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Diseases of crustaceans

Viral diseases—White spot disease

white spot disease

White spot disease in giant black tiger prawn (Penaeus monodon). Prawns at top and right of main photo show pink body colour typical of acute phase of infection. Those at bottom and to left show classic white spots following acute phase

Source: DV Lightner

CLICK ON IMAGE TO ENLARGE white spot disease

White spot disease in giant black tiger prawn, showing classic white spots on carapace

Source: DV Lightner

Signs of disease

Important: animals with disease may show one or more of the signs below, but disease may still be present in the absence of any signs.

Disease signs at the farm level
Disease signs at the tank and pond level
Clinical signs of disease in an infected animal

The shell lesions range from minute spots to discs several millimetres in diameter, and may coalesce into larger plates. They are most easily observed by removing the cuticle over the cephalothorax, scraping away any attached tissue with the thumbnail and holding the cuticle up to the light.

White spots in the cuticle are unreliable even for preliminary diagnosis of white spot disease, because similar spots can be produced by some bacteria, high alkalinity and other infectious or environmental conditions.

Disease agent

The causative agent of white spot disease is white spot syndrome virus, a large DNA virus assigned to the new genus Whispovirus (family Nimaviridae). The virus infects only crustaceans and appears not to be related to any other known viruses. It is not involved in the parasitic disease, common in finfish, also known as white spot.

Host range

All decapod crustaceans (order Decapoda), including prawns, lobsters and crabs from marine, brackish or freshwater environments, are considered susceptible to infection. However, the disease has mainly been a problem in farmed penaeid (family Penaeidae) prawns.

Crustaceans known to be susceptible white spot syndrome virus:
black tiger prawn* (Penaeus monodon)
Chinese white shrimp* (Penaeus chinensis)
Gulf banana prawn* (Penaeus merguiensis)
Indian banana prawn* (Penaeus indicus)
Kuruma prawn* (Penaeus japonicus)
Pacific white shrimp* (Penaeus vannamei)
red claw freshwater crayfish* (Cherax quadricarinatus)
blue shrimp (Penaeus stylirostris)
green tiger prawn (Penaeus semisulcatus)

White spot syndrome virus also occurs naturally in many other decapods, including:
mud crabs* (Scylla serrata, Charybdis feriatus, Portunus pelagicus, P. sanguinolentus)
sand shrimp* (Metapenaeus spp) and other arthropods

* naturally susceptible (other species have been shown to be experimentally susceptible)

Presence in Asia–Pacific

Map showing presence in Asia–Pacific

White spot disease has been officially reported from Bangladesh, Burma (Myanmar), Cambodia, China, Hong Kong, India, Indonesia, Iran, Japan, Malaysia, the Philippines, the Republic of Korea, Singapore, Thailand and Vietnam.


Differential diagnosis

The differential diagnostic table and the list of similar diseases appearing at the bottom of each disease page refer only to the diseases covered by this field guide. Gross signs observed might well be representative of a wider range of diseases not included here. Therefore, these diagnostic aids should not be read as a guide to a definitive diagnosis, but rather as a tool to help identify the listed diseases that most closely account for the gross signs.

Similar diseases

Infectious hypodermal and haematopoietic necrosis, yellowhead disease, Taura syndrome

Further images

Sample collection

Because of uncertainty in differentiating diseases using only gross signs, and because some aquatic animal disease agents might pose a risk to humans, you should not try to collect samples unless you have been trained. Instead, you should phone your national hotline number and report your observations. If samples have to be collected, the agency taking the call will advise you on what you need to do. Local or district fisheries/veterinary authorities could advise you on sampling.

Emergency disease hotline

For your national emergency disease hotline number, see Whom to contact if you suspect a disease.

Further reading


The currently accepted procedures for a conclusive diagnosis of white spot disease are summarised at http://www.oie.int/eng/normes/fmanual/A_00049.htm

These hyperlinks were correct and functioning at the time of publication. white spot disease white spot disease

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