Dirofilariosis in dogs & humans in Kerala

691 The genus Dirofilaria includes various species that are natural parasites of dogs, cats, foxes and wild mammals. Dirofilaria immitis is the species occurring in the right ventricle and pulmonary artery of the dogs. The worm commonly known as dog heart worm, is widely dispersed and found in the tropics, subtropics and temperate zones. Another naturally occurring species commonly encountered in the subcutaneous tissues of dogs is Dirofilaria repens which has also been reported from different parts of the world. Mosquitoes belonging to the genera of Culex, Aedes, Armigeres and Anopheles have been incriminated as suitable vectors for this parasite, which take up the microfilaria (mf-L 1 ) while feeding on an infected host. In the mosquitoes, the mf develops to the infective 3rd stage larva (L 3 ) in the Malpighian tubules, and then migrates to the proboscis through the body cavity. Transmission takes place when a potential vector bites dogs or other hosts during a subsequent blood meal. The incidence of microfilariosis in dogs by examination of the peripheral blood was found to be 13.04 per cent in Calicut and 24.2 per cent in Thrissur. No specific staining procedure was adopted to identify the species involved. In a later study conducted in dogs at Ernakulam and Thrissur districts for a period of one year, the prevalence of microfilariosis was 7.59 per cent where histochemical staining method was employed to identify the species involved as D. repens. About 782 cases of D. repens infection in humans have been reported worldwide. The worms have been detected in the subcutaneous tissues of the body or in the subconjunctival space. The first report on human dirofilariosis from the state of Kerala was from a woman in Ottappalam in Palakkad district in 1999. We undertook this study to identify the worm specimens recovered from human beings from different parts of Kerala and also to estimate the prevalence of microfilariosis in dogs in Thrissur. Dirofilariosis in dogs & humans in Kerala