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Created page with '[[Image:Tuberculosis M bovis.jpg|right|thumb|100px|<small><center>Tuberculosis caused by ''M. bovis'' (Image sourced from Bristol Biomed Image Archive with permission)</center></…'
[[Image:Tuberculosis M bovis.jpg|right|thumb|100px|<small><center>Tuberculosis caused by ''M. bovis'' (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
*Caused by ''[[Mycobacterium bovis]]'' and ''M. tuberculosis''
*Reside primarily within macrophages where they multiply and result in characteristic [[Lungs Inflammatory - Pathology#Granulomatous pneumonia|granulomatous inflammation]] (macrophages and giant cells, epithelioid cells)
*Cattle can be infected by inhalation of the organism or through milk
*'''The primary complex'''
**Describes the initial focus of infection at the portal of entry (lungs) plus involvement of regional lymph nodes
**90% of cases exhibit the pulmonary form
**Grossly:
***Small tubercles in dorsocaudal subpleural areas which progress to larger confluent areas of caseous necrosis
***Usually start at bronchio-alveolar junction an progress to the alveoli
***Caseous lesions, may calcify or be encapsulated
***Multiple foci may coalesce
***Ulcers in [[Trachea Inflammatory - Pathology|trachea]] and [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchi]] due to coughed up bacteria
***Spreads into [[Pleural Cavity & Membranes Inflammatory - Pathology|pleura]]
**Microscopically:
***Typical granulomatous inflammation
***Epitheliod and giant cells at centre of tubercles
****Macrophages with ingested bacteria, forming epithelioid cells - large vesicular nuclei, abundant pale cytoplasm
****Giant cells, formed by fusion of macrophages, with multiple nuclei
***Narrow layer of lymphocytes, mononuclear cells and plasma cells at the periphery of the tubercle
***With time, peripheral fibroplasia and central necrosis develop
*If the infection is not contained in the primary complex described above, the mycobacteria can disseminate via lymphatics to other organs and lymph nodes
*This can allow the development of '''miliary tuberculosis''', i.e. numerous small foci of infection in many organs/ tissues
*Caused by ''[[Mycobacterium bovis]]'' and ''M. tuberculosis''
*Reside primarily within macrophages where they multiply and result in characteristic [[Lungs Inflammatory - Pathology#Granulomatous pneumonia|granulomatous inflammation]] (macrophages and giant cells, epithelioid cells)
*Cattle can be infected by inhalation of the organism or through milk
*'''The primary complex'''
**Describes the initial focus of infection at the portal of entry (lungs) plus involvement of regional lymph nodes
**90% of cases exhibit the pulmonary form
**Grossly:
***Small tubercles in dorsocaudal subpleural areas which progress to larger confluent areas of caseous necrosis
***Usually start at bronchio-alveolar junction an progress to the alveoli
***Caseous lesions, may calcify or be encapsulated
***Multiple foci may coalesce
***Ulcers in [[Trachea Inflammatory - Pathology|trachea]] and [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchi]] due to coughed up bacteria
***Spreads into [[Pleural Cavity & Membranes Inflammatory - Pathology|pleura]]
**Microscopically:
***Typical granulomatous inflammation
***Epitheliod and giant cells at centre of tubercles
****Macrophages with ingested bacteria, forming epithelioid cells - large vesicular nuclei, abundant pale cytoplasm
****Giant cells, formed by fusion of macrophages, with multiple nuclei
***Narrow layer of lymphocytes, mononuclear cells and plasma cells at the periphery of the tubercle
***With time, peripheral fibroplasia and central necrosis develop
*If the infection is not contained in the primary complex described above, the mycobacteria can disseminate via lymphatics to other organs and lymph nodes
*This can allow the development of '''miliary tuberculosis''', i.e. numerous small foci of infection in many organs/ tissues