Changes

Organisms penetrate the M-cells of the [[Peyer's Patches - Anatomy & Physiology|Peyer's patches]].  

Organisms penetrate the M-cells of the [[Peyer's Patches - Anatomy & Physiology|Peyer's patches]].  

Mycobacteria invade macrophages and cause a granulomatous inflammatory response.

Mycobacteria invade macrophages and cause a granulomatous inflammatory response.

Death may result from:  

Death may result from: damage to the mucosa, not absorbing nutrients, or inflammatory loss of protein.

** Damage to the mucosa.

** Inflammatory loss of protein

The infected host appears emaciated.

The infected host appears emaciated.

*** Fat is pale and oedematous, and there is not much of it.   

Fat is pale and oedematous, and only present in small amounts.   

* Signs are confined to the terminal [[Small Intestine - Anatomy & Physiology|small intestine]] (especially the [[Ileum - Anatomy & Physiology|ileum]]) but are characteristic.  

Signs are confined to the terminal [[Small Intestine - Anatomy & Physiology|small intestine]] (especially the [[Ileum - Anatomy & Physiology|ileum]]) but are characteristic. It has diffusely thickened, velvety mucosa surface and transverse, corrugated ruggae with reddened crests. Infected animals may also have enlarged mesenteric lymph nodes

** Diffusely thickened mucosa

 

*** Transverse, corrugated ruggae with reddened crests.

[[Image:johnes disease proliferative ileitis.jpg|thumb|right|150px|Proliferative ileitis in Johnes disease (Courtesy of Bristol BioMed Image Archive)]]

Changes are milder in sheep and goats, than seen in cows, and is symptoms are often missed.

*** Mucosa may take on a 'corn-on-the-cob' appearance in advanced cases.[[Image:johnes disease proliferative ileitis.jpg|thumb|right|150px|Proliferative ileitis in Johnes disease (Courtesy of Bristol BioMed Image Archive)]]

* Changes are milder in sheep and goats.

** May produce small areas of necrosis not usually seen in cattle.

** Sheep may get a pigmented form.

====Histologically====

====Histologically====

[[Image:johnes disease histological.jpg|thumb|right|150px|Histological appearance of Johnes disease (Courtesy of Bristol BioMed Image Archive)]]

[[Image:johnes disease histological.jpg|thumb|right|150px|Histological appearance of Johnes disease (Courtesy of Bristol BioMed Image Archive)]]

* Many large macrophages (epithelioid macrophages) in mucosa, submucosa and lymph nodes.

 

** Mesenteric lymph nodes are pale and enlarged (though not necrotic). 

There are many large macrophages (epithelioid macrophages) in mucosa, submucosa and lymph nodes.

* The lamina propria is infiltrated by sheets of macrophages with some lymphocytes.

The mesenteric lymph nodes are pale and enlarged (though not necrotic), and the lamina propria is infiltrated by sheets of macrophages with some lymphocytes.

* Acid-fast bacteria are found in the macrophages and giant cells.

Acid-fast bacteria are found in the macrophages and giant cells, and this is detected by Ziehl-Neelson stain.  

** Detected by Ziehl-Neelson stain.  

 

** Bacteria act like foreign body producing a type IV hypersensitivity reaction.

Bacteria act like foreign bodies producing a type IV hypersensitivity reaction.

* Sheep have two different forms.

Sheep have two different forms:

*# '''Paucibacillary'''

1. '''Paucibacillary'''; many T cells, and few bacilli.

*#* Many T cells

 

2.  '''Multibacillary''': Many macrophages, many bacilli in macrophages, and few lymphocytes.

*# '''Multibacillary'''

*#* Many macrophages

*#* Many bacilli in macrophages

*#* Few lymphocytes

===Diagnosis===

===Diagnosis===

* Diagnosis is by

Diagnosis is by; Histology, Serological tests, [[ELISA]] and AGID.

** Histology

 

** Serological tests

60% of cases have lesions in [[Colon - Anatomy & Physiology|colon]] and [[Rectum - Anatomy & Physiology|rectum]] and can be diagnosed by rectal biopsy.

*** ELISA & AGID

 

[[Category:Enteritis,_Bacterial]][[Category:Enteritis, Proliferative]][[Category:Cattle]]

** 60% of cases have lesions in [[Colon - Anatomy & Physiology|colon]] and [[Rectum - Anatomy & Physiology|rectum]] and can be diagnosed by rectal biopsy.[[Category:Enteritis,_Bacterial]][[Category:Enteritis, Proliferative]][[Category:Cattle]]

[[Category:Enteritis,_Granulomatous]]

[[Category:Enteritis,_Granulomatous]]

[[Category:To_Do_-_Clinical]]

[[Category:To_Do_-_Clinical]]

[[Category:To_Do_-_Max]]

[[Category:To_Do_-_Max]]