Studies On The Pathogens Of Hemorrhage Disease And Parasitic Helminths In Rice Field Eels(Monopterus Albus) In Sichuan Province, China

Rice field eel (Monopterus albus Zuiew) is a fish variety of high economic value in China and is popular for its delicious taste. With the rapid development of human breeding, studies on diseases of Monopterus albus nevertheless were detained relatively. Scientific guidance for healthy breeding and disease prevention and cure is lacking which hinders the human breeding of Monopterus albus. Sichuan province is the major producing area of rice field eel in China. Little is known about hemorrhagic disease and parasitic helminths. The hemorrhagic disease which is characterized for its rapid onset and high infectivity is a major disease of Monopterus albus.The parasitic helminthes is also a major disease of Monopterus albus. The parasites consume the internal nutrients, damage the apparatus, hinder the growth and reduce the immunity which results in other diseases. The manual infection, bacteria general taxonomy and identification method, the morphological, physiological, biological and phylogenetic analysis were used in this study to isolate and identify the pathogens of hemorrhagic disease. Investigation of the infection of parasite was conducted using conventional methods in order to provide scientific evidence and theoretical reference for disease prevention and control through the breeding process.1. Isolation, identification and antibiotic susceptibility tests on Aeromonas hydrophilaHemorrhagic disease pathogens of 13 areas in Sichuan were isolated and identified according to the morphological, physiological and biological characteristics and the results of phylogenetic analysis.14 strains of Gram-negative bacillus identified from the rice field eel tissues of 10 areas selected from 13 natural onset areas were Aeromonas hydrophila. All isolated strains on common nutrient agar presented bacterium colonies with a round shape of neat edge with a central uplift, the surface was smooth and translucent with a white-gray color. Animal infection tests demonstrated that it is strongly pathogenic to Misgurnus anguillicaudatus, Ictalurus nebulosus and mouse. Antibiotic susceptibility tests of 24 pharmacons showed:14 strains were susceptible to 15 pharmacons such as nalidixic acid, norfloxacin, cefuroxime and tetracycline, to different extents susceptible to 5 pharmacons such as polymyxin B sulfate and imipenem and were insusceptible to 4 pharmacons such as sulfafurazole, carbenicillin and ampicillin.2. Isolation, identification and antibiotic susceptibility tests on Micrococcus luteusHemorrhagic disease pathogens of 13 areas in Sichuan were isolated and identified according to the morphological, physiological and biological characteristics and the results of phylogenetic analysis.1 strain of Gram-positive coccus pathogen was identified as Micrococcus luteus from the Monopterus albus tissues of hemorrhagic disease in Mingshan area. Bacterium colonies with a round shape of neat edge with a central uplift can be observed, the surface was smooth and opaque with a cream color. Animal infection tests demonstrated that it's not pathogenic to Misgurnus anguillicaudatus and mouse and is slowly pathogenic to Ictalurus nebulosus. Antibiotic susceptibility tests of 24 pharmacons showed:Micrococcus luteus was susceptible to 18 pharmacons such as norfloxacin, cefazolin sodium and carbenicillin and was moderately susceptible to ceftazidime and insusceptible to 5 pharmacons such as nalidixic acid, gatifloxacin and sulfafurazole.3. A Study on parasitic helminths in Monopterus albus in Sichuan ProvinceDuring July to August in 2008,435 rice field eels were collected in Sichuan Province, China, including Meishan, Leshan, Mianyang, Deyang, Ziyang, Neijiang, Guang'an, Nanchong, Suining, Yibin, Xichang, Qionglai and Mingshan. Three kinds of helminthes parasitizes were found in the rice field eels, The infected rates and the infection intensity of them were significant different. The results showed that the infection rate of Eustrongylides sp.(larva) was 19.08%; the infection rate of Pallisentis(Neosentis) celatus was 18.85%; the infection rate of Phylldistomum serripatula was 4.83%. According to the data in this study, for the health of aquaculture for rice field eel, the three species of parasites should be paid more attention to prevent and control.