Dirofilariasis

Abstract

Dirofilariasis, commonly known as heartworm disease, is a parasitic zoonosis caused by several species of Dirofilaria. Sylvatic life cycle involving an arthropod vector maintains the parasite among different animals. Dirofilaria immitis causes pulmonary dirofilariasis in humans and cardiopulmonary dirofilariasis in animals. Dirofilaria repens and other members of Nochtiella subgenus are mainly responsible for subcutaneous/ocular dirofilariasis. Infection in humans is considered accidental and dead-end and is discovered incidentally. Pathogenesis of dirofilariasis is complicated due to migratory larvae and immunological response of the host. The presence of the endosymbiont bacteria Wolbachia sp. adds a further twist in the immunopathogenesis by shifting the Th2 response to Th1 type. While the impact on human health is indirect in terms of cost of differential diagnosis like workup for malignancy, veterinary importance has grown enormously. Although the parasitic diagnosis is based on easy to overlook histopathological clue of parasitic remnants in humans, microfilariae isolated from animals need expert microscopy to characterize. Paucity in prudent diagnostics and immunological jeopardy associated with the treatment both pose challenges for this disease.KeywordsDirofilariasisPulmonary noduleCanine heartwormEndosymbiontKnott testDirofilaria genome