Dirofilaria repens in dogs from Assam, India

Abstract Objective To access the prevalence of Dirofilaria repens ( D . repens ) in dogs from Assam, India. Methods A total of 223 blood samples from local dogs were examined with conventional (wet film and Knott's concentration technique), serological (ELISA test using Snap4Dx kits) and molecular techniques (targeting internal transcribed spacer-2 region using panfilarial primers) in Guwahati, Assam, India. Results The study revealed 4 (1.79%) cases of asymptomatic canine dirofilariasis caused by D. repens . The blood samples were positive for D. repens with microfilaremia on wet blood film, at Giemsa stained smear and under Knott's concentration technique, but were negative at Snap®4Dx test (IDEXX Laboratory, Westbrook, USA) which is specific for Dirofilaria immitis . D. repens could be detected by molecular test. Further confirmation was obtained on the basis of DNA sequencing and homology searching by basic local alignment search tool. Sequence analysis revealed that the species prevalent in Guwahati was genetically distinct from the other D. repens reported from elsewhere. Conclusions Occurrence of D. repens in dogs from this part of India was recorded for the first time, confirming the presence of a autochthonous canine reservoir for the zoonotic filarial nematode in Assam, India, where three cases of human subcutaneous and ocular infection with D. repens (dirofilariasis) have been reported.