Emergence of Ancylostoma braziliense infection in southern Indian dogs: Evidence from molecular sequencing

Canine ancylostomiasis is an emerging soil-transmitted parasitic zoonosis that poses significant public and animal health concerns. Although Ancylostoma caninum and A. ceylanicum have been widely reported in India, molecular sequencing report on A. braziliense from Southern India remain limited. Therefore, the present study aimed to molecularly characterize the predominant canine hookworm species in dog faecal and soil samples in the urban community of Chennai, Tamil Nadu, India. A total of 278 dog faecal and 243 soil samples were examined through flotation techniques using saturated sodium chloride and sodium carbonate, respectively. The hookworm species were identified using ITS-based primers, followed by restriction endonuclease digestion using HinFI. Microscopic examination revealed that 42.5 % and 6.6 % hookworm positivity in faecal and soil samples, respectively. Molecular assays identified 75.5 % as A. caninum, 10.9 % as A. braziliense and 13.6 % as mixed infections with both species, with an overall prevalence of 93.2 % in faecal samples. The higher prevalence of hookworm infection in dogs less than one year of age compared to older dogs, with mongrels being more affected than purebred dogs. Owned dogs showed slightly higher infection rates than free-roaming dogs and male dogs were more commonly infected, especially during the monsoon. Phylogenetic analysis showed that A. caninum isolates clustered closely with those from Japan, Vietnam and China, indicating genetic relatedness and possible shared ancestry. A. braziliense isolates formed a distinct monophyletic clade, separate from isolates in Malaysia, Brazil and the USA, suggesting regional divergence and the presence of unique genetic lineages in Southern India.