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Striped Bass Skin Disease |
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Written by John Redmond
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Subject: Clarification on Striped Bass Skin Disease
May 3, 2006
MarineFisheries Advisory
UPDATE TO SALTWATERANGLERS ABOUT STRIPED BASS SKIN DISEASE The striped
bass
skindisease reported in a recent Boston Globe article is not a new
disease to fishbiologists and is not considered a serious health risk
by regional publichealth agencies. It is known as Mycobacteriosisand
was first identified on striped bass in Chesapeake Bay in 1997. Fish
that contract this disease develop a bacterial infection that results
in inflammation, tissuedestruction and formation of scar tissue in one
or more organs. While Mycobacteriosis can be transmitted to humans
throughdirect contact with infected fish or water, this disease can be
treated with antibiotics; the bacteria responsible for this disease are
not flesh-eating. Any persons with questions or concerns should
contact a physician.
Myobacteriosisin StripedBass
Signs of
infection in striped bass are first noted in internal organs suchas the
spleen and kidney. Nodules (called granulomas) composed of
inflammatorycells and fibrous connective tissue form in response to the
bacteria in anattempt to stop the infection. An increase in the number
and size of granulomasleads to the formation of extensive scar tissue
and eventual loss of normaltissue architecture. This disease progresses
slowly in fish and has beencharacterized as a “wasting disease” due to
loss of body mass andemaciation. Striped bass may contract the disease
because of weakened healthcaused by poor water quality and
forage-relatedissues in Chesapeake Bay.
Many stripedbass from Chesapeake Bay reside in coastal waters of
Massachusetts betweenMay-October. However, MarineFisherieshas not
received any reports of external lesions and has not observed
anyinternal signs of the disease in fish examined over the last two
years. We are unsure why the disease has not been observed in
Massachusetts, but somescientists suggest that the Chesapeake Bay
migratory stock may be lesssusceptible to disease because they stay
only about two months in the Bay tospawn and have reduced chances of
exposure (most of the fish reported to havethe disease in Chesapeake
Bay are the year-round residents) or the disease iseliminated or
becomes lessened once the fish move into colder, cleaner, oceanwater
and experience better food supplies.
Anglers have inquired if
striped bass that have been “tainted”with Mycobacteriosis are
stilledible. The answer is yes! A recent check of published medical
studies by Maryland Department ofHealth on this kind of infection in
human beings shows that eating properlyprepared and cooked rockfish has
not been associated with human mycobacterial illness. They recommend
that people not consume anyraw striped bass or any fish that appears
diseased. In preparing striped bassfor consumption, common sense
should prevail. Fish with open, reddened lesions on the body or with
signs ofhemorrhage or darkened patches in the fillets should be
discarded. Fish thatappear to be healthy and are properly cooked are
safe to eat. While handlingan infected stripedbass, especially ifthe
skin is cut or scraped, can lead to skin infections, simple
hygieneprecautions can prevent this.
Human MyobacterialIllness Is Treatable
Infections in humans are generally limited to the extremities such as
fingertips and feet, but may involve thejoints, bones and lymph nodes.
Individuals with cuts or scrapes are at higherrisk for infection.The
most frequent symptom is the formation of a persistent bump or nodule
under the skin. Additionalsymptoms may includethe formation of ulcers,
swelling of lymph nodes and joint pain.
When handling any
type offish, use a few practical and simple precautions: 1. wear heavy
gloves and boots to avoid puncturewounds from fish spines; 2.If cuts,
scrapes or other open or inflamed areas of the skin arepresent, cover
hands and wrists with an impermeable barrier (like a rubber orvinyl
glove) to prevent any bacteria from getting into the soft tissue under
the skin where Mycobacterium organisms are known to cause infections;
3. Dispose of any leftover fish parts afterpreparing raw fish; 4.Wash
off all cuttingboards, surfaces, knives and other utensils used to
process raw fish with warm soapywater. (Source:Maryland Department of
Natural Resources.) Again, this disease can be treated with
antibiotics, and any personswith questions or concerns should contact a
physician.
For further information please visit our website at: www.mass.gov/marinefisheries.
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