Molecular prevalence of Dirofilaria sp. hongkongensis, among the dog population in Thiruvananthapuram, India

Human dirofilariasis is an emerging vector-borne zoonotic parasitic disease in India. Humans are accidental hosts. Symptomatic dirofilariasis, although uncommon is typically manifested in humans as pulmonary, ocular, or subcutaneous nodules. The present research reports the prevalence of the species, Dirofilaria sp. hongkongensis among the dog population in the Kani tribal settlements within the Agasthyamala Biosphere Reserve located at the southernmost end of the Western Ghats, Kerala. To study the prevalence, we conducted a random blood survey among the dog population in these tribal settlements in Thiruvananthapuram. Whole blood was collected from stray and domesticated animals. Genomic DNA was extracted and the microfilariae in the blood were characterized using the slide smear and COI-based marker specific to nematodes. After processing the data from the Sanger sequencer using BLAST, the sequences were submitted to GenBank. Over 25 % of dogs were found positive for Dirofilaria sp. hongkongensis, which is genetically identical to the strain causing human dirofilariasis as is shown by the phylogenetic analysis. The study reveals that the Kani tribes, who reside in deep forests, are particularly vulnerable to this strain of Dirofilaria sp. hongkongensis. Human case reports of this specific strain have been recorded in Kerala over the past decade. The effective elimination is ultimately impacted by a lack of knowledge regarding the mosquito vectors. Dirofilariasis in dogs and humans is on the rise, which demands both active disease surveillance and proper treatment.