Key Findings and Comparisons From Analogous Case-Cluster Studies for Dengue Virus Infection Conducted in Machala, Ecuador, and Kamphaeng Phet, Thailand

Abstract

Dengue viruses (DENV) pose a significant and increasing threat to human health across broad regions of the globe. Currently, prevention, control, and treatment strategies are limited. Promising interventions are on the horizon, including multiple vaccine candidates under development and a renewed and innovative focus on controlling the vector, Aedes aegypti. However, significant gaps persist in our understanding of the similarities and differences in DENV epidemiology across regions of potential implementation and evaluation. In this manuscript, we highlight and compare findings from two analogous cluster-based studies for DENV transmission and pathogenesis conducted in Thailand and Ecuador to identify key features and questions for further pursuit. Despite a remarkably similar incidence of DENV infection among enrolled neighborhood contacts at the two sites, we note a higher occurrence of secondary infection and severe illness in Thailand compared to Ecuador. A higher force of infection in Thailand, defined as the incidence of infection among susceptible individuals, is suggested by the higher number of captured Aedes mosquitoes per household, the increasing proportion of asymptomatic infections with advancing age, and the high proportion of infections identified as secondary-type infections by serology. These observations should be confirmed in long-term, parallel prospective cohort studies conducted across regions, which would advantageously permit characterization of baseline immune status (susceptibility) and contemporaneous assessment of risks and risk factors for dengue illness.

Identification of risk factors and mosquito vectors associated with dengue virus infection in American Samoa, 2017

“…These findings are consistent with the expected clinical manifestations of dengue and findings in other jurisdictions where abundance of Ae. aegypti was associated with the presence of septic tanks [1,37,38]. Significant association of household use of a septic tank with DENV infection is consistent with previous research from other jurisdictions in which septic tanks were identified as sites of prominent production of Ae.…”

Individual, Household, and Community Drivers of Dengue Virus Infection Risk in Kamphaeng Phet Province, Thailand

“…Dengue virus transmission tends to occur over small spatial scales [6,7], resulting in the local clustering of cases in both space and time [8,9]. In addition, the diversity of circulating viruses has also been shown to be closely linked to the number of individuals living in the community [10].…”