White Spot Syndrome Virus (WSSV)
WSSV is the most economically destructive shrimp virus on record, with 100% mortality possible within 3–10 days of clinical onset.
Clinical signs
- 1–3 mm white calcium deposits on the inner carapace (visible by day 2–4)
- Reddish discoloration of the body and appendages
- Lethargy, reduced feed intake 24–48 hours before mortality spike
- Mass mortality at the pond edge, often at night
- Cumulative mortality 80–100% within 3–10 days of onset
Transmission
- Horizontal: infected post-larvae, broodstock, carrier crustaceans (crabs, copepods)
- Waterborne: virus survives 3–4 days in seawater at 28°C
- Vertical: from infected broodstock to nauplii
- Mechanical: birds, equipment, farm workers moving between ponds
- Trigger temperatures: outbreaks cluster at 22–28°C; >32°C suppresses replication
Diagnosis
- Field: white spots on inner carapace + acute mortality pattern
- Lab: PCR (gold standard) — single-step or nested
- Lab: histopathology of gills, stomach, cuticular epithelium for Cowdry type A inclusion bodies
- Lab: in-situ hybridization for definitive confirmation
Treatment & emergency response
- No effective antiviral treatment exists
- Emergency harvest is the only economic response once mortality begins
- If <30 DOC and mortality <10%: emergency harvest typically loses money — confirm diagnosis first
- If >60 DOC and ABW >12 g: emergency harvest can recover 40–70% of expected revenue
- Chlorinate the pond at 30 ppm for 24 hours before discharging or re-stocking
Prevention
- PCR-screen every PL batch before stocking (zero tolerance)
- SPF (Specific Pathogen Free) broodstock and PLs from certified hatcheries
- Crab fencing and bird netting on every pond
- Disinfect intake water (chlorine 30 ppm, hold 24 h, dechlorinate)
- Maintain salinity 15–25 ppt and temperature >30°C where feasible — stress suppresses virus replication
- Avoid stocking during cool months (Nov–Feb in South Asia)
- Boost immunity with β-glucan, vitamin C and probiotic feed additives
Biosecurity checklist
- Foot baths (200 ppm chlorine) at every pond entry
- Dedicated nets, buckets and aerators per pond
- Worker movement: never from sick pond to healthy pond on the same day
- Quarantine pond for any new PL batch (7 days minimum)
- Daily mortality count + DO + temperature log — anomaly triggers immediate PCR
Regional prevalence
See where WSSV is being reported right now across India and Southeast Asia, with weekly trend lines and per-district drilldowns.
Open the heatmap →Frequently asked questions
What is WSSV in shrimp farming?
WSSV (White Spot Syndrome Virus) is a double-stranded DNA virus in the Nimaviridae family. It infects all life stages of penaeid shrimp and causes the world's most costly aquaculture disease — annual global losses exceed USD 6 billion. Death typically occurs within 3–10 days of clinical signs appearing.
How do you treat white spot disease in shrimp?
There is no cure for WSSV. Once white spots and mortality appear, the only economic response is emergency harvest if biomass and pricing make it worthwhile. After harvest, chlorinate the pond at 30 ppm for 24 hours, dry, lime, and start a strict biosecurity reset before re-stocking.
What temperature kills WSSV?
WSSV replication is suppressed above 32°C and significantly slowed below 18°C. The 22–28°C window — exactly the temperature most South Asian ponds sit at — is where outbreaks cluster. Maintaining pond temperature above 30°C through deeper water columns and aeration is a documented preventive measure.
Can shrimp recover from white spot disease?
Survivors of a WSSV outbreak remain lifetime carriers and continue to shed virus. They can be safely harvested for food (WSSV does not infect humans) but should never be used as broodstock or re-stocked into another pond.
How is WSSV diagnosed?
Field diagnosis is based on the characteristic 1–3 mm white spots on the inner carapace combined with acute mortality. Definitive diagnosis requires PCR, which can detect the virus 4–7 days before clinical signs appear. CAMARON's Disease Vision module gives a high-probability indication from a photo and recommends PCR confirmation.
Catch WSSV before it costs a cycle
CAMARON's Disease Vision module flags WSSV from a single farm photo, ties findings to the regional heatmap, and walks you through the protocol.