pathogen
The pathogen of prawn tarantulas is the taura virus with a diameter of 31-32 nm, virus particles of 30-32 nm and single-stranded RNA. The main host was Penaeus vannamei, and the target organs were carapace epithelium (appendages, sputum, stomach, esophagus, hindgut) and connective tissue.
symptom
Disease shrimp do not eat, there is no food in the digestive tract; swimming is weak, unresponsive, carapace becomes soft, shrimp body redness, especially the tail fan becomes red, juvenile shrimp (0.05 g to 5 g) has serious disease, the mortality rate is as high as 80%. The survivors have dark spots on the carapace, which are blackened lesions on the keratin of shrimp shells.
Poisonous broodstock and shrimp seedlings, water and crustaceans, water bird droppings, and frozen shrimp (viruses that can survive in the body for more than a year) may be the route of transmission.
Taura virus has two stages of acute and recovery (chronic phase). The symptoms are somewhat different. Acute infection often occurs during the larval period. After the shrimps are stocked in the disease prevention and control pool (14 days to 40 days), diseases will occur and the shrimp population will die. The mortality rate is as high as 90%. Diseased shrimp do not eat, drowsiness, surface pigmentation spread, redness of the limbs and tail. The remaining shrimp will become chronically infected and will become acutely infected again during the next molting. Adult shrimps are mostly chronic infections, the mortality rate is usually less than 50%, and there are multiple necrotic areas in the shell. Individuals with epidermis that remain in the acute stage and remain in the molting stage will have a number of randomly-distributed irregular melanotic pigmentation lesions that are characteristic of the chronic phase and early stage of recovery. Most of the shrimps in the chronic phase have normal behavior. After being molted, the diseased shrimp will get rid of the outer skin with black spots. There is no black spot on the skin of this diseased shrimp, but some shrimps have faded appearance on their appearance. These injuries may be traces of the original area of ​​necrosis. DNA probes are currently available to diagnose the disease.
popular
Major epidemic areas: Found in the United States, Panama, Ecuador, China, and Taiwan.
Prevention
The imported broodstock must be strictly tested and it is forbidden to purchase smuggling vaccines and broodstock of unknown origin. Taura virus and infectious subcutaneous and hematopoietic tissue necrosis virus are prevalent in the Americas. The most powerful preventive measure is to prevent the virus from entering our country.
During the disease, it is treated like white spot virus disease.
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