Modelling the Unidentified Abortion Burden from Four Infectious Pathogenic Microorganisms (Leptospira interrogans, Brucella abortus, Brucella ovis, and Chlamydia abortus) in Ewes Based on Artificial Neural Networks Approach: The Epidemiological Basis for a Control Policy.

Unidentified abortion, of which leptospirosis, brucellosis, and ovine enzootic abortion are important factors, is the main cause of disease spread between animals and humans in all agricultural systems in most developing countries. Although there are well-defined risk factors for these diseases, these characteristics do not represent the prevalence of the disease in different regions. This study predicts the unidentified abortion burden from multi-microorganisms in ewes based on an artificial neural networks approach and the GLM. METHODS: A two-stage cluster survey design was conducted to estimate the seroprevalence of abortifacient microorganisms and to identify putative factors of infectious abortion. RESULTS: The overall seroprevalence of Brucella was 70.7%, while Leptospira spp. was 55.2%, C. abortus was 21.9%, and B. ovis was 7.4%. Serological detection with four abortion-causing microorganisms was determined only in 0.87% of sheep sampled. The best GLM is integrated via serological detection of serovar Hardjo and Brucella ovis in animals of the slopes with elevation between 2600 and 2800 meters above sea level from the municipality of Xalatlaco. Other covariates included in the GLM, such as the sheep pen built with materials of metal grids and untreated wood, dirt and concrete floors, bed of straw, and the well water supply were also remained independently associated with infectious abortion. Approximately 80% of those respondents did not wear gloves or masks to prevent the transmission of the abortifacient zoonotic microorganisms. CONCLUSIONS: Sensitizing stakeholders on good agricultural practices could improve public health surveillance. Further studies on the effect of animal-human transmission in such a setting is worthwhile to further support the One Health initiative.

In vitro antimicrobial effect of essential tea tree oil(Melaleuca alternifolia), thymol, and carvacrol on microorganisms isolated from cases of bovine clinical mastitis.

Both Gram-negative and Gram-positive bacteria have recently developed antibiotic resistance to treatments for bovine mastitis, creating a serious concern for public and animal health. The objective of this study was to analyse in vitro microbicidal activity of tea tree oil, thymol and carvacrol (composed of oregano and thyme essential oils) on bacteria isolated from clinical mastitis. Field isolates and ATCC strains of the Staphylococcus spp, Streptococcus spp, Escherichia coli, Klebsiella pneumoniae, and Candida albicans genera were analysed. The agar diffusion technique was used to test bactericidal susceptibility and plate microdilution was utilized to determine the minimum inhibitory, bactericidal, and fractional inhibitory concentrations. Thymol alone and the combinations of thymol-carvacrol and thymol-TTO obtained the highest inhibition diameters for Gram-negative bacteria, while for Gram-positive bacteria and C. albicans, thymol and the combination thymol-carvacrol obtained the highest indices. TTO, thymol, and carvacrol had MIC values of 1.56-25 mg/ml, 0.05-0.4 mg/ml, and 0.02-0.2 mg/ml, respectively. CMB results for the Gram-negative and gram-positive groups were 0.39-0.78 mg/ml, and for C. albicans, 0.78-1.56 mg/ml. Results for the fractional inhibitory concentrations show that the TTO+thymol and thymol+carvacrol combinations had additive activity against groups of Gram-negative bacteria and C. albicans. These natural components, evaluated individually and in combinations, have an effectiveness above 70%.

Epidemiological study of Brucellosis in cattle, immunized with Brucella abortus RB51 vaccine in endemic zones.

In this study the behavior of the Brucella abortus RB51 vaccine was evaluated in bovine herds, with different prevalence of Brucellosis. A prospective longitudinal study was made, in two dairies, one of low prevalence (9%) with 538 cows, and the other of high prevalence (15%) with 612 cows. The cattle were vaccinated twice 90 days apart with RB51 at a dose of 1×10(9)cfu/ml. The monthly incidence was determined during 660 days of observation. In the low prevalence dairy, all positive animals were eliminated as soon as they were diagnosed as positive and in this herd the number of new cases decreased to less than 1% between days 120, and day 660. In the dairy with high prevalence, positive cows were not eliminate resulting in the herd increasing its incidence by the end of the first year. Once positive animals were eliminated the incidence diminishes by day 660 to less of 1%. The odds ratio (OR) in the group of cows with abortion history, in the low prevalence dairy, was of 4.5 (1.2; 16.6), in the dairy ranch with high prevalence it presented an OR of 3.6 (1.5; 8.5). The conclusion from this study was that in brucellosis endemic zones, vaccination with RB51 by itself is not enough to control disease. It is mandatory that the initial elimination of all positive cows at the time of vaccination, the continued elimination of all new positive animals be adhered to for long periods of time.

Prevention of Blackleg by an immunogen of Clostridium chauvoei.

Diseases in livestock caused by Clostridium spp. are of concern in Mexico. There are no good-quality vaccines against these infections, and for this reason several outbreaks have occurred in recent years. The objective of this work was to study the immunogenic capacity of a 156-kDa recombinant protein of Clostridium chauvoei that has shown 80% protection against this disease in guinea pigs. This immunogenic protein was cloned in the expression vector pBluescript and was used to immunize C. chauvoei-free bovine animals that were kept in an endemic area. Three experimental groups were studied. In group 1, 30 bovines were vaccinated by subcutaneous route with one dose of 350 microg/animal of the recombinant protein of 156 kDa. In group 2, 30 bovines were vaccinated with the same concentration of this protein plus aluminium hydroxide as adjuvant. Group 3 was vaccinated with a commercial bacterin by intramuscular route with a dose of 5 mL/animal. In each group, five animals were inoculated with saline solution and remained as controls without vaccination. Blood samples were obtained each month during a 6-month period. Serum samples were analyzed by agglutination test and Western blotting. The recombinant protein of 156 kDa was recognized by serum samples from all the animals in groups 1 and 2. Only two animals from group 3 recognized this protein. During the time of the experiment any cases of this disease were observed. However, other studies with a longer time or greater stress conditions that would favor occurrence of the disease would be required to confirm whether this immunogen is also protective in bovines.

Identificación y tipificación de biotipos y serotipos de Yersinia enterocolitica / Identification and typing of Yersinia enterocolitica biotypes and serotypes isolated

OBJETIVO: Conocer la existencia de Yersinia enterocolitica en suínos visiblemente sanos y sacrificados para el consumo humano. MÉTODOS: Fueron estudiadas 100 muestras de tejido linfático obtenidas en el momento del sacrifício, en un matadero del Estado de México. Fueron realizados muestreos pilotos de 20 casos, de los cuales 20 por cento fueron positivos, permitiendo obtener una muestra estudiada (n=100). Las muestras colectadas de tejido linfático fueron acondicionadas para el aislamiento de Yersinia enterocolitica en caldo de Rappaport y en medio de cultivo de Salmonella-Shigella y MacConkey. Las identificaciones fueron efectuadas por medio de pruebas bioquímicas y serológicas, utilizándose en el caso los antisueros O:3, O:8 y O:9 para la biotipificación correspondiente. RESULTADOS: Fueron obtenidos 22 aislamientos tipificándose 8 serotipos pertenecientes al O:3 y 8 al O:9 correspondientes al biotipo 1; y, en 6 muestras no fue posible la serotipificación. No se encontró en el total de los aislados el serotipo O:8. CONCLUSIONES: En base en la metodología, se registró la presencia de Y. enterocolitica y sus serogrupos en tejido linfático de porcinos por la primera vez en México; esto es importante porque el patógeno y sus serotipos aislados están comprometidos con mayor frecuencia con problemas de salud pública

Evaluación de la prueba de rivanol para el diagnóstico de brucelosis en caprinos / Evaluation of rivanol test for diagnosis of brucellosis in goats

El objetivo del presente trabajo fue evaluar la prueba de rivanol para el diagnóstico de brucelosis caprina, determinando su sensibilidad y especificidad. La prueba se realizó con antígeno comercial de Brucella abortus, utilizando las diluciones 1:25, 1:50, 1:100, 1:200 y 1:400. Para determinar la sensibilidad se utilizaron 64 sueros de caprinos con infección demostrada por aislamiento de B. melitensis, la especificidad se evaluó con 50 sueros de caprinos procedentes de hatos y de zonas libres de brucelosis. La especificidad en cabras vacunadas se obtuvo usando sueros de 22 cabras jóvenes de 3 a 4 meses de edad vacunadas con dosis clásica (1 x 109 ufc/ml) de Rev 1 B. melitensis por vía subcutánea y 59 cabras adultas vacunadas con dosis reducida (1 x 105 ufc/ml) de Rev 1 por vía subcutánea, a partir de los cuales se colectaron muestras serológicas los días 7, 15, 30, 60, 90, 120, 150, 180 y 210 posvacunación. Del grupo de animales infectados 54 sueros resultaron positivos con títulos que variaron de 1:25 a 1:400, resultando la sensibilidad de 83 por ciento. El grupo de caprinos procedentes de zonas libres de brucelosis no presentó ningún resultado positivo, por lo que la especificidad fue del 100 por ciento. El grupo de cabras jóvenes vacunadas con dosis clásica presentó de los 7 a los 90 días 100 por ciento de reactores; a los 120 y 150 días, 27 por ciento; de los 180 a los 240 días, 9 por ciento. Los sueros de cabras vacunadas con dosis reducida reaccionaron 100 por ciento de los 7 a los 90 días; a los 120 y 150 días, 35 por ciento; a los 180 días, 21 por ciento; y a los 210 y 240 días, 6 por ciento de positivos. Se concluye que la prueba de rivanol no ofrece ninguna ventaja para ser utilizada en el diagnóstico de la brucelosis caprina como prueba confirmatoria.

Comparación de pruebas serológicas para el diagnóstico de mastitis por Mycoplasma bovis / Comparison of serological tests for the diagnosis of mastitis by Mycoplasma bovis

El objetivo de este trabajo fue comparar la prueba de hemaglutinación pasiva, inhibición de crecimiento e inhibición de película como métodos para el diagnóstico serológico de mastitis causada por Mycoplasma bovis (Mb). El grupo testigo fue de 40 vacas Holstein sin historia de mastitis por Mycoplasma sp. El grupo problema fue un hato de 57 vacas Holstein. De ambos grupos se obtuvieron muestras de sangre y de leche en condiciones de asepsia. Con el suero sanguíneo se hicieron las pruebas del estudio y se intentó hacer el aislamiento de las muestras de leche. Se obtuvieron 16 aislamientos de Mycoplasma bovis. Se encontró que la prueba de hemaglutinación pasiva tenía 25 por ciento de sensibilidad y una especificidad del 90 por ciento. La prueba de inhibición de crecimiento tuvo una sensibilidad del 62.5 por ciento y especificidad del 95 por ciento. La prueba de inhibición de película presentó una sensibilidad del 100 por ciento y una especificidad del 52.5 por ciento. Se encontró que los títulos de hemaglutinación pasiva en animales infectados se incrementaron hasta 1:160; a diferencia del grupo testigo que llegaron hastas 1:40. En cuanto a la inhibición de crecimiento, los halos fueron de 2 hasta 15 mm en el hato problema y en el grupo testigo, la mayoría no presentó inhibición. Se concluyó que la prueba que mejoro funciona a nivel de hato es la de inhibición de crecimiento