These data indicate the presence of multiple sources of Salmonella infection in the DCC, posing a complex situation for infection control.

SUMMARYThe presence of Salmonella enterica and serologic evidence of infection by Leptospira interrogans, were detected in the opossum Didelphis virginiana in a semi-urban locality of the Yucatán State, México. Ninety-one opossums were captured during the period April 1996 and May 1998. From a total of 17 feces samples, four Salmonella enterica subsp. enterica serotypes (Sandiego, Newport, Anatum, and Minnesota), and one Salmonella enterica subsp. arizonae serovar O44: Z4,Z23:-were isolated. Some opossums presented mixed infections. From 81 sera samples, four (4.9%) were positive to antibodies to Leptospira serovars pomona and wolfii. Both animals infected with Salmonella enterica and those serologically positive to Leptospira interrogans were captured in peridomestic habitat. Opossums infected with Salmonella enterica, were captured in dry season, and those seropositive to Leptospira interrogans during the rainy season. The implications of infection and reactivity of these zoonotic pathogens in D. virginiana in the Yucatan state are briefly discussed. KEYWORDS: Didelphis virginiana; Salmonella enterica; Leptospira interrogans; Yucatán; México.Opossums of the genus Didelphis have been frequently found infected with several zoonotic diseases 7 . Didelphis virginiana occurs widely in México including the Yucatán Peninsula where this opossum is abundant in the peridomestic habitat, thus bringing a risk to transmit zoonotic diseases such as Chagas disease to the human populations 8 . In this paper, we report for the first time in México data on the infection by Salmonella enterica and the seroprevalence of antibodies against Leptospira interrogans in D. virginiana. This information constitutes a contribution to the knowledge of the epidemiology of zoonotic diseases in México, where in spite the abundance of this mammal in peridomestic habitat, its role in the epidemiology of many zoonotic diseases has not been evaluated.The data of infection by S. enterica and L. interrogans in opossum, were obtained during a populational study of this mammal to evaluate its importance as a reservoir of Trypanosoma cruzi, the etiologic agent of Chagas disease 8 . Opossums were captured from April 1996 to May 1998 in Dzidzilché (21°08'51.76" and 89°41'28.24"), a semiurban small village located 25 km northwestern Mérida, the capital of the Yucatán State, México (Fig. 1). Thorny and low forest, and scarce remains of low deciduous forest characterized the vegetation of the study area. Many abandoned sisal fields doted the surroundings of the village. Fruit trees such as Mangifera inca (mango), Manilkara achras (gumtree), Spondias purpurea (plum), Citrus aurantium (orange), and Carica papaya (papaya), were common in the courtyards. The climate was predominantly warm and humid, with a mean annual temperature of 25.4 °C. During the study period, the rainy season ranged from June to October, and the average annual rainfall was 449 mm.The capture of opossums was carried out following the capture-markingrecapture scheme in a grid of 4 x 4 Tom...

Introducción. Algunos serotipos de Salmonella contienen plásmidos asociados a la virulencia (spv). La presencia de estos plásmidos aumenta la virulencia en ratones infectados experimentalmente, aunque en humanos aún no se ha establecido su papel durante la infección. La mayoría de los estudios realizados hasta la fecha se ha hecho en modelos experimentales, en los cuales las cepas de Salmonella producen septicemia en ratones, pero falla en producir grastroenteritis. Además, son muy pocos los trabajos donde se ha investigado si la presencia de estos plásmidos y/o de los genes codificados en los mismos guardan relación con la presencia de diarrea en humanos. El objetivo del trabajo fue determinar la frecuencia del gen spvB en cepas de Salmonella spp. aisladas de niños y establecer la relación que guarda con la presencia de diarrea en éstos. Materiales y Métodos. Se estudiaron 170 cepas de Salmonella aisladas de niños con diarrea (50) y sin diarrea (120). A todas se les aplicó la técnica de PCR, para amplificar un fragmento de 200 pb que correspondía a la parte central del gen spvB. Resultados. De las 50 cepas de niños con diarrea, 16 fueron positivas a la presencia del gen spvB y 34 negativas. De 120 cepas aisladas de los niños sin diarrea, en 20 se amplificó el gen y en 100 no. De esta forma 36 (21.18%) cepas fueron positivas a la presencia del gen spvB, mientras que 134 (78.82%) fueron negativas (χ2= 4.09509, p = 0.0430). Conclusión. Existe una asociación entre la presencia del gen spvB y la presencia de diarrea en los niños.

Objetivos. Evaluar los conocimientos y actitudes hacia la infección por VIH, e identificar factores de riesgo y la prevalencia de VIH en sexotrabajadoras (ST) en Yucatán, México. Método. De Enero 1998 a Julio 1999, se realizó un estudio longitudinal en una cohorte de 100 ST, que ejercían en Yucatán, México, obteniendo cada 4 meses y en 3 ocasiones diferentes una evaluación clínica, un cuestionario epidemiológico y detección de anticuerpos contra VIH. Resultados. La edad promedio fue de 32 años (18-47). La historia de infecciones de transmisión sexual fue de 45% y de úlceras genitales de 7%. Sólo 16% de las mujeres usaban condón en todas sus relaciones sexuales; 84% de ellas conocían las medidas preventivas, pero solo el 10% había realizado algún cambio de comportamiento efectivo; 92% del grupo reconoció que podría adquirir la infección del VIH por sus prácticas sexuales. La prevalencia de infección por VIH fue nula en la primera evaluación y la incidencia acumulada fue de 1%. Conclusiones. La información acerca del SIDA, las medidas preventivas y cambios en el comportamiento fueron inadecuados en este grupo de estudio. A pesar de la falta de conocimientos y el uso de medidas preventivas para VIH, la prevalencia e incidencia de la infección del VIH (0% y 1%) representan una oportunidad para insistir en campañas preventivas en contra de la infección del VIH en este grupo de ST.

Introducción. Los caldos de enriquecimiento son útiles para la recuperación de Salmonella a partir de portadores, en los cuales el número de microorganismos puede ser tan bajo como 200 UFC/g de heces. En las técnicas de aislamiento de salmonela en microbiología sanitaria, la incubación de los caldos de enriquecimiento a 42°C es utilizada para mejorar la recuperación de la bacteria cuando se encuentra en muy pequeñas cantidades o cuando tiene que aislarse a partir de medios muy contaminados. Material y Métodos. Se estudiaron 2,080 muestras de heces de niños sin diarrea. Se inocularon caldos selenito de sodio y tetrationato de sodio, y ambos se incubaron a 37 y 42°C , y placas de agar XLD para aislamiento directo. Resultados. Ochenta y siete muestras (4.2%) fueron positivas al aislamiento de Salmonellaz spp. Cincuenta y dos muestras (2.5%) fueron positivas con selenito de sodio incubado a 37°C, y 54 (2.6%) a 42°C. El total de muestras positivas con el caldo selenito de sodio fue de 57 (2.7%). Setenta y una muestras (3.4%) fueron positivas con caldo tetrationato de sodio a 37°C y 73 (3.5%) a 42°C. El total de muestras positivas con caldo tetrationato de sodio fue de 76 (3.7%). En la siembra directa en agar XLD se aisló Salmonella en 9 (0.4%) muestras. Discusión. Encontramos que como medio de enriquecimiento el caldo tetrationato de sodio es mejor que el caldo selenito de sodio, y lo recomendamos para el trabajo clínico de rutina. Por otro lado, si es necesario llevar a cabo un estudio epidemiológico para detectar portadores, puede ser útil añadir el caldo selenito de sodio y utilizar dos temperaturas para el aislamiento Salmonella.

Low birth weight is an indicator that allows predicting the probability of survival of a child. In fact, there is an exponential relationship between weight deficit, gestational age, and perinatal mortality. In addition, it is important to indicate that a percentage of term children (37 ≤ weeks of gestation ≤ 41) who have low birth weight present with various sequelae of variable severity –especially in the neurological sphere– and hence the importance of predicting the presentation of low birth weight. Multiple Logistic Regression is one of the most expressive and versatile statistical instruments available for data analysis in both clinical and epidemiology. Its origin dates to the sixties with the transcendent work of Cornfield, Gordon & Smith on the risk of suffering from coronary heart disease and, in the way we know it today, with the contribution of Walter & Duncan in which addresses the issue of estimating the probability of occurrence of a certain event based on several variables. Its use has been universalized and expanded since the early eighties, due to the computer facilities available since then. Quantitative approach. The study design corresponds to that of an analytical observational epidemiological study of cases and controls with directionality response variable→explanatory variables and with prospective temporality. One thousand eight hundred fifteen newborns were studied [178 (9.81%) cases and 1,637 (90.19%) controls], which corresponds to nine controls per case. All term newborns (37 ≤ weeks of gestation ≤ 41) with weights < 2,500 g and ≥ 2,500 g were defined, respectively, as a case and as a control. The values obtained from the β Exponents or Odds Ratios indicate the positive contribution (OR> 1) in ascending numerical order of the explanatory variables alcoholism (0.0018); low socioeconomic level (0.5694); initiation of prenatal care from or after the 20th week of gestation (0.6116); birth interval ≤ 24 months (0.7942); age at menarche ≤ 12 years (1.0792); “unmarried” marital status (1.0961); female gender of the product (1.1271); maternal weight < 50 kg (1.4700); history of abortion(s) (1.5407); number of deliveries = 1 (1.5524); number of prenatal visits ≤ 5 (1.5966); type of delivery or abdominal birth route (1.6169); smoking (2.2019); number of deliveries ≥ 5 (2.2714); maternal age ≤ 19 years (2.4827); maternal age ≥ 36 years (2.8070); pathological obstetric history (4.0735); pathological personal history (4.6475); and maternal height < 150 cm (5.5092).

To determine if the marine foods of animal origin that are sold in establishments in the port of Chabihau, Yucatan, Mexico, represent potential risk factors for the Vibrio alginolyticus species for the development of acute gastroenteritis, wound infection, ear infection and primary septicemia. Three hundred and ninety seafood samples were studied: [298 (76.41%) raw, 8 (2.05%) marinated without heat, 77 (19.74%) partially cooked with heat and 7 (1.79%) completely cooked with heat]. For the homogenization and enrichment of the samples, as well as for the isolation and identification of the Vibrio alginolyticus species, we proceeded according to the methodology described in the eighth edition of the Bacteriological Analytical Manual (FDA). The criteria used in conducting the hypothesis tests for the difference between two percentages was based on the recommendations made by Cochran. The prevalences obtained in raw seafood, marinated without heat, partially cooked with heat and completely cooked with heat were, respectively, 7.72% (23/298), 0.00% (0/8), 7.79% (6/77) and 0.00% (0/7). In 29 (7.44%) samples an equal number of strains were isolated whose biochemical characteristics corresponded to the Vibrio alginolyticus species. It is concluded that raw seafood and partially cooked seafood represent potential risk factors for the Vibrio alginolyticus species for the development of acute gastroenteritis, wound infection, ear infection and primary septicemia.

Objective. To determine if raw seafood, marinated without heat, partially cooked with heat, and completely cooked with heat that are sold for human consumption in establishments in the city of Telchac Puerto, Yucatan, Mexico, represent potential risk factors for the development of acute gastroenteritis, wound infection, primary septicemia and secondary septicemia by Vibrio vulnificus species. Material and methods. Study conducted on a representative sample (n= 132) selected from the total of 200 samples from 38 establishments. From July 1 to December 31, 2019, 132 samples of seafood were studied. Using the Cornfield method, the estimation interval was constructed at the 95% confidence level. Results. In 37 (28.03%) samples an equal number of strains were isolated whose biochemical characteristics corresponded to Vibrio vulnificus. The prevalences obtained in raw marine foods, marinated without heat, partially cooked with heat and completely cooked with heat were 35.59%, 45.45%, 22.45% and 0.00%. The Cornfield estimation interval at the 95% confidence level for Vibrio vulnificus was 13.56% ≤ P ≤ 42.50%. Conclusion. Raw seafood, marinated without heat, and partially cooked with heat represent potential risk factors for Vibrio vulnificus for the development of acute gastroenteritis, wound infection, primary septicemia, and secondary septicemia.