Provides information about fish tuberculosis disease.

1. MYCOBACTERIOSIS OR FISH
TUBERCULOSIS
PHIBI PHILIP N
BFT1326
AQUACLINICS

3. MYCOBACTERIUM SPP.
• Gram – positive, aerobic.
• Acid – fast bacteria & hence won’t stain well (mycolic
acid).
• Non-motile.
• 1.5–2.0 × 0.25–0.35 μm in size.
• M. marinum, M. fortuitum, and M. chelonae.
• They are found worldwide in bodies of fresh water,
brackish water and salt water.
• They produce pale-cream to yellow/orange colonies on
Source:

4. ENVIRONMENTAL CONDITIONS FAVOURING
MYCOBACTERIA
• Low levels of dissolved oxygen.
• Low pH (4-6).
• High organic loads.
• Warm water (27°C-38C°).

5. Source: Noha fish disease

6. CLINICAL SIGNS OF MYCOBACTERIOSIS:
• Slow progression of the disease - younger fish infected with
Mycobacteriosis - no external signs.
• Nonhealing, shallow to deep skin ulcers.
• Hyperpigmentation.
• Corneal ulcers.
• Pale coloration.
• Emaciation.
• White nodules on viscera.
Source: Noga fish disease
diagnosis book

7. CONT…
• Internally, 1 – 4 mm white nodules may be present on
the viscera, especially hypertrophic kidney or spleen.
• When the nodules develop in the organs, edema (excess
fluid accumulation) may develop, as well as peritonitis
(inflammation of the body cavity).
Source: Noga fish disease

8. EPIDEMIOLOGY
Host range:
• Virtually all freshwater and marine aquarium fish are probably
susceptible, especially members of the freshwater families
anabantidae, characidae, and cyprinidae. Almost 150 species of
fish have been affected.
• It has recently become a serious problem in laboratory research
facilities that maintain medaka/Japanese killifish (Oryzias latipes)
and zebrafish (Danio rerio).
• Mycobacteriosis has also recently become a serious problem in
several species of cultured food fish such as European sea bass

9. TRANSMISSION
• Shedding of bacteria from infected skin ulcers, as well as
the intestine, is the major source of contagion.
• Ingestion is probably the major source of infection
including fish that have recently eaten dead tank mates.
• The bacteria can survive for 2 years in the environment.
• Transovarian transmission has been demonstrated in
some fish, such as platy but does not occur in salmonids.

10. TRANSMISSION – A CASE
• Another possible concern in terms of novel host – endemic
pathogens might be much more pathogenic to exotic fish that are
imported into a region for culture - An exotic fish species may be
inherently more susceptible to an endemic pathogen that it has
not previously encountered in nature - the exotic host may act as
a major reservoir for that pathogen - amplification of that
pathogen’s abundance in the environment - epidemic disease in
native populations.
• This has been suspected to be one possible reason for the
epidemic prevalence of Mycobacteriosis in native red sea fish

11. HUMAN HEALTH CONCERNS
• Although transmission from infected fish to humans is
rare, it is important to be aware of the potential
occurrence
• Mycobacterium spp. that cause disease in fish
occasionally cause a skin infection in people that is
referred to as “fish handler's disease" or "fish tank
granuloma”.
Source: Google images

12. HISTOPATHOLOGY
• Chronic inflammatory response with epithelioid macrophages
surrounding the bacteria.
• Lesions often have necrotic centres and may have
melanomacrophages or melanocytes.
• Bacteria are typically located in the centre of the inflammatory
focus.

13. DIAGNOSIS
• Presence of large numbers of granulomas in wet mounts especially
spleen and kidney.
• Isolation on middlebrook 7H10 agar allows definitive diagnosis by
biochemical identification, as well as determination of the species
involved.
• Mixed infections involving up to several mycobacterium species
have been observed in some cases and the relative importance of
each species to the clinical signs and disease is usually not entirely
clear.
Source: Noga fish disease
diagnosis book
Source: Noga fish disease
diagnosis book

14. TREATMENT
• This disease is insidious and difficult to eradicate. Even
freezing does not kill bacteria in carcasses.
• In one study, erythromycin, rifampicin, or streptomycin
was effective against experimental infections.
• Kanamycin is effective in reducing clinical disease (no
eradication).
• Disinfection is the best method (sodium hypochlorite,
lysol, 50% ethanol, sodium chlorite).

15. TREATMENT
• Although there are no vaccines commercially available
against fish pathogenic Mycobacteria, it is recognised that
there is a cell-mediated response in fish, i.e. in Rainbow
trout.
• A DNA vaccine involving the AG85A gene encoding for
one of the major secreted fibronectin binding proteins of
M. marinum and cloned in a eukaryotic expression vector
stimulated a protective (120 days after vaccination)

16. REFERENCES
• EDWARD J NOGA. 2010. FISH DISEASE, DIAGNOSE & TREATMENT (II
EDITION ). WILEY-BLACKWELL. 226-227.
• RUTH FRANCIS-FLOYD & ROY YANONG. 2012. MYCOBACTERIOSIS
IN FISH. UNIVERSITY OF FLORIDA, IFAS.
• BRIAN AUSTIN & DAWN A. AUSTIN. 2012. BACTERIAL FISH
PATHOGENS: DISEASE OF FARMED AND WILD FISH (V EDITION).
SPRINGER. 122-126.