Kerala - Thrissur   

Human filariasis parasite found in dogs

Microfilaria of Brugia malayi found in blood smear from infected dogs.

Thrissur: The presence of Brugia malayi in dogs has been clinically proven for the first time in the country in research conducted at Kerala Agricultural University’s College of Veterinary and Animal Sciences (CVAS).

Brugia malayi is a filarial parasite that causes lymphatic filariasis in human beings.

CVAS Dean E. Nanu told The Hindu that canine filariosis, a common disease seen in domestic and stray dogs in the State, was hitherto thought to be caused mainly by Dirofilaria repens, a comparatively harmless parasite of the filarial group.

“As far as we know, this is the first time that the presence of Brugia malayi in dogs is proven in a laboratory in the country,” he added.

Of the 75 cases studied by a team comprising Usha Narayana Pillai, associate professor with the Department of Clinical Medicine in CVAS, and V.R. Ambily, a post-graduate research scholar, 16 cases were found to have been caused by Brugia malayi. Most of the samples collected for the study were from Thrissur district.

“In Giemsa stain (used for the diagnosis of parasites), blood smear of the affected dogs revealed sheathed microfilaria in pink colour with two discrete overlapping nuclei at their tail end. It confirmed presence of Brugia malayi. The presence was further confirmed using an immunological kit designed to identify the parasite,” said Dr. Pillai.

Brugia malayi was identified by Lichtenstein and named by Brug in 1927 as distinct from Wuchereria bancrofti. They called it Filaria malayi. Buckley proposed Brugia as a separate genus in 1958.

Infected biting arthropods transmit the larvae. They migrate to the appropriate site of the host’s body and develop into microfilariae-producing adults. Brugia malayi was recently found to contain an endosymbiotic bacterium, Wolbachia, in its various stages of life.

Filarial species causing persistent microfilaremia in dogs include Dirofilaria immitis, Dirofilaria repens, Acantocheilonema reconditum (formerly Dipetalonema), Acantocheilonema dracunculoides, Brugia malayi, Brugia ceylonensis, Brugia phangi and Cercopithifilaria grassi. According to scientists, the geographic distribution of certain fliarial species is limited.

“Only Dirofilaria immitis and Dirofilaria repens have been reported in India. In Kerala, only Dirofilaria repens has been reported,” said Dr. Pillai.

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