Yellow Head Disease (YHV)
Yellow Head Disease (YHD) is one of the three most destructive shrimp viruses on record — a pale-yellow cephalothorax, brief feed surge then collapse, and 100% pond mortality within 3–5 days of clinical onset.
Clinical signs
- Pale yellow to yellow-brown cephalothorax (head region) — the diagnostic field sign that gives the disease its name
- Pale, bleached gills and an overall faded body colour
- Sudden, brief surge in feed intake 2–4 days before mortality, followed by abrupt feed refusal
- Moribund shrimp gather at pond edges and the surface, swimming slowly near the dyke
- Cumulative mortality reaches 80–100% within 3–5 days of the first clinical signs
- Onset typically between DOC 50–70 in grow-out ponds; rarely seen in PL stages
Transmission
- Horizontal via water — virus sheds from infected shrimp and is taken up by cohabitants within hours
- Cannibalism of dead and moribund shrimp is the fastest spread route inside a pond
- Vertical transmission from infected broodstock to nauplii is documented — PCR-screen all spawners
- Carrier crustaceans (wild Palaemonid and Penaeid shrimp, krill, Acetes) maintain the virus in source water
- Contaminated nets, buckets, feed trays and worker hands carry the virus between ponds
Diagnosis
- Field: yellow cephalothorax + dyke-edge mortality + the pre-collapse feed surge is highly suggestive in endemic regions
- RT-PCR on haemolymph, gill or lymphoid organ — OIE reference method, results in 4–6 hours
- Histopathology of lymphoid organ shows characteristic basophilic cytoplasmic inclusions
- In situ hybridisation or immunohistochemistry confirms YHV genotype 1 (the virulent strain) and distinguishes from non-pathogenic genotypes 2–8
- Always submit paired samples from moribund and apparently healthy shrimp to confirm pond-level prevalence
Treatment & emergency response
- There is no treatment for YHV — antibiotics, antivirals and probiotics have no effect on viral replication
- Emergency harvest at the first confirmed RT-PCR positive is the only way to recover any biomass value
- If shrimp are above 12 g, harvest, ice, and route to processing within 4 hours — meat is safe for human consumption when properly cooked
- Below 12 g or in late-stage collapse: chlorinate the pond at 30 ppm for 72 hours before discharge — never release untreated water
- Quarantine all equipment, restrict farm access, and notify the regional aquatic health authority — YHV is OIE-listed and notifiable
Prevention
- Stock only SPF (Specific Pathogen Free) post-larvae from RT-PCR-screened broodstock — the single highest-impact intervention
- Sand-filter and chlorinate (20 ppm, 24 hours, then dechlorinate) all incoming source water to inactivate carrier crustaceans
- Fence ponds and screen inlets (250 µm) against wild Palaemonid shrimp, Acetes and krill
- Run a 90-day fallow with full pond drying, lime treatment (1 t/ha) and sun exposure between cycles in any region with prior outbreaks
- PCR-screen post-larvae before stocking — reject any batch with detectable YHV genotype 1
- Coordinate stocking dates with neighbouring farms in the same water source to create a buffer-zone fallow
Biosecurity checklist
- RT-PCR certificate on every post-larvae batch before stocking, retained for 2 years
- Foot baths with 200 ppm chlorine at every pond entry, refreshed daily
- Dedicated nets, buckets and feed trays per pond; never share equipment between ponds
- Daily feed intake and mortality log per pond — a brief feed surge is the earliest warning signal
- Lockable pond gates and a visitor log; restrict access to trained farm staff only during DOC 40–80
- Inlet water chlorinated and held for 48 hours minimum before transfer to grow-out
- Written outbreak response plan: emergency harvest threshold, chlorination protocol, notification contacts
Regional prevalence
See where YHD / YHV 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 Yellow Head Disease in shrimp?
Yellow Head Disease (YHD) is an acute viral infection of penaeid shrimp caused by Yellow Head Virus (YHV) genotype 1. It produces a pale-yellow cephalothorax, a brief feed surge then collapse, and 80–100% pond mortality within 3–5 days. YHV is OIE-listed and notifiable. There is no treatment — only prevention through SPF post-larvae, water chlorination and screened inlets.
How do I tell YHD apart from WSSV?
WSSV produces 1–3 mm white calcium spots on the inner carapace and reddish body discoloration. YHD produces a pale-yellow cephalothorax and bleached gills, without white spots. WSSV often shows a slow 7–10 day mortality curve; YHD collapses faster (3–5 days). Both are critical viral diseases requiring RT-PCR confirmation and an emergency-harvest decision, but field signs are distinct.
Is Yellow Head Virus a risk to people who eat the shrimp?
No. YHV infects only crustaceans and has no documented human health impact. Properly cooked shrimp from a YHD-affected pond is safe to consume. However, never sell or distribute live or chilled shrimp from a confirmed YHV-positive pond into the seedstock or live-trade supply chain — that is how the virus reaches new regions.
Can YHV be treated with antibiotics or probiotics?
No. YHV is a virus, not a bacterium, so antibiotics have zero effect. Probiotics, immunostimulants and herbal additives may modestly improve baseline shrimp health but do not stop viral replication or alter the mortality curve once clinical signs appear. Emergency harvest at first PCR-positive is the only practical response.
When during the crop is YHD most likely to appear?
YHD is overwhelmingly a grow-out disease, with outbreaks clustering between DOC 50 and 70. Onset before DOC 30 is rare. The pre-collapse feed surge typically appears 2–4 days before visible mortality — daily feed intake logs are the earliest warning signal and should trigger immediate RT-PCR sampling.
Where in the world is YHD endemic?
YHD is endemic across Thailand, Vietnam, Indonesia, the Philippines, India and parts of southern China. Sporadic outbreaks have been reported from Latin America and Australia. Any farm sharing a water source with an endemic region must operate full biosecurity — chlorinated inlets, screened intakes, SPF post-larvae and a written outbreak response plan.
Catch YHD / YHV before it costs a cycle
CAMARON's Disease Vision module flags YHD / YHV from a single farm photo, ties findings to the regional heatmap, and walks you through the protocol.