsoon. This year, over 7,000 cases have already been reported by mid-July while the rainfall has only begun. 

Dr. Sher Bahadur Pun, Coordinator of the Research Unit at Sukraraj Tropical and Infectious Disease Hospital, emphasised, “It should be noted that the current outbreak is just the beginning and is expected to continue for several weeks and or even months.”

With an alarmingly high disease burden, the disease can badly impact Nepal’s socio-economic landscape which is already in poor conditions at the moment.

According to estimates, dengue costs the global economy USD 8.9 billion a year. About 40% of the estimate accounted for productivity costs — expenses from both paid and unpaid work that results from illness, treatment, and premature death.