To evaluate the serological status for Trypanosoma cruzi, Toxoplasma gondii and Leptospira interrogans antibodies in free roaming dogs and cats from a marginated rural community in Yucatan Mexico, 100 households were visited and animals sampled. From the 106 samples, 93 were from dogs and 13 were from cats. Frequency of positive results for T. gondii, T. cruzi and Leptospira spp was 97.8%, 9.7% and 45.2% for dogs and 92.3%, 0.0% and 15.2% for cats, respectively. No associations with age, sex and body condition was found for T. gondii and Leptospira spp neither for the place where pets sleep, fumigation or presence of triatomes in the household in the case of T. cruzi. For leptospirosis the most common serovars found were Canicola, Autralis and Bratislava in dogs and cats with titres of 100 or 200 with exception of one dog with a titre of 400. The high frequency of seropositive dogs suggests a high circulation of the agents in the population of free roaming owned dogs and cats probably due to the lack of control of the reservoirs and vectors involved. Domestic animals in those rural communities can be sentinels to assess the risk of human exposure in the rural communities.
