Seroprevalence of Schistosoma japonicum Infection Among Dogs and Water Buffaloes Using Recombinant Antigen ELISA in New Corella, Davao del Norte, Philippines.

PURPOSE

Animal reservoirs are important targets for controlling and eliminating schistosomiasis. Prevalence studies showed that dogs (Canis familiaris) and water buffaloes (Bubalus bubalis) are important reservoirs of S. japonicum. Previous studies have validated the use of the recombinant proteins Sj1TR, Sj7TR, and SjTPx-1 in ELISA as diagnostics for dogs and water buffaloes from schistosomiasis-endemic areas. In this study, we aimed to determine the seroprevalence of S. japonicum among dogs and water buffaloes in New Corella, Davao del Norte, Philippines, using the recombinant proteins Sj1TR, Sj7TR, and SjTPx-1 in ELISA format.

METHODS

Fecal and serum samples were collected from dogs (n = 63) and water buffaloes (n = 57). Schistosome-positive samples were detected using formalin-ether concentration technique (FECT), stool polymerase chain reaction, and enzyme-linked immunosorbent assay (ELISA) using soluble egg antigen (SEA), rSj1TR, rSj7TR, and rSjTPx-1. Positivity rates, sensitivity, specificity, predictive values, accuracy, and kappa values were calculated.

RESULTS

Mean positivity rates for schistosome infection were high for both dogs (x = 15.40%) and water buffaloes (x = 6.32%). On dogs, the sensitivity and specificity of the tests are as follows: 66.67% and 100% for rSj7TR-ELISA, while 100% and 93.33% for rSjTPx-1-ELISA, respectively. rSjTPx-1-ELISA showed the highest agreement with stool PCR among all diagnostic tests, with an overall kappa value of 0.824. On water buffaloes, the sensitivity and specificity of both rSj1TR-ELISA and rSjTPx-1-ELISA are 100.0% and 98.15%. Both tests also had an overall kappa value of 0.84.

CONCLUSION

To ensure elimination and prevention of schistosomiasis in humans, the use of validated serological diagnostics such as recombinant antigen ELISA is preferable for field detection in animals, especially in resource-limited areas.