Widespread occurrence of benzimidazole resistance SNPs in the canine hookworm,Ancylostoma caninum,in Australia

Abstract

AbstractCanine hookworm (Ancylostoma caninum), a gastrointestinal nematode of domestic dogs, principally infects the small intestine of dogs and has the potential to cause zoonotic disease. In greyhounds and pet dogs in the USA,A. caninumhas been shown to be resistant to multiple anthelmintics. We conducted a molecular survey of benzimidazole resistance inA. caninumfrom dogs at veterinary diagnostic centers in Australia and New Zealand. First, we implemented an ITS-2 rDNA deep amplicon metabarcoding sequencing approach to ascertain the species of hookworms infecting dogs in the region. Then, we evaluated the frequency of the canonical F167Y and Q134H isoform-1 β-tubulin mutations, which confer benzimidazole resistance, using the same sequencing approach. The most detected hookworm species in diagnostic samples wasA. caninum(90%; 83/92); the related Northern hookworm (Uncinaria stenocephala) was identified in 11% (10/92) of the diagnostic samples. There was a single sample with coinfection byA. caninumandU. stenocephala. Both isoform-1 β-tubulin mutations were present inA. caninum, 49% and 67% for Q134H and F167Y, respectively. Mutation F167Y in the isoform-1 β-tubulin mutation was recorded inU. stenocephalafor the first time. Canonical benzimidazole resistance codons 198 and 200 mutations were absent. Egg hatch assays performed on a subset of theA. caninumsamples showed significant correlation between IC50to thiabendazole and F167Y, with an increased IC50for samples with >75% F167Y mutation. We detected 14% of dogs with >75% F167Y mutation inA. caninum. Given that these samples were collected from dogs across various regions of Australia, the present study suggests that benzimidazole resistance inA. caninumis widespread. Therefore, to mitigate the risk of resistance selection and further spread, adoption of a risk assessment-based approach to limit unnecessary anthelmintic use should be a key consideration for future parasite control.HighlightsHigh prevalence of benzimidazole resistance mutations in Australian canine hookworms.Ancylostoma caninumdetected in 90% of samples andUncinaria stenocephalain 11% of diagnostic samples.F167Y and Q134H mutations found inA. caninumand F167Y inU. stenocephala.Egg hatch assay confirms correlation between F167Y mutation and benzimidazole resistance.