CATDOLL : CATDOLL: Penaeus tularensis is a serious infectious disease of shrimp. How to treat it?

Shrimp Tola Syndrome is a serious infectious disease of shrimp. How to treat it?

Prevalence

The disease was first discovered in Ecuador in June 1992, mainly infecting white shrimp. In 1993, Ecuador's production decreased by 15% and many shrimp farms were closed. Then the infected area quickly expanded to the whole America, including Peru, Colombia, Honduras and Hawaii in the United States. It was introduced to Taiwan in 1999, and the prevalence of Tola syndrome has also been found in Zhanjiang. According to Xing Hua, the disease occurred in Guangdong, Guangxi and Hainan Island in the second half of 2000, and began to break out in Shanghai, Jiangsu, Zhejiang, Shandong, Fujian and Liaoning in 2001, with a mortality rate of up to 40%-60%. It mainly infects 14-60 day old shrimp. The transportation of infected broodstock and shrimp seedlings, animals in water and paese, water bird feces, and frozen shrimp (the virus can survive in the body for more than one year) may all be sources of infection. The disease mainly infects white shrimp Penaeus vannamei, and artificial infection in the laboratory can make Chinese shrimp and Japanese shrimp sick.

symptom

There are three stages with distinct symptoms of Tola syndrome, namely the acute stage, transitional stage and chronic stage. In the acute stage, the whole body of the diseased shrimp is dull red, while the tail fan and swimming feet are obviously red. Carefully observe the epidermis of the small appendages (such as the terminal tail limbs or abdominal limbs) with a 10x magnifying glass, and epithelial necrosis can be seen at the lesion site; in the transitional stage, many shrimps in the infected shrimp pond have a large number of random, irregular black-deposited epidermal lesions.

The lymphatic organs are infected with the virus in the chronic stage, and there are no obvious symptoms at this time. Some shrimp farms that do not take samples regularly do not know when the outbreak of Tola syndrome occurs. They only find that a large number of shrimp are missing during the harvest, and they cannot explain it. The shrimp that survived the Tola syndrome epidemic had no symptoms or necrosis in appearance and tissue pathology. Only the spheroids in the lymphatic organs were the only most obvious lesions when the shrimp was continuously infected with Tola virus. The cells formed spherical accumulations, and lacked the central duct of the normal lymphatic organ tubules. The diseased shrimp that survived the chronic infection period carried the virus for life.

diagnosis

Initial diagnosis is based on symptoms, histology, and prevalence. Confirmation is by DNA probe and polymerase chain reaction.

Precautions

According to Xing Hua, the pond is thoroughly cleaned by comprehensive pond cleaning method before stocking. During the whole breeding process, especially after 10 days of cultivation of white shrimp, photosynthetic bacteria should be frequently used, 2-5 ml or "clean water" per cubic meter of water, and 0.25 grams of "dry shrimp" per cubic meter of water to improve the water environment of the shrimp pond. At the same time, antiviral drug feed is fed 2-4 times every 15 days, with 2 grams of immune polysaccharide added to each kilogram of feed, 1 gram of "biological enzyme active additive" and 5 grams of "white shrimp red body elimination".

Prevention methods

Combine external spraying with internal medication and feeding. Sprinkle "Qiangke 101" super iodine quaternary ammonium salt throughout the pond, 0.2 grams per cubic meter of water, for 2 consecutive days. Sprinkle dibromodimethoate compound disinfectant on the third day, 0.2 grams per cubic meter of water. After 2 days, spray "Qingshuisu" throughout the pond again, 0.3 grams per cubic meter of water, and activated carbon, calcium peroxide, and open-hearth slag mixture, 5 grams per cubic meter of water. Feed internally for 3-5 days, feed twice a day. Add 15-20 grams of "Bai Xia Hongti Xiao" plant antiviral protein, 1-2 grams of biological enzyme activity additives, 33% stable vitamin C content, 2-3 grams and 10-20 grams of fish oil to each kilogram of feed.

Treatment of shrimp Tola syndrome: drug treatment (anti-TSV drugs), TSV purification, anti-virus technology, anti-TSV related genes

Add the drug to the shrimp bait and feed it continuously for 20 days after stocking. It can effectively prevent and treat TSV. In the epidemic season, spray the drug in the whole pond every 5 to 7 days, and continue to spray the drug in the whole pond every half a month.

Some medicines need to be used, and attention should be paid to the specific conditions of the water, keeping it clean and hygienic, so that the problem can be better solved.

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