Ovitrap surveillance in Sarawak, Malaysia: A comprehensive study

Area of Science:

• Medical Entomology
• Tropical Public Health
• Vector-Borne Disease Ecology

Background:

• Dengue fever remains a significant public health concern in Malaysia.
• Understanding the distribution and abundance of Aedes vectors is crucial for effective dengue control.
• Previous surveillance data in Sarawak may not reflect current vector dynamics.

Purpose of the Study:

• To determine the current distribution and abundance of Aedes larvae in Sarawak State, Malaysia.
• To identify residential areas at highest risk for dengue transmission based on vector density.
• To assess the dominant Aedes species and potential co-breeding vectors.

Main Methods:

• Ovitrap surveillance was employed across various residential settings (urban, suburban, rural, remote) in Sarawak.
• Larval indices, including the Ovitrap Index (OI), were calculated to quantify Aedes abundance.
• Mosquito species were identified, with a focus on Aedes aegypti and Aedes albopictus.

Main Results:

• The Ovitrap Index (OI) was highest in urban residential areas (mean OI = 90.97%), indicating greater larval presence.
• The mean number of Aedes larvae per ovitrap was significantly higher in urban areas (26.47 ± 1.62).
• Aedes albopictus was identified as the dominant dengue vector; Aedes aegypti was notably absent, while Armigeres species were found co-breeding.

Conclusions:

• Aedes albopictus is the primary dengue vector in Sarawak, Malaysia.
• All surveyed residential areas, particularly urban ones, are at risk of dengue transmission due to high Aedes larval indices (OI > 10).
• The absence of Aedes aegypti warrants further investigation into vector replacement or environmental factors.