Abstract. Chagas disease represents a major public health concern in most of Latin America, and its control is currently based on vector control and blood bank screening. We investigated the geographic distribution and seasonal variations in triatomine populations in the Yucatan peninsula of Mexico to obtain entomologic data for the optimization of potential control programs. We collected domiciliated and peri-domiciliated Triatoma dimidiata from 115 houses in 23 villages distributed throughout most of the peninsula. A high abundance of bugs was observed in the northern part of the peninsula, indicating a prioritary area for vector control. Part of this distribution could be attributed to the type of vegetation. We also documented strong seasonal variations in T. dimidiata populations, with a higher abundance during the hot and dry season in April-June. These variations, associated with reduced year-round colonization of houses and the analysis of developmental stage structure, suggest that flying adults seasonally invading houses may play a larger role than domiciliated bugs in transmission of Trypanosoma cruzi to humans. The importance of this transmission dynamics may not be limited to the Yucatan peninsula, but may be a general mechanism contributing to natural transmission that should be taken into account in other regions for the design and optimization of control strategies.

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The prevalence of intestinal parasites in dogs and factors associated were studied in a rural community of Yucatan (southern Mexico), with special attention to those gastrointestinal parasites potentially transmitted to man. One hundred thirty dogs from 91 households were studied. Fecal samples were processed by the centrifugation-flotation and the McMaster techniques. To determine factors associated with zoonotic parasites in dogs, univariate analysis was performed, using sex, age, and body condition as independent variables. Variables with p < 0.2 were analyzed by a logistic regression. Of 130 dogs, 104 were positive for the presence of intestinal parasites, representing a prevalence of 80%. Eggs of four species of helminths (Ancylostoma caninum, Thichuris vulpis, Toxocara canis, and Dipylidium caninum) and coccidian oocysts were detected. A. caninum was the most prevalent parasite (73.8%), followed by T. vulpis (25.4%), T. canis (6.2%), D. caninum (2.3%), and coccidian oocysts (2.3%). The majority of dogs were infected by only one species of parasite (70/130, 53.8%). Mixed infection caused by two or three zoonotic parasites were discovered in 21.3% (30/130) and 3.1% (4/130), respectively. A. caninum showed the highest egg output (42.3% of dogs had ≥ 500 eggs per gram). Factors associated with zoonotic parasites were age (<2 years old; odds ratio = 5.30, p = 0.029) and body condition (poor body condition; odds ratio = 6.69, p = 0.026). In conclusion, young dogs from rural Yucatan, Mexico, with poor body condition had a higher prevalence of intestinal zoonotic parasites as these factors were associated with a higher risk of becoming infected.

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