Spatial distribution and cluster detection of zoonotic dog endoparasites in public parks from Gran Santiago, Chile.

The interaction between dogs and humans has increased significantly. This close contact could affect people's health by transmitting zoonotic parasites present in canine stools. Parks and public squares are places of contact with these agents. In this context, this work aimed to characterize the occurrence of zoonotic risk endoparasites in canine stool collected from the main urban parks of Gran Santiago and to determine whether spatial clusters were present among the detected parasites. For this, 468 stool samples were collected from 26 urban parks, and each sample was analyzed using the modified Telemann method and Ziehl-Neelsen stain. Zoonotic endoparasites were detected in all 26 urban parks (100%). Of the total analyzed samples, 145 (31.0%) were positive for at least one gastrointestinal parasite with potential zoonotic risk, identifying the following genera and species: Giardia sp. (12.2%), Toxocara spp. (9.6%), Cryptosporidium sp. (6.2%), Toxascaris leonina (3.2%), Cestode-like egg (2.6%), Ancylostomatidae eggs (1.7%), and Dipylidium caninum (0.9%). The highest infestation rates were recorded in parks in the northwest sector (Cerro Navia, Renca, and Estación Central) and the central sector (Santiago, San Miguel, and San Joaquín) of the sampled area. Local clustering of positive samples was assessed using the Bernoulli model of the spatial scan statistic for each parasite species detected, considering a purely spatial cluster analysis, showing statistically significant high-risk clusters only for Giardia sp. (RR = 2.96; p-value = 0.050) and Cryptosporidium sp. (RR = 6.60; p-value = 0.004). These results show a wide distribution of parasitic stages with zoonotic risk in the urban parks of Gran Santiago. In addition, there was an increase in the incidence of protozoan infections, such as Giardia sp. and Cryptosporidium spp., compared with previous studies, and the detection of high-risk spatial clusters. These results suggest a potential risk to public health and a change in the prevalence and distribution of parasites, which should be monitored regularly.