Dengue outbreak in Pakistan: Mapping the distribution of vector mosquitoes with DNA barcodes

Mosquitoes are primary vectors of several serious human diseases including dengue fever. Recent epidemics of this viral-mediated disease in some urban areas of Punjab province have generated interest in the distributional patterns of the mosquito species found in this tropical region. Sequence variation in the barcode region of the COI gene was used to identify mosquito species, enabling investigation into the differing levels of dengue fever in the province. Barcode analysis of 1425 mosquitoes from 300 localities in Punjab during 2012 revealed 29 mosquito species most in three genera, Culex, Aedes, and Anopheles. Culex quinquefasciatus was the most prevalent comprising 76% of all specimens. Sequence analysis also revealed seven species of Aedes, including A. aegypti and A. albopictus, the known vectors of dengue virus, and three of those species were morphologically cryptic. Although A. aegypti and A. albopictus comprised only 5% of the catch, both species were present throughout the province.  The detection of cryptic species among the vectors warrants the use of molecular methods to forecast vector populations for dengue management. Presence of dengue-vector mosquito species may not be the only cause of high dengue incidence in some areas and low in the others.