Tilapia is the most cultivated fish around the world. The fish’s environment can harbor bacteria, especially coliforms, which are not normal biota of fish. These microorganisms are contamination indicator groups (IGs) reflecting the possible presence of pathogens, which can compromise the safety of fishery products. The IGs prevalence was estimated in tilapia and water from 29 aquaculture farms. Total and fecal coliforms (TC, FC), mesophilic aerobic bacteria (MAB), S. aureus, E. coli, Salmonella sp., and Streptococcus sp., were investigated. In tilapia, TC and FC were detected in 64% and 48% of the samples, ranging from 4.0 x 101 to 9.8 x 105, and from 1.0 x 101 to 6.4 x 103 CFU/g, respectively; MAB were detected in 90% of the samples. In water, TC and FC were detected in 57% and 35% of the samples, oscillating from 1.0 x 101 to 2.28 x104, and from 1.0 x 101 to 1.2 x 103 CFU/mL, respectively. MAB were detected in 89% of the water samples. Mostly E. coli and Enterobacter agglomerans were detected. Generally, IGs concentrations meet the Mexican regulations; however, the tilapia’s microbiological quality must be continuously monitored.

Gnathostomosis, caused by Gnathostoma binucleatum, is a serious public health issue in Mexico. Although 2 other Gnathostoma spp., G. turgidum and G. lamothei, have been found in wild animals, their natural life cycle or their relation to human disease remains unclear. While we were conducting an epidemiological survey on Gnathostoma spp. in Sinaloa State, Mexico, we found an endemic area for G. turgidum in common opossums, Didelphis virginiana, located in Tecualilla, Sinaloa. The species identification was carried out by morphological and molecular biological methods. This is the first record of an endemic area for G. turgidum infection in opossums, D. virginiana, in the Americas.

Gnathostoma turgidum is a nematode that parasitizes the stomach of opossums, Didelphis virginiana. Despite its wide distribution in the Americas, its natural life cycle is poorly understood. Recently, we found an endemic area for G. turgidum infection in Sinaloa, Mexico (Diaz-Camacho et al., 2009). Based on sporadic surveys for several years, the prevalence was apparently high in summer and extremely low in winter. To confirm that this is really a seasonal variance, we conducted a longitudinal survey on G. turgidum infection in opossums from November 2007 to November 2008. The results showed amazing seasonal changes in the prevalence, with synchronized migration and maturation of worms in opossums. Between February and March, many juvenile worms, with occasional AL3, were found in the liver, but no worms were found in the stomach. Mature adult worms began to appear in the stomach around April and rapidly increased in number toward July, when all worms resided in the stomach. Then, the worms disappeared almost completely by November. These results suggest that G. turgidum is an annual parasite of the opossum, D. virginiana, in Mexico.

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Human gnathostomosis, a serious public health issue in Mexico, is endemic to Sinaloa. The disease is mainly caused by consumption of the raw meat of freshwater or estuarine fi shes infected with the advanced third stage larvae (AL3) of Gnathostoma binucleatum. In the present study, we examined estuarine turtles with a sample consisting of 23 Trachemys scripta and 5 Kinosternon integrum from Sinaloa, Mexico for the presence of Gnathostoma larvae; such examination was made by the pressing method of skeletal muscles between 2 glass plates. The results showed that both turtles harbored G. binucleatum AL3; identifi cation was achieved by morphology and also by PCR/sequencing of the ITS2 region of ribosomal DNA of the larvae. Infection prevalence was higher for K. integrum (80%) than for T. scripta (69.6%), but heavy infection (> 10 AL3/turtle) was observed in the larger sized individuals of T. scripta. Consumption of the raw meat of these turtles represents a risk to acquire the disease.