Changes

==Epidemiology==

==Epidemiology==

Fish may be infected by ingesting feed and water contaminated with faecal material, urine or exudates from diseased animals that contain mycobacteria (Ross and Johnson, 1962) Ross AJ, Johnson HE, 1962. Studies of transmission of mycobacterial infections of chinook salmon. Progressive Fish Culturist, 24:147-149. The identification of Mycobacteria and acid-fast bacteria in piscine ova and tubercle granulomas in ovarys of different species suggests that transovarian transmission may be a possibility.

Fish may be '''infected by ingesting feed and water contaminated with faecal material, urine or exudates from diseased animals''' that contain mycobacteria (Ross and Johnson, 1962) Ross AJ, Johnson HE, 1962. Studies of transmission of mycobacterial infections of chinook salmon. Progressive Fish Culturist, 24:147-149. The identification of Mycobacteria and acid-fast bacteria in piscine ova and tubercle granulomas in ovarys of different species suggests that transovarian transmission may be a possibility.

Mycobacteriosis can be sub divided into subacute and chronic forms and once fish are infected, mycobacteria spread via the circulatory or lymphatic system to other organs such as the spleen, kidney and liver.  Both hard and soft granulomas are formed in the chronic proliferative form and in severe cases larger granulomas form within visceral organs and loose connective tissues.  Mycobacterium has many vectors including crustaceans and molluscs.

Mycobacteriosis can be '''sub divided''' into '''subacute''' and '''chronic forms''' and once fish are infected, mycobacteria spread via the circulatory or lymphatic system to other organs such as the '''spleen, kidney and liver'''.  Both hard and soft granulomas are formed in the chronic proliferative form and in severe cases larger granulomas form within visceral organs and loose connective tissues.  Mycobacterium has many '''vectors''' including '''crustaceans and molluscs'''.

 

==Distribution==

==Distribution==

Worldwide - mycobacterium is ubiquitous in the water and sediment. It has been documented in fish from the Atlantic and Pacific Sea, Asia, Africa, North America, Australia, South America and Europe.

'''Worldwide''' - mycobacterium is '''ubiquitous in the water and sediment'''. It has been documented in fish from the Atlantic and Pacific Sea, Asia, Africa, North America, Australia, South America and Europe.

 

==Pathology==

==Pathology==

Pathology includes necrotised and enlarged spleen, kidney and liver with diffuse greyish-white nodules, cysts (white spheres) within the body cavity and muscle, fusion of visceral membranes and increased peritoneal fluid.

Pathology includes '''necrotised and enlarged spleen, kidney and liver''' with '''diffuse greyish-white nodules''', cysts (white spheres) within the body cavity and muscle, fusion of visceral membranes and increased peritoneal fluid.

Histopathology of granulomas varies for subacute and chronic forms.  Sub acute forms have a large caseous necrotic areas with surrounding diffuse reticuloendothelial cells and macrophages.  Acid-fast bacilli can be found within the reticuloendothelial cells and within the cytoplasm of phagocytic macrophages. Whereas the chronic proliferative form is characterized by soft granulomas with four distinguishable layers; a central caseous necrosis, (with or without nuclear debris), spindle-shaped epithelioid cells, eosinophilic, flattened, epithelioid cells and then a fine fibrous connective tissue encircling to form a thin capsule. Hard granulomas can also been seen with chronic forms and are composed of epithelioid cells encapsulated by fibrous connective tissue with or without calcification.  

 

Histopathology of granulomas varies for subacute and chronic forms.  '''Sub acute forms''' have a '''large caseous necrotic areas''' with '''surrounding diffuse reticuloendothelial cells and macrophages'''.  Acid-fast bacilli can be found within the reticuloendothelial cells and within the cytoplasm of phagocytic macrophages. Whereas the '''chronic proliferative form''' is characterized by '''soft granulomas with four distinguishable layers'''; a '''central caseous necrosis''', (with or without nuclear debris), '''spindle-shaped epithelioid cells''', '''eosinophilic, flattened, epithelioid cells''' and then a '''fine fibrous connective tissue''' encircling to form a thin capsule. '''Hard granulomas''' can also been seen with '''chronic forms''' and are composed of '''epithelioid cells encapsulated by fibrous connective tissue with or without calcification'''.  

Infected crustaceans show melanised lesions in muscle, cuticle, ovary, gill and heart.

Infected crustaceans show melanised lesions in muscle, cuticle, ovary, gill and heart.

==Diagnosis==

==Diagnosis==

Mycobacteriosis can be confirmed by PCR, DNA probes- in situ hybridisation and antibodies-based methods and presumptive diagnosis can  be made from  clinical signs, bacteriology and histopathology.

Mycobacteriosis can be '''confirmed''' by '''PCR, DNA probes- in situ hybridisation and antibodies-based methods''' and presumptive diagnosis can  be made from  clinical signs, bacteriology and histopathology.

 

==Treatment==

==Treatment==

Tetracycline and kanamycin sulphate can be used to treat mycobactriosis and experimentally cotrimoxazole, cycoserine, ethambutol, isoniazid, rifampacin and streptomycin have been used.

'''Tetracycline and kanamycin sulphate''' can be used to treat mycobactriosis and experimentally cotrimoxazole, cycoserine, ethambutol, isoniazid, rifampacin and streptomycin have been used.

==References==

==References==