Entomological investigations of dengue vectors in epidemic-prone districts of Pakistan during 2006–2010.

ABSTRACT

Intensive entomological investigations were carried out in seven dengue epidemic-prone districts of Pakistan, classifying them into three geographical regions, viz. southern, central and northern Pakistan. A total of 5132 water habitats from 2136 households in and around dengue-positive houses were sampled. Additionally, 264 samples each at least 30 metres away from dengue-positive houses were also collected from outdoor habitats. Only indoor samples data were used for the estimation of entomological indices. House Index, Container Index and Breteau Index were estimated at 39.42%, 27.96% and 67.20 respectively. Underground water tanks showed the highest (42.38%) positivity, followed by earthen pots (36.97%), drums (33.38%) and the least (4.58%) from discarded containers. From outdoor sites, only 5.05% (n=14) samples were found positive. Aedes aegypti and Aedes albopictus species exhibited a distinct association with different geographical regions. In the south of the country only Ae. aegypti was recorded in all (n=452) positive habitats while in the central part, both Ae. aegypti and Ae. albopictus were reported from 88.2% (n=253) and 11.8% (n=34) of the total 287 positive habitats respectively. In the north/submountainous region, 88.45% (n=628) of 710 positive samples were found infested with Ae. albopictus. Both species showed a significant population-rising trend from September to November, similar to the dengue case-load trend.