Molecular identification of zoonotic hookworms in environmentally collected canine fecal samples in Northern Philippines

Background: Hookworm infections remain an important public health and veterinary concern in tropical and subtropical regions, particularly in communities with close human-animal interactions and limited sanitation. Dogs are recognized as reservoirs of zoonotic hookworms, yet species-level infection data in endemic areas remain lacking because the widely utilized microscopic examination of stool samples cannot differentiate morphologically indistinguishable hookworm eggs. Methods: Environmentally deposited canine fecal samples (n = 72) were collected from five barangays in Gonzaga, Cagayan, Northern Philippines. Samples were examined using formalin-ether concentration technique (FECT) and endpoint PCR targeting the ITS regions, followed by Sanger sequencing for species identification. Results: Hookworm ova were detected by coproscopy in 20 samples (27.8%), while the PCR assay yielded 24 positive samples (33.3%). Three hookworm species were identified using nBLAST alignment, with Ancylostoma ceylanicum as the predominant species, alongside single detections of A. caninum and N. americanus, the latter likely reflecting environmental contamination or coprophagic passage rather than true canine infection. There were no mixed-species infections identified. Conclusion: The predominance of the zoonotic hookworm A. ceylanicum in environmentally collected canine feces highlights the role of free-roaming dogs in zoonotic hookworm transmission in shared environments. Molecular species identification provided greater resolution than microscopy alone, underscoring the value of integrating PCR-based approaches with conventional coproscopy to strengthen zoonotic hookworm surveillance and better inform One Health interventions.