# A preliminary survey of feline filarial parasites in Kerala State, India

## TL;DR

This study investigates filarial parasites in cats in Kerala, India, finding evidence of zoonotic species and suggesting the need for further research.

## Contribution

The study identifies Brugia malayi and Dirofilaria repens in cats using molecular techniques and highlights their potential epidemiological significance.

## Key findings

- Four cats (1.33%) tested positive for filarial parasites, including Brugia malayi and Dirofilaria repens.
- B. malayi isolates clustered with Thai feline isolates, while D. repens showed genetic continuity with Indian isolates.
- Low parasitemia in cats suggests a possible role as reservoir hosts for zoonotic filarial parasites.

## Abstract

Feline filarial parasites remain among the least investigated in India, despite the well-established endemicity of filariosis in canine and human populations. This study aimed to assess filarial infections in domestic cats in Kerala using both microscopy and molecular techniques, with a focus on evaluating their potential role as reservoir hosts. From September 2023 to February 2024, 300 owned cats presented to the University Veterinary Hospital, Mannuthy, were screened for circulating microfilariae using wet blood film examination. Four cats (1.33%) tested positive, of which three harbored sheathed microfilariae and one unsheathed. PCR amplification targeting the 5.8S–ITS2–28S ribosomal region of ribosomal DNA identified the sheathed forms as Brugia malayi and the unsheathed form as Dirofilaria repens. No co-infections were detected. Phylogenetic analysis of the 5.8S–ITS2–28S ribosomal sequences revealed that the B. malayi isolates clustered with previously reported feline isolates from Thailand, suggesting regional genetic relatedness. The D. repens isolate showed high sequence similarity to other Indian isolates, indicating genetic continuity across local strains. Although the parasitemia was lower than that reported in dogs and in cats from other endemic countries, the detection of zoonotic species in asymptomatic cats supports further investigation of the epidemiological significance of feline infections. Comprehensive, long-term studies involving molecular surveillance and vector ecology are recommended to clarify the epidemiological significance of feline hosts in filarial parasite transmission.