Unprecedented rainfall may have impacted Nepal’s most devastating Dengue epidemic in years

People | Human Health

By Isabel Rowbotham, Co-Editor in Chief

Published May 27th, 2023

After the unprecedented rainfall and flooding across South Asia in 2022, Nepal, a climate-vulnerable nation, experienced a devastating dengue epidemic. Similar to a ticking bomb, the mosquitoes were ready to breed in the warm and humid conditions of Nepal’s monsoon season.

Dengue is a mosquito-borne disease, which according to the WHO, has increased eightfold in incidence worldwide in the last decades. The vast majority (70%) of the global burden of dengue is in Asia, but the disease was first reported in Nepal in 2004.

An aerial view of Kathmandu, Nepal. | Michael Parfitt

In 2022, Nepal reported the worst dengue epidemic in years. Compared to its last outbreak in 2019, the 2022 epidemic was devastating. Nepal confirmed 42,504 cases, 55% of these being in the densely populated capital Kathmandu, and 51 deaths despite dengue fatality being rare.

Lack of sustainable waste management, overflowing landfills and a wet monsoon season all feed into the ideal breeding ground for mosquitoes (Aiede aegypti). Thus, the unprecedented heavy rainfall in 2022 caused the local dengue outbreak in Kathmandu a lot earlier in the year than usual.

‘Nepal confirmed 42,504 cases, 55% of these being in the capital, the densely populated capital Kathmandu.’

Despite Nepal’s low greenhouse gas contributions, it is globally vulnerable to climate change. All factors affected by climate-related temperature, rainfall and humidity changes play a role in determining the habitat and distribution of many species. Nepal has a wide variety of climate zones, ranging from the frigid mountain summits of the Himalayas to the tropical southern lowlands.

Temperatures of the Nepalese monsoon-summer season are rising 0.03°C per year and 0.05°C per year, respectively. Rainfall is plentiful from June to early October, with future climate projections expecting monsoon precipitation to be on the rise.

As global temperatures increase, countries are at risk of dengue and mosquitoes associated with vector-borne diseases; some have called this an early warning for the whole of southern Asia. In 2022, a rapid rise in cases was seen in India, Nepal, Bangladesh and Pakistan simultaneously. The outbreak was attributed to rainfall and flooding.

Excess rainwater in streets and households is the main reservoir for mosquito breeding. | Michael Parfitt

Climate change has also impacted Nepal’s migration patterns. The increased precipitation has caused many people to abandon agriculture-based livelihoods and search for work in busy cities. Current migration trends even point to the abandonment of farming in the next 30 years.

Nepal struggles with rapidly increasing urbanisation, internal migration, and poor water and waste management. Although, the largest culprit for the deadly dengue outbreak can likely be rooted in the country’s debilitated health system, lack of accessible facilities and weak epidemiological surveillance. It was additionally reported that dengue epidemic monitoring may have been affected by the COVID-19 pandemic.

‘Some have called this an early warning for the whole of southern Asia.’

Dengue is not the only concern for public health across Asia. According to the WHO, the 2022 epidemic coincided with the rise of other vector-borne diseases such as Japanese Encephalitis and Scrub typhus.

For many, the consequences of climate change have become a reality. Nepal recognises the need for climate mitigation and adaptation through their Fifteenth or Five-year Plan, in line with the 2015 Paris Agreement. These adaptations include the implementation of programmes on the eradication of malaria, dengue and other vector-borne diseases.

There is no cure for dengue. Hospitals rely on PCR and other laboratory tests in facilities that are already under immense pressure and underfunded. | Michael Parfitt

In response to the 2022 outbreak, the WHO launched search-and-destroy campaigns in Nepal to eradicate dengue-carrying mosquitoes. The campaign also included the dissemination of 30,000 diagnostic kits and advocacy meetings in collaboration with schools and healthcare practitioners. Vaccination is also an effective strategy in combating dengue.

‘These [Fifteenth Plan] adaptations included the implementation of programmes on eradication of malaria, dengue and other vector-borne diseases.’

Targeted campaigns are important but may not be sustainable in the long term without addressing Nepal’s shortcomings in their water, sanitation and hygiene status. Challenges in delivering these services persist across urban and rural communities and will require financial attention for the nation’s public health to level up.

Heavy rainfall and flooding during 2022 may have contributed to the 2023 dengue epidemic, particularly affecting Kathmandu. | Michael Parfitt

The time for Nepal to create a sustainable and climate-resilient public health and water and sanitation infrastructure is now. More than ever countries are struggling to cope with climate change and the impact of changing weather on diseases such as dengue or other vector-borne or water-borne diseases is a challenge in which many find themselves unprepared.

Climate-vulnerable countries would benefit immensely from loss and damage reparations. Leaders from high-emitting countries have proposed at COP26 should help the people of Nepal and other South Asian countries to face the immense changes that are yet to come.

Featured Image: Michael Parfitt | @michaelparfittphoto

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