Abstract
Larval surveillance is the central approach for monitoring dengue vector populations in Indonesia. However, traditional larval indices are ineffective for measuring mosquito population dynamics and predicting the dengue transmission risk. We conducted a 14-month ovitrap surveillance. Eggs and immature mosquitoes were collected on a weekly basis from an urban village of Bandung, namely Sekejati. Ovitrap-related indices, namely positive house index (PHI), ovitrap index (OI), and ovitrap density index (ODI), were generated and correlated with environmental variables, housing type (terraced or high-density housing), ovitrap placement location (indoor or outdoor; household or public place), and local dengue cases. Our results demonstrated that Aedes aegypti was significantly predominant compared with Aedes albopictus at each housing type and ovitrap placement location. Ovitrap placement locations and rainfall were the major factors contributing to variations in PHI, OI, and ODI, whereas the influences of housing type and temperature were subtle. Indoor site values were significantly positively correlated to outdoor sites’ values for both OI and ODI. OI and ODI values from households were best predicted with those from public places at 1- and 0-week lags, respectively. Weekly rainfall values at 4- and 3-week lags were the best predictors of OI and ODI for households and public places, respectively. Monthly mean PHI, OI, and ODI were significantly associated with local dengue cases. In conclusion, ovitrap may be an effective tool for monitoring the population dynamics of Aedes mosquitoes, predicting dengue outbreaks, and serving as an early indicator to initiate environmental clean-up. Ovitrap surveillance is easy for surveyors if they are tasked with a certain number of ovitraps at a designated area, unlike the existing larval surveillance methodology, which entails identifying potential breeding sites largely at the surveyors’ discretion. Ovitrap surveillance may reduce the influence of individual effort in larval surveillance that likely causes inconsistency in results.
Highlights
Dengue infection is endemic in 90% of the districts and cities in Indonesia [1]
The results demonstrated that two dengue vector mosquitoes, A. aegypti and A. albopictus, were present in the study area, and A. aegypti was more prevalent than A. albopictus
We observed an interactive relationship between ovitrap placement and rainfall in the dynamics of ovitrap-related indices; understanding this relationship allows for timely initiation of vector control and intervention strategies
Summary
Dengue infection is endemic in 90% of the districts and cities in Indonesia [1]. various vector control programs have been implemented since 1968, primarily by the Ministry of Health, the data demonstrate that the nationwide spread of dengue infection sharply increased the annual incidence of dengue hemorrhagic fever (DHF) over 50 years from just 0.05 cases per 100,000 persons per year in 1968 to 77.96 cases per 100,000 persons per year in 2016 [2]. Unlike in previous years, where dengue cases usually subsided toward the end of the wet season in March, the dengue case outbreak in 2020 lasted until June, registering 100–500 cases per day [3]. This change in the epidemic pattern does not portend a future trend, but it does warn that dengue prevalence may get worse if not controlled. Wijayanti et al [11], who conducted a dengue vector surveillance study in Banyumas regency, West Java, Indonesia, provided compelling evidence that traditional larval indices are inadequate indicators for predicting dengue transmission risk, partly because of disparities in the vectorial capacity of Aedes mosquitoes across regions and shortcomings of the diagnostic tools. Vector surveillance has usually been implemented for a short period, and sampling techniques have not been standardized among surveyed areas owing to a shortage of funds
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