White Spot Disease in Lobster
White spot disease is a serious viral infection affecting many crustaceans, including European lobster. It is caused by a virus called White Spot Syndrome Virus (WSSV). The virus primarily attacks farmed shrimp, but can also infect wild cru...
What is it?
White spot disease is a serious viral infection affecting many crustaceans, including European lobster. It is caused by a virus called White Spot Syndrome Virus (WSSV). The virus primarily attacks farmed shrimp, but can also infect wild crustaceans such as lobster, sometimes without causing visible symptoms in this species. It is considered one of the most feared viral diseases in global crustacean aquaculture, as it can cause very high mortality rates in shrimp farms.
In European lobster, the presence of the virus is mainly studied within health surveillance programs, as this species can act as a virus carrier without necessarily developing the disease in an obvious way.
Key point
This disease is notifiable in many countries because of its major economic impact on crustacean aquaculture; any suspicion must be reported to the relevant health authorities.
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:
In susceptible crustaceans, typical signs are white or whitish spots visible under the shell, particularly on the inner surface of the cephalothorax. Slowed movement, a marked loss of appetite, disorganized or erratic swimming, and unusual behavior such as swimming near the surface or the tank edge are also observed.
In European lobster, infection can remain silent: the animal may carry the virus without showing any of these signs. This is why detection often relies on laboratory testing rather than observation alone.
When signs do appear, they typically develop quite quickly, within a few days.
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 disease is caused by White Spot Syndrome Virus (WSSV), a DNA virus that infects cells in many crustacean tissues, notably those lining the inner surface of the shell, the gills, and certain internal organs.
The virus spreads easily between crustaceans through direct contact, contaminated water, or by consuming already infected animals (cannibalism, molted shells, or carcasses). Significant stress, poor water quality, sudden changes in temperature or salinity, and high animal density in the same tank or holding facility promote the disease and increase its severity.
Transport of live animals, eggs, or larvae between regions, as well as use of contaminated water or equipment, are major pathways for transmission between farms and sometimes into natural environments.
Transmission
The virus spreads between crustaceans through direct contact, contaminated water, ingestion of infected tissue (cannibalism), and contaminated equipment or transport materials. No transmission to humans is known.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Definitive diagnosis relies on specialized laboratory tests, particularly molecular biology tests (PCR) that detect viral genetic material in lobster tissues. Visual examination of white spots under the shell may suggest the diagnosis but is not sufficient on its own, especially in lobsters that may be carriers without visible signs.
These tests are usually performed by veterinary laboratories specializing in pathology of aquatic animals, in coordination with the relevant health authorities.
Treatment
There is no specific antiviral treatment for this disease in crustaceans. Management relies solely on health measures: isolation of suspected animals, improvement of farming conditions, and especially controlled removal of infected individuals to limit virus spread to other animals.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention relies above all on strict biosecurity measures in farming or storage facilities: health screening of introduced animals, quarantine, disinfection of equipment and holding tanks, and rigorous management of water quality.
No vaccine is currently available for this viral disease of crustaceans.
Avoiding introduction of animals from unknown sources or from areas where the virus has already been detected is an essential measure. Compliance with health regulations on transport and importation of live crustaceans also helps limit virus spread.
Possible complications
In sensitive species such as shrimp, the disease can cause mass mortality within days. In European lobster, the main risk is not the clinical disease itself but the role of silent carrier, which can allow the virus to spread to other populations of crustaceans, wild or farmed, with significant economic and ecological impact.
When to see a veterinarian
Observation of unusual white spots under a lobster's shell
Abnormal or clustered mortality in a tank, holding tank, or storage basin
Abnormal behavior: marked lethargy, refusal to eat, disorganized swimming
Suspicion of recently introduced animals from unknown origin in a farming facility or holding tank
Prognosis
The prognosis depends heavily on the species and context. In farmed shrimp, the declared disease is often associated with very high and rapid mortality. In European lobster, infection may remain asymptomatic, with individual prognosis generally better, but the main concern remains transmission of the virus to other susceptible populations.
Frequently asked questions
Can you eat a lobster that has white spot disease?
This virus is not known to be dangerous to humans. However, a sick or unusually dead animal should never be consumed, as a matter of general health precaution and because of the risk of other meat spoilage.
Does the European lobster often fall ill with this disease?
He may be infected with the virus without developing visible symptoms. He then acts mainly as a carrier, which poses a risk for virus transmission rather than a direct risk to his own health.
Is there a treatment to cure an infected lobster?
No, there is no specific antiviral treatment. Management relies on prevention, surveillance, and controlled culling of infected animals in livestock.
How can a farm protect itself from this disease?
By implementing strict biosecurity measures: health screening of introduced animals, quarantine, equipment disinfection, and regular monitoring of animal health and water quality.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 27 August 2026
Comments (0)
No comments yet.
AT A GLANCE
Need a veterinarian?
Find a practitioner near you on TunisieVet, with their specialities, hours and contact details.
Find a veterinarianCategories
Affected species
This information is provided for educational purposes only and is not a substitute for a veterinary consultation. If you have any concerns about your animal's health, consult a veterinarian.
Thinking of welcoming a pet? Dogs and cats are waiting for a family in Tunisia, and adoption is completely free.
Adoption listingsTo discover
Related diseases and linked Animalia content.
Bacterial infection in lobsters (Vibrio and Aeromonas)
Bacterial
Parasitism by copepods and fish lice in lobsters
Parasitic
Abnormal molting and dysecdysis in lobster
Environmental
Be among the first to use our app. Sign up and get early Google Play access.
Discover
