Listeriosis in Mexico: Clinical and epidemiological importance

Listeriosis is caused by Listeria monocytogenes, an important food-borne disease due to its clinical forms, high mortality rate, and the economic impact in both clinical and food production industries. In Mexico, the lack of epidemiological surveillance systems leads to the need of accurate data on the incidence of listeriosis and its association with food-borne disease. In this paper, we present data about the presence of this bacterium in food, reports related to clinical cases of listeriosis, and information of diseases in which L. monocytogenes may be involved. However, in most of these cases the etiology was not established. Given this, there´s a need to inform and warn the appropriate entities, to define strategies for the mandatory search of L. monocytogenes through the whole food production chain and clinical suspects, for the epidemiological importance and control of listeriosis in Mexico

Pantanos construidos para tratamiento de agua residual

La distribuciU?n espacial de contaminantes fI?sicos, quI?micos y microbiolU?gicos fue determinada durante un periodo de ocho meses en un pantano construido operado con agua de retrolavado. El sistema estudiado consistiU? de dos cuencas de sedimentación densamente vegetadas, un manantial artificial y un pantano de tres ha vegetado con Scirpus spp y Thypha domingensis. El tiempo de detenciU?n pro- medio fue de 33 dI?as. El sistema fue capaz de redu- cir SST y DBO5 al nivel de efluente secundario. Sin embargo, algunas porciones del sistema parecen no ser efectivas en la remociU?n de estos indicadores. Un incremento en la concentraciU?n de coliformes totales y fecales fue observado a lo largo del siste- ma, probablemente por un crecimiento o aportaciones adicionales por la fauna silvestre. Por otra parte, la reducciU?n de colifagos nativos fue de 46% para el periodo de estudio. Su baja reducciU?n su- giere que las condiciones clim·ticas y las aportacio- nes adicionales de material fecal pueden estar ocul- tando la verdadera tasa de remociU?n

Occurrence and quantitative microbial risk assessment of Cryptosporidium and Giardia in soil and air samples

Background: Cryptosporidium oocysts and Giardia cysts can be transmitted by the fecal–oral route and may cause gastrointestinal parasitic zoonoses. These zoonoses are common in rural zones due to the parasites being harbored in fecally contaminated soil. This study assessed the risk of illness (giardiasis and cryptosporidiosis) from inhaling and/or ingesting soil and/or airborne dust in Potam, Mexico. Methods: To assess the risk of infection, Quantitative Microbial Risk Assessment (QMRA) was employed, with the following steps: (1) hazard identification, (2) hazard exposure, (3) dose–response, and (4) risk characterization. Results: Cryptosporidium oocysts and Giardia cysts were observed in 52% and 57%, respectively, of total soil samples (n = 21), and in 60% and 80%, respectively, of air samples (n = 12). The calculated annual risks were higher than 9.9 × 10−1 for both parasites in both types of sample. Conclusions: Soil and air inhalation and/or ingestion are important vehicles for these parasites. To our knowledge, the results obtained in the present study represent the first QMRAs for cryptosporidiosis and giardiasis due to soil and air inhalation/ingestion in Mexico. In addition, this is the first evidence of the microbial air quality around these parasites in rural zones

Human adenovirus-associated health risk in the recreational waters of the Yal-ku lagoon in the Mexican Caribbean

The study objective was to evaluate human faecal contamination impacts in the Yal-ku lagoon in the Mexican Caribbean and to estimate adenovirus infection and illness risks associated with recreational exposure during water activities. A total of 20 water samples (10 from each site × two sites) (50 L) were collected monthly over a period of 12 months from two selected sampling sites in the swimming area of the Yal-ku lagoon. The occurrence of faecal-associated viruses was explored, and human adenovirus (HAdV) and pepper mild mottle virus (PMMoV) concentrations were quantified. A quantitative microbial risk assessment (QMRA) model was used to estimate exposure and subsequent adenovirus infection and illness risk for 1 h of swimming or snorkelling. Somatic and F + -specific coliphages occurred in 100% of the samples. Both HAdV and PMMoV were detected at a 60% frequency thereby indicating persistent faecal inputs. PMMoV concentrations (44–370 GC/L) were relatively lower than the concentrations of HAdV (64–1,000 GC/L). Estimated mean adenovirus risks were greater for snorkelling than for swimming by roughly one to two orders of magnitude and estimated mean illness risks for snorkelling were >32/1,000. Human faecal contamination is frequent in the Yal-ku lagoon, which is associated with human gastrointestinal illness. HIGHLIGHTS Human faecal contamination detected in a Mexican Caribbean lagoon.; The rainfall seasons posed the greatest risk.; Estimated risks were greater for snorkelling than for swimming by one to two orders of magnitude.; Estimated mean illness risks for snorkelling were >32/1,000.