Molecular characterization of Toxocara canis in dogs from a shelter in the city of Riobamba

Abstract

Background: Parasitic infections represent a public health concern worldwide, with stray dogs serving as carriers of various parasites that pose a significant risk for the spread of parasitic diseases. Due to the limitations of conventional methods for accurate diagnosis, molecular diagnostic techniques are increasingly used; however, in Ecuador, extensive studies in this field are lacking. Objective: To determine the prevalence of parasitic infections and to perform the molecular characterization of Toxocara canis in dogs from a shelter in the city of Riobamba, Ecuador. Methods: An exploratory, descriptive, and non-experimental study was conducted using a sample of 150 dogs. Fecal samples were collected and analyzed through coproparasitological examination followed by molecular analysis. Results: A parasitic infection prevalence of 94.67% was observed, with Toxocara canis (35.75%), Giardia canis (32.40%), Chilomastix sp. (7.82%), Ancylostoma caninum (6.70%), Cystoisospora canis (5.59%), Entamoeba coli (7.26%), and Iodamoeba sp. (4.47%) being the most frequently detected. Both types of samples (feces and resuspension) tested microscopically positive for Toxocara canis. Polymerase Chain Reaction (PCR) confirmed the presence of the parasite, yielding a product size of 540 base pairs and identity percentages of 100% and 99.84%. Complete sequences obtained through Sanger Sequencing confirmed the identification of Toxocara canis. Conclusion: The findings clearly highlight the risk of zoonotic transmission between animals and humans. Molecular techniques demonstrated rapid and accurate results for the identification and discrimination of pathogenic parasites.