Risk evaluation of Dengue virus transmission in Sargodha district (Punjab, Pakistan): a cross-sectional survey of Aedes mosquito infestation in houses and containers

We conducted a cross-sectional study of Aedes vectors to assess the risk of dengue transmission and arbovirus outbreaks in Sargodha district, Pakistani Punjab. Pupae and 3rd and 4th instar larvae of the predominant vectors, Aedes aegypti and A. albopictus mosquitoes, were collected from houses and containers using different tools. Containers were catalogued according to type, location, sun exposure, lid status, water type, and water status. Breeding Preference Ratio (BPR) and larval indices were calculated. Sixty-seven of 1782 houses and 28 of 1494 containers were found infested. Among positive containers, discarded tires had the highest BPR (2.22), followed by barrels and polythene sheets (1.72). The highest absolute counts of Aedes mosquitos were found in plastic drums, whereas other species of mosquitos were highly detected also in jerry cans. The water containers with the highest infestation rates were indoors, in shady locations, only partially covered, and held clean or rain water. Awan and Farooq colonies were identified as high-risk areas, based on a high House Index (5.97 and 4.93, respectively). Our survey suggests that local authorities should promptly address the issue of growing vector populations, particularly in the Awan colony (to be referred as Priority class II area), in order to stem the risk of future epidemics. The number of mosquitoes can be substantially reduced by better handling specific breeding sites and educating people to properly store water.