JMIR Publications

ABSTRACT

Background:

Mosquitoes of genera Anopheles, Aedes, and Culex transmit diseases like malaria, dengue, chikungunya, Zika, Japanese encephalitis and Lymphatic filariasis. In Odisha, malaria poses a significant health challenge due to the region's favorable climate and topography for mosquito breeding and Plasmodium transmission. Anopheles mosquitoes, crucial for malaria transmission, thrive in various types of water bodies. Insecticide resistance presents a major concern, necessitating effective integrated vector management strategies. Understanding mosquito diversity is vital for public health interventions. Our study in southern Odisha aimed to explore seasonal variations in Anopheles populations across 11 districts that have been traditionally hyper-endemic for malaria.

Objective:

Our study aimed to investigate the seasonal effects on Anopheles mosquitoes across 11 districts in southern Odisha (Rayagada, Nabarangpur, Kalahandi, Nuapada, Balangir, Boudh, Kandhamal, Gajapati, Ganjam, Malkangiri, and Koraput). Additionally, we sought to generate data on mosquito species diversity, composition (types of Anopheles present), and abundance (number of mosquitoes) across these districts, considering their distinct environmental characteristics.

Methods:

We conducted a comprehensive study in southern Odisha, India, targeting 11 malaria-prone districts. Mosquito collections took place from March 2021 to February 2023, totaling 11,438 Anopheles and 631 belonging to other mosquito genera (Culicines). Both indoor and outdoor sampling methods were employed, and morphological identification was performed. We performed statistical analyses, including diversity indices (Shannon's, Simpson's, and Pielou's) and Canonical Correspondence Analysis (CCA), to evaluate mosquito species distribution across districts and seasons.

Results:

Over the study period, 10,807 Anopheles mosquitoes were collected across all seasons. Eighteen Anopheles species were identified, with An. subpictus dominating in summer (42.99%) March-June and the rainy season (46.60%) July-Oct. of 2021, but showing a significant decline later. An. culicifacies, a known malaria vector in the region, consistently comprised 30–38% of the population during summer and the rainy season. An. varuna peaked in winter of 2021 & 2022 at 35.56%. Diversity varied among districts, with Ganjam consistently exhibiting highest diversity (1.26–2.2). Seasonal fluctuations had a significant impact on mosquito diversity (p < 0.001), highlighting the greater influence of seasonality over district-specific factors on mosquito communities.

Conclusions:

This study emphasizes the importance of monitoring mosquito populations in Odisha, revealing their sensitivity to seasonal and geographic factors. Such insights are crucial for developing targeted and adaptable vector control strategies to combat malaria. Continuous assessment of mosquito diversity enables policymakers to implement evidence-based interventions tailored to the unique transmission dynamics of Odisha. These efforts contribute to the broader objective of malaria elimination in the country and the protection of public health for the general good.