Keywords
Aedes aegypti
Aedes albopictus
Insecticide resistance
Attitudes and practices
Laos
Categories
How to Cite
Abstract
Objective: To clarify the species composition, biting rhythm, seasonal fluctuation, and insecticide resistance of dengue vectors in residential areas of northern (Luang Prabang), central (Vientiane), and southern (Attapeu) Laos, and to analyze residents' knowledge, attitudes, and practices (KAP) regarding dengue prevention and their association with infection. Methods: From 2024 to 2025, human landing catches (HLC) with full personal protection and larval container indices were conducted in three sites. WHO adult contact tube bioassays were performed in Luang Prabang and Vientiane to determine resistance to five insecticides. Structured questionnaires were administered, and laboratory-confirmed dengue infection history was analyzed using multivariable logistic regression. Results: In Luang Prabang, 1,847 adult mosquitoes (2 subfamilies, 5 genera, 17 species) were collected; Aedes aegypti and Ae. albopictus accounted for 1.85% (34) and 2.38% (44), respectively. Biting peaks occurred at 09:00 and 18:00. BI/HI/CI peaked in August–September, with case peaks in October. In Vientiane, 2,156 adults (2 subfamilies, 6 genera, 18 species) were collected; Ae. aegypti and Ae. albopictus accounted for 2.89% (62) and 1.56% (34). Biting peaks were at 08:30–09:30 and 17:30–18:30; BI/HI/CI peaked in May–July, with case peaks in July–August. In Attapeu, 2,341 adults (2 subfamilies, 6 genera, 19 species) were collected; Ae. aegypti and Ae. albopictus accounted for 4.12% (96) and 2.86% (67). Biting peaks were at 08:00–09:00 and 17:00–18:00; BI/HI/CI peaked in April–May, with case peaks in June. In Luang Prabang, 24 h corrected mortality of Ae. aegypti to permethrin, lambda-cyhalothrin, and deltamethrin was 67.53%, 25.47%, and 72.63% (resistant); to fenitrothion and propoxur was 100% and 98.82% (susceptible). In Vientiane, mortality to permethrin and deltamethrin was 58.24% and 65.38% (resistant), with resistance more severe than in Luang Prabang. Multivariable analysis showed that children/adolescents (<18 years) had higher infection risk across all three sites (OR=2.15–2.78). Active larval source reduction significantly lowered infection risk (OR=0.35–0.48). Significant north-south gradients were observed in vector density, seasonal peaks, and pyrethroid resistance. Conclusion: Significant north-south gradients exist in vector ecology, seasonal peaks, and insecticide resistance in Laos. Larval source management remains key to effective prevention, and differentiated, site-specific integrated vector management is urgently needed.
References
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