In the black tiger shrimp farming industry, farmers are not infrequently faced with a crisis when they suddenly see their shrimp swimming sluggishly, the head turning yellow, and the number of deaths rising rapidly. These are signs of yellow head disease in shrimp (YHD), caused by Yellow Head Virus, which can wipe out an entire stock in a very short time. Let’s join Vemedim to learn about the causes of the disease and how to prevent and treat it so you can protect your shrimp stock and avoid major economic losses right away.
Signs of yellow head disease in shrimp
Yellowhead Disease (YHD) is one of the most dangerous diseases for farmed shrimp, especially black tiger shrimp. When shrimp are infected, mortality is very rapid and can occur in outbreaks within just a few days, causing severe losses for farmers. The disease is caused by Yellow Head Virus (YHV) and Gill-Associated Virus (GAV), which belong to the RNA virus group in the Roniviridae family.
Species that are easily affected include black tiger shrimp, whiteleg shrimp, and some other marine shrimp species. Yellow head disease in shrimp usually appears in farmed shrimp from 30 days of age and older and progresses very quickly if not detected early. Shrimp infected with YHD show the following typical signs:
- Color changes: The cephalothorax and gills turn yellow or light brown, and the whole body becomes paler than healthy shrimp.
- Swollen cephalothorax, enlarged digestive gland: An increase in cephalothorax size and swelling of the hepatopancreas, indicating damage to internal tissues.
- Abnormal behavior: Shrimp eat a lot suddenly during the first 1–2 days, then stop eating, swim sluggishly, lose orientation, and move toward the shore.
- Mortality rate: Very high, reaching up to 100% within 3–5 days after symptoms appear.
Histopathology: Examination of hepatopancreatic tissue, hemocytes, lymphoid organ, gills, intestine, antennal gland, and connective tissue shows that yellow head disease in shrimp causes:
- Cell necrosis and nuclear fragmentation.
- Cytoplasmic inclusion bodies.
- Fragmentation and separation of lymphoid cells, hepatopancreas, and gills.
These symptoms can sometimes be confused with other diseases, so accurate diagnosis is very important.
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Transmission route of yellow head disease in shrimp
The main causative agents are Yellow Head Virus (YHV) and Gill-Associated Virus (GAV), RNA viruses belonging to the Roniviridae family. The virus invades ectodermal and mesodermal tissues: the lymphoid organ, hemocytes, intestine, gills, hepatopancreas, antennal gland, gonads, and nerve ganglia, causing the shrimp’s head to turn a characteristic yellow color. The transmission routes of yellow head disease in shrimp are:
- Horizontal transmission: Through cannibalism, pond water, or virus-carrying objects.
- Vertical transmission: From broodstock to offspring through eggs and postlarvae.
The virus can survive and remain infectious in water for up to 72 hours.
- Susceptibility:
- Black tiger shrimp are easily infected from the postlarval stage (PL15).
- Other shrimp species are usually infected at 40–70 days of age.
- Mortality can reach 100% within 3–5 days after symptoms appear.
How to handle shrimp ponds when yellow head disease appears and how to prevent it
When YHD is detected in shrimp, farmers should take the following steps to limit losses:
- Harvest the shrimp: If the shrimp are large enough, harvest immediately to reduce mortality.
- Dispose of diseased shrimp: Bury or burn them; absolutely do not discharge untreated water into the environment.
- Treat pond water: Use Vemedim Anti Parasite - an environmental treatment product specialized in eliminating disease-causing agents in pond water such as fungi, bacteria, viruses, parasites, etc., to destroy viruses before adding new water.
- Clean the pond: Dredge the pond bottom, remove accumulated mud, sand, and organic matter, dry the pond for 5–7 days, and eliminate intermediate crustaceans that carry pathogens.
- Disinfect equipment: Heat at 60°C for 15 minutes or treat with chlorine at a concentration of 30 ppm.
These measures help prevent the spread of the virus and prepare the pond safely for the next crop.
Preventing yellow head disease in shrimp is always the most effective strategy because there is no specific treatment for YHD yet. Farmers should note:
- Choose disease-free seed: Use healthy shrimp that are not infected with YHV.
- Prepare the pond before stocking: Dredge, dry, wash, and install net fencing to keep out intermediate organisms.
- Treat the water: Disinfect the water long enough to prevent the virus from surviving.
- Boost resistance: Supplement with vitamin C, minerals, and probiotics Enter Lactyl plus to help balance the water environment and limit pathogen growth.
- Manage the environment: Maintain dissolved oxygen, pH, and alkalinity within appropriate ranges to reduce stress on shrimp.
- Post-harvest sanitation: Remove mud and organic matter, and treat thoroughly so pathogens do not accumulate at the pond bottom.
These steps help reduce the risk of YHD outbreaks and effectively protect crop productivity.
Yellow head disease in shrimp progresses very quickly and is difficult to treat, causing enormous losses for shrimp farmers. Therefore, proactive disease prevention, strict management of seed stock and the farming environment are always the most effective solutions. With Vemedim’s experience and specialized solutions, farmers can feel more confident when preparing and operating their shrimp farming model, thereby improving productivity and avoiding the risks caused by YHD.
