Stray dogs in the tropical state of Chiapas, Mexico, harbour atypical and novel genotypes of Toxoplasma gondii.

Genotyping of Toxoplasma gondii remains a relevant topic of study, since genotypes can be related to the presentation and severity of toxoplasmosis. To date, 292 restriction fragment length polymorphism genotypes have been described around the world. Serosurveys in southeastern Mexico have documented exposure in over 70% of people and certain animals. Recently, we have described new genotypes and mixed infections in feral cats from Quintana Roo. Thus, the aim of this study was to genotype T. gondii and to describe its genetic variability, from naturally infected stray dogs of Chiapas, which has different geographical and climatic conditions from those found at the Yucatan Peninsula and the other parts of the country. Eleven stray dogs were captured and bled to obtain DNA, and then they were euthanized to perform necropsies and to collect target tissues. Diagnosis of T. gondii was done by quantitative real-time PCR (qPCR) and endpoint PCR. Genotyping was carried out, amplifying 12 polymorphic markers and 15 microsatellites. Atypical SAG3 gene products were cloned and sequenced. All blood samples of dogs were positive to T. gondii DNA by PCR. Two isolates were obtained from pooled heart and diaphragm tissue of two dogs. Two complete PCR-RFLP genotypes were identified (type BrIII and #28). Four animals had mixed infections. A new RFLP atypical allele for the SAG3 marker was observed; cloning and sequencing analysis of this locus revealed mixed infection by a strain identical to GT1, and one type I × II intragenic recombinant. The microsatellite analysis revealed that both isolates are atypical. Thus, atypical new genotypes of T. gondii and mixed infections were found in dogs of Chiapas. The results found here and in genotyping studies in México suggest that the southeastern region favours wide genetic diversity of T. gondii and the possible presence of virulent genotypes such as those found in central and South America.

Using Duddingtonia flagrans in calves under an organic milk farm production system in the Mexican tropics.

The reduction of the gastrointestinal nematode (GIN) larvae population in faeces of cattle treated with Duddingtonia flagrans chlamydospores on a farm under an organic production system in Chiapas, Mexico, was assessed. Seventeen Cebu/Swiss crossbreed grazing calves naturally infected with GIN, were randomly distributed into two groups and treated as follows: Group 1, an oral administration of 2 × 106D. flagrans chlamydospores/kg BW, every two days for 30 days; group 2, Control, without any treatment. Results indicated that the epg values in both groups remained similar (p > 0.05). The average number of (L3) from coprocultures from the group treated with D. flagrans had an important reduction (53.8%) with respect to the control group and it reached 75.3% maximum larval reduction at the 14th sampling; although, no statistic significance was observed (p > 0.05). Likewise, the average of larvae (L3) recovered from grass corresponding to the animals treated with D. flagrans diminished at 25.1% with respect to the control group (p > 0.05). A mixture of GIN genera including Strongyloides sp., Haemonchus sp., Cooperia sp., Trichostrongylus sp., Oesophagostomum sp. and Mecistocirrus sp., were identified from coprocultures. It was concluded that treatment with D. flagrans chlamydospores reduces the GIN larvae population in grass and in faeces of calves maintained under an organic milk production system.