Identification and molecular characterization of Dirofilaria sp. "hongkongensis" (Rhabditida: Onchocercidae) in wild-caught mosquitoes (Diptera: Culicidae): first report from India.

Abstract

Dirofilariasis is a globally significant emerging-zoonotic-disease caused by nematode parasites belonging to the genus Dirofilaria (Rhabditida: Onchocercidae) and is transmitted by mosquitoes (Diptera: Culicidae) of the Culicidae family. A recent study on molecular prevalence of Dirofilaria sp. "hongkongensis" To, 2012 (nomen nudum) among the dog population in Kerala indicated a high infection rate. However, no data are currently available on the vectors involved in the transmission of this disease. In this study, an entomological survey was conducted to detect natural infection and to characterize the Dirofilaria parasite from Kani tribal settlements in Thiruvananthapuram, India. A total of 356 mosquitoes were collected, morphologically identified, and analyzed for natural infection of Dirofilaria from 4 different villages in the study area. The species composition of the collected mosquito specimens comprised 10 species belonging to 6 genera, namely Anopheles, Aedes, Armigeres, Culex, Uranotaenia, and Heizmannia. Aedes albopictus (Skuse, 1895) was found to be the predominant species, followed by Armigeres subalbatus Coquillett, 1898. Out of these, 200 female mosquitoes were grouped by species into 31 pools, for genomic DNA extraction. Detection of the nematode parasite was performed using nematode-specific primers via conventional PCR, and the species was subsequently confirmed by sanger sequencing. Natural-infection of Dirofilaria sp. "hongkongensis" was identified in Ae. albopictus and Ar. subalbatus, with a minimum infection rate of 17.6% and 13.3%, respectively. This study represents the first report of natural-infection of Dirofilaria sp. among field-collected mosquitoes in India. These findings underscore the need for robust entomological-surveillance system to prevent potential future outbreaks.