Difference between revisions of "Tuberculosis - Cattle"

From WikiVet English
Jump to navigation Jump to search
(Redirected page to Mycobacterium bovis)
 
(35 intermediate revisions by 2 users not shown)
Line 1: Line 1:
[[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>]]
+
#redirect[[Mycobacterium bovis]]
 
 
 
==Description==
 
A chronic disease caused by ''[[Mycobacterium bovis]]'' and ''M. tuberculosis'' 
 
 
 
==Signalment==
 
 
 
==Diagnosis==
 
 
 
===Clinical Signs===
 
 
 
===Laboratory Tests===
 
 
 
===Radiography===
 
 
 
===Pathology===
 
 
 
==Treatment==
 
 
 
==Prognosis==
 
 
 
==References==
 
 
 
 
 
 
 
*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
 
 
 
 
 
 
 
 
 
*inhalation of ''Mycobacterium bovis'' most common via droplets
 
*some tubercle bacilli enter the lymph and travel to the bronchial or mediastinal nodes
 
*inhaled bacilli reach the alveoli, set up a focus of inflammation
 
*phagocytosed by alveolar macrophages
 
*two processes may develop if the animal has not encountered the organism before:
 
:- the organism may grow in the phagocytes as intracellular parasites
 
::- produces a nodule of parasitised swollen macrophages known as a tuburculous nodule or a tubercle granuloma
 
::- ultimately, macrophages are killed and infection spreads
 
:- the organism may be broken down and some antigens taken up by the immune system
 
::- cell mediated immune system produces cytotoxic T-lymphocytes
 
::- T-lymphocytes can attack and destroy cells harbouring bacilli
 
::- leads to type IV (delayedd type) hypesensitivity
 
::- 'caseous' or cheesy type of necrosis
 
::- if bacterium destroyed, further infection/disease is prevented
 
 
 
====Sequelae====
 
*chronicity
 
=====Tuberculosis pleurisy=====
 
*caseous lymph node ruptures
 
*results from extensive tissue necrosis
 
:- if located in lung alveoli, the follicle may rupture into a bronchus, causing spread of the disease to all the other lobules served by that bronchus
 
:- if the ensuing necrosis erodes the wall of a large pulmonary vessel, this ruptures into the lung and a fatal haemoptysis might follow
 
 
 
 
 
[[Category:Cattle]][[Category:To_Do_- lizzyk]]
 
[[Category:Respiratory_Bacterial_Infections]]
 

Latest revision as of 10:24, 18 October 2010