Prevalence of Zoonotic Parasites and Genetic Diversity of Ancylostoma caninum in Dogs From Machakos County, Kenya.

Introduction: Soil-transmitted helminths (STHs) remain a major global public health challenge, with dogs recognised as important reservoirs for several zoonotic species. In Kenya, data on the prevalence and genetic diversity of canine gastrointestinal helminths are scarce. This study investigated the prevalence of zoonotic helminths in dogs and characterised the genetic diversity of canine hookworms in Machakos County, Kenya.

Methods: A cross-sectional household-based survey was conducted across three sublocations representing low, medium and high human population density. Faecal samples were collected from 104 dog-owning households and examined using Mini-FLOTAC and zinc chloride sieving-flotation techniques. Hookworm species were identified using nested polymerase chain reaction targeting the mitochondrial cytochrome c oxidase subunit I gene, followed by DNA sequencing. Phylogenetic diversity of Ancylostoma caninum was assessed using median-joining haplotype network analyses.

Results: Mini-FLOTAC detected a higher prevalence of hookworm (89.4% vs. 81.6%), Toxocara spp. (45.2% vs. 19.7%) and taeniids (29.8% vs. 5.3%) compared to zinc chloride sieving-flotation. The latter identified additional parasites, including Trichuris spp. (9.2%), Spirocerca lupi (3.9%), Alaria spp. (1.3%) and Clonorchis sinensis (2.6%). A. caninum was the sole hookworm species identified, alongside genetically distinct A. caninum-like lineages. High genetic variability was observed, comprising 80 polymorphic sites and 40 haplotypes, of which 31 were singletons, seven occurred in two sequences each and two were represented by five and six sequences. Haplotype network and phylogenetic analyses revealed high genetic diversity and weak population structuring in A. caninum, with Kenyan isolates clustering with global lineages while exhibiting local diversification. We also report the first molecular confirmation of Angiostrongylus vasorum in domestic dogs in Kenya.

Conclusions: These findings underscore dogs as key reservoirs of zoonotic helminths and highlight the need for strengthened surveillance and integrated One Health strategies incorporating molecular diagnostics and targeted education within dog health programmes in line with the WHO NTD Roadmap.