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INTRODUCTION: Dogs represent a potential public health risk because of the natural transmission of zoonotic parasitic infections. OBJECTIVE: To estimate the frequency and to determine factors associated with the presence of intestinal nematode eggs in dog feces collected in public parks of Mérida,Yucatán, México. MATERIALS AND METHODS: A total of 100 dog fecal samples collected from 20 public parks in two areas of Mérida were analyzed. Samples were processed by the centrifugation-flotation and the McMaster techniques to confirm the presence and to quantify the excretion of intestinal nematode eggs per gram of feces. The factors associated with the presence of nematode eggs were identified using the chi square univariate analysis. RESULTS: We found an 11% frequency of fecal samples positive for intestinal nematode eggs. Eggs of three species of parasites were identified: Ancylostoma caninum was the most common (10%), followed by Toxocara canis (10%), and Trichuris vulpis (1%). Most positive samples were infected with only one intestinal nematode (10%), and only 1 % was positive for a mixed infection by A. caninum and T. vulpis. The presence of stray dogs in public parks was an associated factor (p=0.046) with a higher number of fecal samples positive for intestinal nematode eggs. CONCLUSIONS: The frequency of intestinal nematodes in dog feces with zoonotic potential was high in parks of Mérida, Yucatán, México; samples from parks where there were stray dogs had a higher possibility of being positive.

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Resumen Introducción. Los perros representan un potencial riesgo para la salud pública debido a que transmiten infecciones parasitarias al hombre. Objetivo. Estimar la frecuencia y determinar los factores asociados a la presencia de huevos de nematodos intestinales en heces de perros recolectadas en parques públicos de Mérida, Yucatán, México. Materiales y métodos. Se analizaron 100 muestras de heces de perros recolectadas en 20 parques públicos de dos zonas de la ciudad. Las muestras se procesaron mediante las técnicas de flotación centrifugada y de McMaster para confirmar la presencia de huevos de nematodos intestinales y cuantificarlos por gramo de heces. Se determinaron los factores asociados a la presencia de los huevos mediante un análisis univariado de χ2. Resultados. Se encontró una frecuencia de 11 %. Se identificaron huevos de tres especies de parásitos y Ancylostoma caninum fue el más frecuente (10 %), seguido por Toxocara canis (1 %) y Trichuris vulpis (1 %). La mayoría de las muestras positivas presentaba infección con un nematodo intestinal únicamente (10 %) y solo el 1 % resultó positivo para infección mixta por A. caninum y T. vulpis. La presencia de perros sin dueño en los parques públicos fue el factor asociado (p=0,046) con un mayor número de heces positivas para huevos de nematodos intestinales. Conclusiones. En los parques de la ciudad se encontraron heces de perros con huevos de nematodos intestinales con potencial zoonótico; la probabilidad de que las muestras fueran positivas fue mayor en los parques con presencia de perros sin dueño.

Abstract Introduction: Dogs represent a potential public health risk because of the natural transmission of zoonotic parasitic infections. Objective: To estimate the frequency and to determine factors associated with the presence of intestinal nematode eggs in dog feces collected in public parks of Mérida,Yucatán, México. Materials and methods: A total of 100 dog fecal samples collected from 20 public parks in two areas of Mérida were analyzed. Samples were processed by the centrifugation-flotation and the McMaster techniques to confirm the presence and to quantify the excretion of intestinal nematode eggs per gram of feces. The factors associated with the presence of nematode eggs were identified using the chi square univariate analysis. Results: We found an 11% frequency of fecal samples positive for intestinal nematode eggs. Eggs of three species of parasites were identified: Ancylostoma caninum was the most common (10%), followed by Toxocara canis (10%), and Trichuris vulpis (1%). Most positive samples were infected with only one intestinal nematode (10%), and only 1 % was positive for a mixed infection by A. caninum and T. vulpis. The presence of stray dogs in public parks was an associated factor (p=0.046) with a higher number of fecal samples positive for intestinal nematode eggs. Conclusions: The frequency of intestinal nematodes in dog feces with zoonotic potential was high in parks of Mérida, Yucatán, México; samples from parks where there were stray dogs had a higher possibility of being positive.

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The objective of this study was to determine the seroprevalence to Ehrlichia spp. in dogs from Xcalak, Quintana Roo, Mexico, and the associated factors. Serum samples were obtained from 118 dogs and used in an indirect immunofluorescent assay test for the detection of antibodies against Ehrlichia spp. A questionnaire was used to obtain information about possible variables associated with seroprevalence. These variables were analyzed through Chi2 test and logistic regression. Dog seroprevalence of antibodies against Ehrlichia spp. was 64% (75/118). Fifty-two percent (61/118) of dogs had tick infestation which was identified as Rhipicephalus sanguineus sensu lato. Anemia was observed in 36% of dogs. Leucopenia (2.5%), thrombocytopenia (70%), and hemorrhage (14%) were also observed. Thirty-one percent (23/75) of dogs with anemia, 4% (3/75) of dogs with leucopenia, 80% (60/75) of dogs with thrombocytopenia, 17% (13/75) of dogs with hemorrhages, and 59% (44/75) of dogs with ticks were positive for Ehrlichia spp. antibodies. The factors associated with seroprevalence were age (1-3 and >3 years old, OR = 7.77 and OR = 15.39, resp.), tick infestation (OR = 3.13), and thrombocytopenia (OR = 3.36). In conclusion, seroprevalence of Ehrlichia spp. was high in the community of Xcalak and its associated factors were age, tick infestation, and thrombocytopenia.

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Ehrlichia canis is the etiological agent behind canine monocytic ehrlichiosis, and the tick Rhipicephalus sanguineus (Latreille) is its main vector. Blood smear and nested polymerase chain reaction (PCR) techniques were used to identify E. canis infection in dogs and R. sanguineus, and explore factors possibly associated with infection in dogs in Yucatan, Mexico. Blood samples were taken and ticks R. sanguineus collected from 50 dogs (10 house dogs and 40 in an animal control center). Data were collected on dog age, sex, body condition, and signs associated with platelet deficiencies (epistaxis). Blood smears were analyzed to identify E. canis morulae and generate platelet counts. Nested PCR analysis was done on blood samples and 200 ticks. A χ(2) test was done to identify factors associated with the E. canis infection in the tested dogs. The overall prevalence for infection, as determined by PCR, was 36% (18 out of 50). All positive dogs were from samples collected from the animal shelter, representing prevalence, for this sampling site, of 45% (18 out of 40). Morulae in monocytes were identified in only 4% of samples. Dog origin (i.e. animal control center) was the only variable associated with E. canis infection (P < 0.01). Male ticks had a higher (P < 0.05) infection rate than female ticks (24.5 vs 13.5%). It is concluded that E. canis infection is present in both dogs and the brown dog ticks R. sanguineus in Yucatan, Mexico.

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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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The aim of this study was to determine the prevalence of Dirofilaria immitis in dogs and to analyze risk factors associated with infection at Celestun, a coastal locality in southeast Mexico. Blood samples were collected from 279 asymptomatic individuals between August 2007 and March 2008 and analyzed by polymerase chain reaction technique. The association between D. immitis infection and sex, age group, and distance of residence from a wetland of dogs was statistically analyzed. Prevalence of D. immitis infection was of 59.8%. Age of individuals (>2 years) was a risk factor for infection with D. immitis (odds ratio 2.49, confidence interval 1.47-4.23, p=0.001). In conclusion, Celestun can be considered a focus of D. immitis infection with high levels of transmission among the local dog population, as confirmed by the high prevalence reported and the association of age (dogs >2 years) as a risk associated with infection.

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Chagas' disease is an important health problem in most Latin American countries, and a concern in dog populations, which act as a reservoir. We showed in previous studies that a therapeutic DNA vaccine could partially control the pathology after Trypanosoma cruzi infection in mice, and this vaccine may represent an alternative treatment for Chagas' disease. Here we evaluated the therapeutic efficacy of this vaccine in experimentally infected dogs for up to 2 months after infection. Our results suggest that DNA vaccine treatment may affect the immune response and delay Chagas' disease progression in T. cruzi-infected dogs, and confirm the potential of this novel treatment.

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