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Mycobacterium bovis is the main cause of bovine tuberculosis (BTB) in cattle and can also infect humans. Zebu cattle are considered more resistant to some infectious diseases compared with Holstein-Friesian (HF) cattle, including BTB. However, epidemiological studies may not take into account usage differences of the two types of cattle. HF cattle may suffer greater metabolic stress due to their more or less exclusive dairy use, whereas Zebu cattle are mainly used for beef production. In experiments conducted so far, the number of animals has been too small to draw statistically robust conclusions on the resistance differences between these cattle breeds. Here, we used a BCG challenge model to compare the ability of naïve and vaccinated Zebu and HF cattle to control/kill mycobacteria. Young cattle of both breeds with similar ages were housed in the same accommodation for the duration of the experiment. After correcting for multiple comparisons, we found no difference between naïve HF and Zebu (ρ = 0.862) cattle. However, there was a trend for vaccinated HF cattle to have lower cfu numbers than non-vaccinated HF cattle (ρ = 0.057); no such trend was observed between vaccinated and non-vaccinated Zebu cattle (ρ = 0.560). Evaluation of antigen-specific IFNγ secretion by PBMC indicated that Zebu and HF cattle differed in their response to mycobacteria. Thus, whilst there may be difference in immune responses, our data indicate that with the number of animals included in the study and under the conditions used in this work, we were unable to measure any differences between Zebu and HF cattle in the overall control of mycobacteria. Whilst determination of different susceptibilities between Zebu and HF cattle using the BCG challenge model will require larger numbers of animals than the number of animals used in this experiment, these data should inform future experiments.

Background Bovine tuberculosis is a chronic inflammatory disease that causes granuloma formation mainly in retropharyngeal, tracheobronchial, mediastinal lymph nodes and lungs of bovines. The presence of these lesions in other tissues such as the eyeball is very rare and difficult to diagnose. This study describes macroscopic and microscopic pathological findings in a calf with ocular and meningeal tuberculosis. Case presentation March 2019, an eight-month-old Holstein Friesian calf was identified in a dairy farm located in central Mexico with a clinical cough, anorexia, incoordination, corneal opacity and vision loss. At necropsy, pneumonia, lymphadenitis, meningitis, and granulomatous iridocyclitis were observed. The histopathological examination revealed granulomatous lesions in lung tissue, lymph nodes, meninges and eyes with the presence of acid-fast bacilli associated with Mycobacterium spp. Conclusion To the best of our knowledge, this is the first report that describes macroscopic and microscopic pathological findings of ocular tuberculosis in cattle. This report highlights the importance of considering bovine tuberculosis in the differential diagnosis of corneal opacity and loss of vision in cattle.

Bovine tuberculosis is a chronic inflammatory disease that causes granuloma formation. Characterization of granulomatous lesions of Mycobacterium bovis (M. bovis) experimentally infected cattle has helped to better understand the pathogenesis of this disease. However, few studies have described granulomas found in M. bovis naturally infected cattle. The aim of this work was to examine granulomas from Holstein-Friesian cattle naturally infected with M. bovis from a dairy basin located in the central region of Mexico. Tissue samples from thirty-two cattle with lesions suggestive of tuberculosis were collected post-mortem. Fifteen of the 32 sampled animals (46.8%) were 4 months of age or younger (calves), whereas the rest (53.2%, 17/32) were over one year old (adults). Macroscopic lesions suggestive of tuberculosis were found in the mediastinal lymph node chain of all animals (32/32). From the 1,143 granulomatous lesions that were microscopically analyzed, 34.6% (396/1143) were collected from adult animals and subsequently classified according to the nomenclature suggested by Wangoo et al., 2005. Surprisingly, lesions from calf tissues showed an atypical pattern which could not be fitted into the established developmental stages of this classification. Granulomatous lesions found in calves covered most of the affected organ, histologically showed large necrotic areas with central calcification, absence of a connective tissue capsule, and few giant cells. Also, there was a higher percentage of lesions with acid-fast bacilli (AFB) when compared to studied granulomas in adults. Growth of Mycobacterium spp was detected in 11 bacteriological tissue cultures. Genotypic identification of M. bovis was performed by DNA extraction from bacterial isolates, formalin-fixed and paraffin-embedded (FFPE) tissues and samples without bacterial isolation. M. bovis was detected by PCR in 84.3% (27/32) of the studied cases; whereas other AFB were observed in tissues of the remaining sampled animals (5/32). Our results describe atypical granuloma formation in calves 4 months of age or younger, naturally infected with M. bovis. These findings contribute to better understanding the physiopathology of M. bovis infection in cattle.

Veterinaria Mexico OA ISSN: 2448-6760 Cite this as: Carrisoza Urbina J, Flores Velazquez E, Gutierrez Reyes JA, Juarez Lopez NO. Assessment of the degree of concordance between the results of histopathological examination and bacterial culture in the diagnosis of bovine tuberculosis in Mexico. Veterinaria Mexico OA. 2015;2(3). doi: 10.21753/vmoa.2.3.348 . Bovine tuberculosis is a complex disease that is difficult to diagnose, control and eradicate and negatively impacts many farms. The objective of this study was to assess the degree of concordance between the results of histopathological examination and bacterial culture in the diagnosis of bovine tuberculosis lesions obtained in the laboratories certified by the Secretaria de Agricultura, Ganaderia, Desarrollo Rural, Pesca y Alimentacion (Ministry of Agriculture, Animal Production, Rural Development, Fisheries and Feeding) at the national level between January 2009 and December 2012 in Mexico. Tissue samples (10,818) from regular slaughter cattle that did not have tuberculin tests but had lesions suspected of having been caused by tuberculosis were sent to 10 authorized laboratories. Using Cohen’s kappa to measure the reliability of the diagnosis, a general concordance was obtained between the histopathological examination and bacterial culture results with a kappa of 0.634 and a 95% (0.618 – 0.650) confidence interval (CI), which shows good concordance between the two techniques at the national level. The laboratory in Chihuahua had the highest kappa [k=0.784, 95% CI (0.754–0.814)] and the laboratory of the La Laguna Region in the state of Coahuila had a low value of global concordance [k= 0.334, 95% CI (0.257–0.412)]. The number of positive samples in bacterial culture was low in Tamaulipas (21 samples), Sonora (41 samples), and Yucatan (45 samples) because tuberculosis prevalence in those states is ≤ 0.04%. The number of positive samples in bacterial culture was low in Tamaulipas (21 samples), Sonora (41 samples), and Yucatan (45 samples) because tuberculosis prevalence in those states is ≤ 0.04%. The reason for the disagreement between the two tests among some laboratories includes factors such as a lack of economic resources, infrastructure or personnel training. Correct sampling procedures, storage facilities, and shipping and sample processes are important in optimizing the bacteriological and histopathological results and obtaining correct diagnoses and differential diagnoses of bovine tuberculosis.

"La tuberculosis bovina es una enfermedad compleja, difícil de diagnosticar, controlar y erradicar y tiene un impacto negativo en el sector ganadero. El objetivo de este estudio fue evaluar el grado de concordancia entre los resultados del examen histopatológico y del cultivo bacteriológico en el diagnóstico de lesiones de tuberculosis bovina realizado en los laboratorios certificados por la Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación (sagarpa) a nivel nacional, en el periodo comprendido entre enero de 2009 y diciembre de 2012 en México. La información se obtuvo de 10,818 muestras de bovinos de matanza regular, a las cuales no se los sometió a la prueba de tuberculina, pero tenían lesiones que sugerían tuberculosis. Esas muestras se enviaron a diez laboratorios autorizados. Mediante el coeficiente kappa de Cohen, se midió la confiabilidad del diagnóstico; se obtuvo una concordancia general entre los resultados del examen histopatológico y del cultivo bacteriológico de k= 0.633, con un intervalo de confianza (IC) del 95% (0.618–0.649), lo cual indica una concordancia buena entre las dos pruebas a nivel nacional. El laboratorio de Chihuahua obtuvo el valor más alto de kappa [k = 0.784; IC del 95% (0.754–0.814)] y el laboratorio de la Región Lagunera en el estado de Coahuila obtuvo un valor bajo de concordancia [k = 0.334; IC del 95% (0.257–0.412)]. El número de muestras positivas en el cultivo bacteriológico fue bajo en Tamaulipas (21 muestras), Sonora (41 muestras) y Yucatán (45 muestras), ya que la prevalencia de tuberculosis en esos Estados es ≤ 0.04%. El grado de discordancia en algunos laboratorios involucra factores como la falta de recursos económicos, de infraestructura y de capacitación. El procedimiento correcto para la toma, conservación, envío y procesamiento de las muestras es crucial para optimizar los resultados bacteriológicos e histopatológicos y, así, llegar al correcto diagnóstico de la tuberculosis bovina y de diagnósticos diferenciales."