Co-Circulation of Dengue Virus Serotypes 1, 2, and 3 during the 2022 Dengue Outbreak in Nepal: A Cross-Sectional Study

Abstract

The largest dengue outbreak in the history of Nepal occurred in 2022, with a significant number of casualties. It affected all 77 districts, with the nation’s capital, Kathmandu (altitude 1300 m), being the hardest hit. However, the molecular epidemiology of this outbreak, including the dengue virus (DENV) serotype(s) responsible for this epidemic, remain unknown. Here, we report the epidemic trends, clinico-laboratory features, and virus serotypes and their viral load profiles that are associated with this outbreak in Nepal. Dengue-suspected febrile patients were investigated by routine laboratory, serological, and molecular tools, including a real-time quantitative polymerase chain reaction (qRT-PCR). Of the 538 dengue-suspected patients enrolled, 401 (74.5%) were diagnosed with dengue. Among these dengue cases, 129 (32.2%) patients who required hospital admission had significant associations with myalgia, rash, diarrhea, retro-orbital pain, bleeding, and abdominal pain. DENV-1, -2, and -3 were identified during the 2022 epidemic, with a predominance of DENV-1 (57.1%) and DENV-3 (32.1%), exhibiting a new serotype addition. We found that multiple serotypes circulated in 2022, with a higher frequency of hospitalizations, more severe dengue, and more deaths than in the past. Therefore, precise mapping of dengue and other related infections through integrated disease surveillance, evaluation of the dynamics of population-level immunity and virus evolution should be the urgent plans of action for evidence-based policy-making for dengue control and prevention in the country.

Largest dengue outbreak (2022) in Nepal

“…15,16 In 2019, highest numbers of cases were reported from Bagmati Provice again and least was reported from Karnali Province. However, during the COVID-19 pandemic period dengue reporting was overshadowed (2020 and 2021, the cases were only 530 and 540, respectively) [16][17][18] however, this reduction in dengue incidence/ transmission might be attributed to movement restriction during COVID-19 pandemic. 19 This was against the expectation of health planners (much bigger epidemic of dengue in Kathmandu was expected).…”

“…aegypti in Nepal was reported in 2009, suggesting some coincidence between the invasion of this species and the first dengue outbreak in Nepal in 2006. 23 18,25 Of these three serotypes, DENV-1 was predominant (57.1%) and DENV-3 (32.1%). 18 Significant increase in both the number of cases of dengue fever and the areas of outbreaks within Nepal in recent years has been attributed to global climate change and other associate factors.…”

“…23 18,25 Of these three serotypes, DENV-1 was predominant (57.1%) and DENV-3 (32.1%). 18 Significant increase in both the number of cases of dengue fever and the areas of outbreaks within Nepal in recent years has been attributed to global climate change and other associate factors. 26 As expected, this year an explosion of dengue particulalrly in Kathmandu occurred.…”

“…One study done by Khanal et al 29 has shown that 58% had good knowledge and 62% good practice regarding dengue fever in Nepal. In addition, a precise mapping of dengue and other related infections through integrated disease surveillance, evaluation of the dynamics of population-level immunity and virus evolution should be done for evidence-based policymaking 18 for the control of dengue infection in the country.…”

Molecular Investigation of DENV serotypes in the dengue outbreak of 2022 in Nepal

“…55 Nevertheless, the overall distribution of serotypes, from this study, was similar to other studies in Nepal, done during epidemic of 2022, where DENV1 was observed to be highly prevalent followed by DENV3. [56][57][58] Though Nepal has previously reported all four serotypes in the past, DENV1 and DENV2…”