Acta Scientiae Veterinariae, 2015. 43: 1307. RESEARCH ARTICLE Pub. 1307 ISSN 1679-9216 1 Received: 22 March 2015 Accepted: 20 August 2015 Published: 25 September 2015 1 Medicina Veterinaria y Zootecnia, Centro Universitario UAEMex-Amecameca. 2 Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, D.F., México. 3 Maestría en Ciencias Agropecuarias y Recursos Naturales, Universidad Autónoma del Estado de México. 4 Doctorado en Ciencias Agropecuarias y Recursos Naturales, Universidad Autónoma del Estado de México. CORRESPONDENCE: C. Romero [cromeron@ uaemex.mx - Tel.: 01 (597) 9782158]. Carretera Amecameca Ayapango Km 2.5. C.P. 56900 Amecameca de Juárez, México. Prevalence of Intestinal Parasites with Zoonotic Potential in Canids in Mexico City Camilo Romero 1 , Germán Eduardo Mendoza 2 , Miguel Angel Pineda 1 , Nadyeli Nava 3 , Linda Guiliana Bautista 1 & Rafael Heredia 4 ABSTRACT Background: In Mexico City, there are 1.2 million dogs of which 10% are strays, which produce about 182 tons of feces per year. Among the intestinal parasites with zoonotic risk from dogs are Ancylostoma, Toxocara, Giardia and Dipylidium. These pathogens can be found in standard human environments, such as water, soil, food, parks, and contamination from dog feces, and represent a high risk to persons. Therefore it is important to promote prophylactic measures, which are based on hygiene, having pet deworming programs and control of stray dogs. The objective was identifying Toxocara spp., Giardia spp., Dipylidium caninum, Ancylostoma spp. and Coccidia in canids from the downtown area of Mexico City. Materials, Methods & Results: The study was conducted in Mexico City. A total of 1603 pet feces were collected and were classified according to gender and age (young animals < 1 year and adults > 1.1 years). Microscopic diagnosis of parasites was achieved using the flotation technique of Willis. The proportion of contamination was considered as the percentage of positive samples out of all collected samples. The number of parasite eggs in each sample was counted, and eggs were then identified by structure and morphometry, to provide an additional measure of the degree of parasitization (number of eggs g -1 feces). Prevalence was analyzed using the Chi-square (χ²) test to compare age groups and gender, while the aver- age number of parasites per gram of feces was analyzed using a “t” test with a confidence level of P < 0.05. The results showed that 13.10% (210) of the dogs were positive for some type of gastrointestinal parasite (Toxocara spp., Coccidia, Ancylostoma spp., Giardia spp., Dipylidium caninum) of which 115 (13.18%) were males and 95 (12.99%) females, with no gender difference (χ² = 0.013, P = 0.99). Giardia spp. was found in 25 young animals (6.9%) and 50 adults (4.0 %) whereas Toxocara spp. was less common (3.3% of young animals and 3.7% of adults). Disscusion: The results of this study show lower prevalence rates than other reports from around the world. In our study, only 30 dogs were positive out of 1603 samples. Our sampling revealed a higher prevalence in males, but with a much lower incidence of A. caninum. The low incidence of A. caninum can be attributed to the fact that most pet dogs have been subjected to a deworming program. Several studies agree that dogs aged less than 5 months are more susceptible to this protozoan, because Giardia spp. can complete its life cycle by this age, and some dogs do not undergo an adequate deworming program. We observed the same effect of age, but the prevalence in Peru was four times greater than that in Mexico (4.0%). Several studies have shown that the soil of public parks presents an important source of infection of this zoonotic parasite and has a significant impact on public health. In most studies the prevalence varies between males and females, being higher in males, and appearing more frequently in younger animals. This information should be taken into account in the prevention and control of these zoonotic parasites, involving implementing deworming programs and avoid- ing fecal contamination of soil, water and food, encouraging responsible pet ownership, implementing the control of street animals and thus reducing the impact of this zoonotic problem. The parasite burden in the feces of dogs in the downtown area of Mexico City can be considered low but remains a potential risk factor for humans. Keywords: canine, parasites, risk factor, zoonosis, fecal examination.