KATHMANDU, JULY 10

With the monsoon rain hammering Nepal, health stakeholders are warning of a potential dengue outbreak across the country.

The mosquito-borne disease, first reported in Nepal in 2004, has become a recurrent issue. Dengue spreads through the bite of infected Aedes mosquitoes, primarily Aedes aegypti and Aedes albopictus, which breed in stagnant water-a common occurrence during the monsoon season.

Understanding Dengue

Dengue fever, believed to have originated in non-human primates and emerged in humans roughly 500-1,000 years ago, causes symptoms such as high fever, headaches, severe eye pain, joint pain, and general body discomfort. In severe cases, known as the Critical Phase, patients experience a drop in platelet count, leading to plasma leakage, hemorrhage, shock, and severe organ impairment.

Once infected, humans become the main carriers of the virus, passing it on to uninfected mosquitoes. The virus stays in the blood of an infected person for 2-7 days, typically during the fever period. After an incubation period of 4-10 days, infection with any of the four dengue virus types can cause a range of illnesses, though most infections are asymptomatic or very mild.

Recovery from one dengue virus type provides lifelong immunity to that type but only partial and short-term protection against the other three types. Evidence suggests that infection with different types increases the risk of severe dengue. Severity depends on factors like secondary infection, age, and other health conditions such as diabetes and kidney disease.

According to the World Health Organization (WHO), there is no specific treatment for dengue; however, timely detection of cases, identifying any warning signs of severe dengue infection, and appropriate case management are key elements of care to prevent patient death and can lower fatality rates of severe infection.

History of Dengue in Nepal

Nepal's first dengue case was reported in a traveler returning from India in 2004. Although there were no cases in 2005, the virus resurfaced in 2006 and has intermittently affected the country since. Significant outbreaks occurred in 2006 and 2010, with the presence of all four serotypes confirmed in the country.

From 2007 to 2009, sporadic cases and outbreaks were recorded. In 2010, dengue epidemics began affecting both lowland and mid-hill areas. In 2011, 79 confirmed cases were reported across 15 districts, with the highest incidence in Chitwan. In 2012, 183 confirmed cases were reported, with a significant outbreak in Jhapa district.

By September 2022, Nepal had experienced 28,109 confirmed and suspected dengue cases and 38 confirmed deaths. In 2023, approximately 51,143 people suffered from dengue infections. Studies by the Epidemiology and Disease Control Division (EDCD) and National Public Health Laboratory (NPHL) have identified all four subtypes of the dengue virus circulating in Nepal: DENV-1, DENV-2, DENV-3, and DENV-4.

According to the Health Ministry, DENV-2 was the most prevalent serotype circulating in the country in 2023. In 2022, the cases of DENV-1 and DENV-3 were more common.

Current Situation

As of July 4, 2024, dengue infection has spread to 73 districts in Nepal, with the highest number of cases in Kathmandu, Jhapa, and Chitwan. The government has listed dengue as one of the 52 infectious diseases under the Public Health Service Act, 2075, emphasizing the need for vigilance and preventive measures.

Due to daily rain, dengue infections have increased. The Health Ministry reports that 1,432 people in 73 districts have been infected as of July 4, with only Mustang, Dolpa, Jumla, and Humla districts unaffected. The ministry predicts that the higher-than-average monsoon will favor mosquito breeding, increasing dengue cases.

Preventive Measures

The Epidemiology and Disease Control Division projects high virus risks between the Nepali months of Asar, Shrawan, Bhadra, and Ashwin. It urges stakeholders to take measures to destroy larvae and clear mosquito habitats, ensuring essential supplies like dengue kits, cetamol, and Jeevan Jal are available for those affected.

In response, Kathmandu Metropolitan City advised citizens in June to take precautions against dengue fever and conduct a larvae destruction campaign as well as clean the stagnated pools of water in the metropolis. Biratnagar Metropolitan City launched a search and destroy campaign targeting mosquito larvae across all 19 wards. Dr. Dilip Kumar Yadav, coordinator of the metropolis's Health Division, emphasized preventing water accumulation to control dengue. According to him, the metropolis is littered with mediums that mosquitoes thrive in, including tires, dishes, bottles, and areas behind coolers and air conditioners.

Hemraj Joshi, Vector Control Officer at the Sudurpaschim Province Health Directorate, highlighted the high dengue risk in the Terai region of Sudurpaschim due to continuous rainfall. 'As the rainfall starts and water gets collected in the abandoned water containers, the risk of dengue infection will increase in the Terai region,' he warned. Joshi also noted the rising prevalence of mosquito-borne diseases, including malaria, in hilly areas.

Globally, an estimated 390 million people are infected with the dengue virus annually, with 96 million showing clinical symptoms. Before 1970, only nine countries had severe dengue epidemics; today, the disease is endemic in over 100 countries. In Nepal, dengue cases typically occur between September and November, following the monsoon season.

Due to a large number of susceptible people, human movement, ignoring possible mediums of transmission, the presence of Aedes mosquitoes, and all four dengue serotypes, dengue is expected to remain a significant public health concern in Nepal, especially in urban areas like Kathmandu. Dengue was first detected in Kathmandu during the 2010, and, according to the 2011 survey by EDCD, there is a high possibility of a dengue outbreak in Kathmandu due to the large number of mosquitoes that carry the dengue virus.