Bacterial Skin Infection in the Great White Shark
Bacterial skin infection in the great white shark is a skin condition caused by the overgrowth of opportunistic bacteria, usually following a wound. Like other cartilaginous fish, this shark has skin covered with dermal denticles that norma...
What is it?
Bacterial skin infection in the great white shark is a skin condition caused by the overgrowth of opportunistic bacteria, usually following a wound. Like other cartilaginous fish, this shark has skin covered with dermal denticles that normally provide good protection against external damage. When this barrier is breached, bacteria naturally present in seawater or on the animal itself can multiply and cause local inflammation, sometimes spreading more widely.
This condition is very poorly documented in this wild species and difficult to observe, because the great white shark lives in the open ocean and is rarely examined closely by a veterinarian. Most knowledge comes from observations of injured individuals in their natural habitat, cases in public aquariums, or extrapolation from other shark and fish species.
Key point
An untreated skin infection can progress to severe generalized infection, particularly in an animal that is already weakened.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Damaged skin areas are observed: redness, swelling, wounds that do not heal normally, sometimes with a whitish or blackish appearance around the lesion.
The skin may appear eroded or show irregular crusting.
An inflammatory halo or slight swelling may develop around an old wound (bite from another shark, fishing injury, rubbing against an object).
In more advanced cases, the animal may display unusual behavior, slower swimming, or loss of appetite, indirect signs of general malaise.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The infection results from the overgrowth of opportunistic marine bacteria (for example, species of Vibrio or other common marine bacteria) at the site of a skin breach. These bacteria take advantage of a wound, a bite received during aggressive interaction with another shark, a fishing injury (hook, net), or rubbing against an abrasive surface to colonize the tissues.
Traumatic wounds (bites, hooks, nets, collisions) are the main risk factor.
A weakened immune system from stress, poor water quality (in captivity), or malnutrition can promote infection establishment.
Young individuals and weakened animals appear more vulnerable.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Diagnosis in the wild is extremely difficult. It relies on visual observation of lesions by divers, researchers, or during tagging operations. In captivity, a veterinarian specializing in aquatic animals can take a sample from the lesion to identify the causative bacterium and assess the extent of infection.
Treatment
In captivity, treatment may include antibiotics appropriate for marine wildlife, administered under strict specialized veterinary supervision, as well as local wound care. In the wild, treatment is generally not possible; the outcome depends on the animal's own healing capacity.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
In the wild, prevention relies mainly on reducing dangerous human interactions (fewer accidental captures, careful handling during scientific tagging programs).
In captivity, maintaining excellent water quality, providing adequate space to minimize collisions and conflicts, and regular veterinary monitoring help reduce the risk.
Possible complications
An uncontrolled infection can spread into deeper tissues, reach muscle tissue, and lead to septicemia (generalized infection), potentially fatal.
Abnormal scarring can also permanently weaken the affected area.
When to see a veterinarian
A wound that does not appear to be healing after several weeks
Swelling, marked redness, or unusual odor around a lesion
Change in behavior (lethargy, loss of appetite) in captivity
Any major wound noted during scientific handling or at a care facility
Prognosis
The prognosis depends on how severe and extensive the wound is. A small shallow wound may heal on its own thanks to the shark's skin regeneration abilities. However, a deep or widespread infection remains concerning, especially in the wild where no treatment is possible.
Frequently asked questions
Can a great white shark heal on its own from a skin infection?
Yes, in many cases, a superficial wound can heal naturally thanks to the excellent regenerative capacities of shark skin, provided that infection does not take hold deeply.
Is this disease dangerous for humans?
No, this is not a disease transmissible to humans. The main risk for humans remains related to handling the animal itself, not to bacterial infection.
How do scientists detect these infections at sea?
They are generally spotted through visual observation, during dives, underwater photography, or scientific tagging operations, without the possibility of thorough examination.
Is there a vaccine against this infection?
No, there is no vaccine for this condition in the great white shark.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 29 August 2026
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