VOLUME 19 NUMBER 1 (January to June 2026)

Opportunistic fecal sampling and PCR testing for canine schistosomiasis japonica surveillance in endemic settings

Among the challenges in animal surveillance for Schistosoma japonicum are the difficulty of collecting samples from free-roaming dogs and the low sensitivity of traditional diagnostics. This study evaluated opportunistic environmental fecal sampling combined with PCR as a surveillance tool for canine schistosomiasis japonica in selected endemic barangays of the northern Philippines. Dog stool samples (n = 72) were opportunistically collected in Gonzaga, Cagayan (6:00–8:00 AM) and analyzed using microscopy and PCR. All samples were examined for ova using the formalin–ether concentration technique (FECT). In parallel, DNA was extracted and screened using an internal control PCR; eligible extracts were then tested using an endpoint PCR assay targeting the S. japonicum SjR2 retrotransposon. While FECT detected no S. japonicum ova, PCR detected parasite DNA in 19.12% (13/68) of eligible samples. These findings provide proof of concept for non-invasive molecular surveillance using environmental dog fecal samples and suggest that this approach may help identify areas with canine shedding in endemic settings alongside existing One Health surveillance and control efforts.