Using Background Sequencing Data to Anticipate DENV-1 Circulation in the Lao PDR

Area of Science:

• * Virology
• * Epidemiology
• * Public Health

Background:

• * Dengue fever is a significant public health concern in the Lao People's Democratic Republic (PDR), first detected in 1979.
• * While other dengue virus (DENV) serotypes have caused major outbreaks between 2012 and 2020, DENV-1 has consistently co-circulated.

Purpose of the Study:

• * To summarize epidemiological and molecular data for DENV-1 in Laos from 2016 to 2020.
• * To analyze the phylogenetic characteristics and circulation patterns of DENV-1 in the region.

Main Methods:

• * Review of epidemiological data on dengue cases in Laos.
• * Molecular analysis, including phylogenetic analysis of DENV-1 strains.
• * Serotyping tests to determine the prevalence of DENV-1.

Main Results:

• * DENV-1 circulated continuously in Laos between 2016 and 2020, accounting for 16% to 22% of serotyped cases.
• * Phylogenetic analysis identified the circulation of DENV-1 genotype I since at least 2008, with multiple clusters co-circulating.
• * Evidence suggests independent DENV-1 introductions into Laos, linked to regional circulation in Southeast Asia.

Conclusions:

• * The sustained circulation of DENV-1 indicates a low level of population immunity in Laos.
• * There is a persistent risk of a future DENV-1 epidemic.
• * Integrated surveillance is crucial for preventing major dengue outbreaks in the region.