Prevention and Control Methods for Microsporidiosis in Farmed Shrimp

(1) Pathogen In China, 3 species have been found: Ameson on the bodies of Chinese shrimp (Penaeus chinensis) and banana prawn (Penaeus merguiensis), Agmasoma on the body of banana prawn, and Pleistophora on the body of white shrimp (Penaeus penicillatus). The spores are slightly oval or pear-shaped, measuring 2 to 10 micrometers long and 1.5 to 4.2 micrometers wide; the internal structure can only be seen clearly under an electron microscope. The transmission route of this disease is not very clear. 

(2) Symptoms Symptoms vary with infection by different species of pathogens. After Ameson parasitizes the muscles of banana prawn and Chinese shrimp, the muscles of the diseased shrimp turn white and turbid, become opaque, and lose elasticity, so some people call them milky-white shrimp or cotton shrimp; after the ovaries of banana prawn are infected with Agmasoma, the carapace often turns orange-red. Microsporidiosis is a chronic disease; usually the diseased shrimp gradually become weakened and finally die. 

(3) Diagnosis A preliminary diagnosis can be made based on symptoms and lesions. However, viral diseases, vibriosis, and muscle necrosis disease can also cause shrimp muscles to turn white. Therefore, whitened tissue must be taken to make a smear or wet mount, and if sporoblasts can be observed under a high-power microscope, a confirmed diagnosis can be made. 

(4) Epidemiology Microsporidiosis is a relatively common and highly harmful disease in Guangdong and Guangxi. It is a chronic disease, and during the entire disease prevention and control cycle, the infection rate can reach 90%, and the cumulative mortality rate can exceed 50%. Among shrimp undergoing disease prevention and control in Qingdao, Shandong, acute infection once occurred in juvenile shrimp with a body length of 1.5 to 3.0 cm, causing all the juvenile shrimp in several hundred mu of ponds to die within two weeks. 

(5) Prevention and Control Currently there is no effective method. Yu Xia Zhuang Yuan 5% can be mixed evenly with every kilogram of feed and fed continuously for 3 days.