Changes

If the mycobacteria disseminated from the primary complex then lymph nodes in other regions will also be affected and there will be multiple small foci of infection on other organs.  

If the mycobacteria disseminated from the primary complex then lymph nodes in other regions will also be affected and there will be multiple small foci of infection on other organs.  

==Treatment==

==Treatment==

Treatment is not usually an option due to the chronic nature of the disease, zoonotic potential and test and slaughter policy.  

Treatment is not usually an option due to the chronic nature of the disease, zoonotic potential and test and slaughter policy.  

The mycobacterium reside within macrophages in the lungs where they multiply and result in characteristic [[Lungs Inflammatory - Pathology#Granulomatous pneumonia|granulomatous inflammation]] The regional lymph nodes and also affected  

The mycobacterium reside within macrophages in the lungs where they multiply and result in characteristic [[Lungs Inflammatory - Pathology#Granulomatous pneumonia|granulomatous inflammation]] The regional lymph nodes and also affected  

Microscopically:

Epithelioid cells, with large vesicular nuclei and pale cytoplasm and giant cells, formed by the fusion of macrophages, are found at the centre of tubercles. Surrounding this there is a narrow layer of lymphocytes, mononuclear cells and plasma cells, more advanced cases show peripheral fibroplasia and central necrosis.

**Microscopically:

***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

*This can allow the development of '''miliary tuberculosis''', i.e. numerous small foci of infection in many organs/ tissues

phagocytosed by alveolar macrophages

*phagocytosed by alveolar macrophages

*two processes may develop if the animal has not encountered the organism before:

*two processes may develop if the animal has not encountered the organism before:

:- the organism may grow in the phagocytes as intracellular parasites

:- the organism may grow in the phagocytes as intracellular parasites

::- ultimately, macrophages are killed and infection spreads

::- ultimately, macrophages are killed and infection spreads

:- the organism may be broken down and some antigens taken up by the immune system

:- the organism may be broken down and some antigens taken up by the immune system

::- cell mediated immune system produces cytotoxic T-lymphocytes

cell mediated immune system produces cytotoxic T-lymphocytes which attack and destroy infected cells, leading to a type IV hypesensitivity reaction.

::- T-lymphocytes can attack and destroy cells harbouring bacilli

::- leads to type IV (delayedd type) hypesensitivity

 

the necrosis may erode the wall of a large pulmonary vessel resulting in fatal haemoptysis.

 

[[Category:Cattle]][[Category:To_Do_- lizzyk]]

[[Category:Cattle]][[Category:To_Do_- lizzyk]]

[[Category:Respiratory_Bacterial_Infections]]

[[Category:Respiratory_Bacterial_Infections]]

[[Category:zoonoses]]

[[Category:zoonoses]]