Yellow-head disease (YHD) is a highly contagious viral infection that affects Penaeus monodon and Penaeus vannamei shrimp, among other farmed shrimp species. Yellow head virus (YHV), in the family Roniviridae, is what makes sick. The YHV genome is about 25 kb long and has a single strand of positive-sense RNA.
The high death rates and economic effects of YHD have become major worries for the shrimp farming industry. The disease causes the cephalothorax and hepatopancreas to turn yellow. It then causes lethargy, loss of appetite, and eventually death. In affected ponds, more than 80% of the fish can die, which costs farmers a lot of money.
Yellow-Head Disease Management in Shrimp (Prawn)
The Pathogen Responsible for Shrimp Yellow-Head Disease (YHD)
The virus responsible for yellowhead disease is a member of the family Coronaviridae, genus Okavirus, and order Nidovirales. The virus is a cytoplasmic, enveloped, positive-sense, rod-shaped, single-stranded RNA (ssRNA). Shrimp farms in Southeast Asia that cultivate P. monodon in ponds are the primary sources of the Yellow Head Virus (YHV). In conclusion, YHD is a viral disease that primarily affects P. monodon in Southeast Asian shrimp farms.
Spread and Transmission of Shrimp Yellow-Head Disease (YHD)
- Yellow Head Disease (YHD) was discovered in Thailand in 1990 and quickly spread throughout Asia and North America.
- The virus is thought to spread by contact with other infected shrimp or through water polluted with the virus.
- The disease causes infected shrimp heads to become yellow, and the shrimp finally die.
- Yellow Head Virus (YHV) has been found in various aquatic and terrestrial invertebrates and has been linked to significant death rates in shrimp and crabs.
- Cannibalization of infected animals, exposure to polluted water or soil, feeding on infected prey, and viral particles are all ways for the virus to spread.
- Yellow head virus vectors include diseased shrimp, corpses, and tiny chunks of meat from dead shrimp.
What are the Signs and Symptoms of Yellow-Head Disease (YHD) in Shrimp
- Yellowhead sickness in shrimp causes symptoms such as lethargy, lack of appetite, and yellow coloring around the head. Because of lesions, the hepatopancreas becomes yellow, and moribund shrimp congregate towards the pond’s margins.
- Infection with YHV occurs in the late postlarval phases, with illness and death occurring within 2 to 4 days.
- Moderate to high numbers of cytoplasmic inclusions in ectodermal and mesodermal tissues are indicators of YHV infection.
- Shrimp have pale bodies, enlarged cephalothorax, a light yellow to yellowish hepatopancreas and gills, and a substantial decrease in food consumption.
- Within 3-5 days of illness initiation, a high fatality rate