Epidemiological Investigation Of Five Important Virus Diseases On Large-scale Goose Farms In Some Regions In China

China is the first state of geese industrial in the world, the breeding stock and slaughter of geese have always remained steady in the first place, and meat geese industrial is one of the pillar industries of our national agriculture. Nonetheless, with the development of geese industrial large scale farming and increasing stocking density, infectious diseases of geese especially avian influenza virus, Newcastle disease virus, Tembusu virus, Goose circovirus are increasing year by year. These diseases with single infection and co-infection could cause death or losses of production performance of geese, which have always been damaging the health of our national geese breeding industry and caused enormous economic losses.1. Establish a rapid detection method, is an important measure to epidemiological investigation of infectious diseases. Three pairs of specific primers were designed and synthesized based on the HA gene of AIV-H9, HN gene of Newcastle disease virus, and NS3 gene of Tembusu virus. Trizol methods were used to extract RNA of H9-AIV, NDV and TMUV, then mixed cDNAs which have been reverse transcriptase as templates of PCR systems. On the basic of common PCR method, we optimized reaction systems and conditions such as annealing temperature, E×Taq DNA polymerase, concentrations of Buffer, dNTP, and established multiplex RT-PCR method to amplify H9-AIV(550bp), NDV(427bp) and TMUV(277bp) at the same time. The results showed that in the same PCR reaction systems, three viruses could be detected at the same time, and the detection results of GRV, HDV, DRV were negative; the detection limits of H9-AIV, NDV and TMUV are 5.8×105 copies,7.2×105 copies and 4.6×105 copies respectively. This method was used for detecting clinical samples, of which the results is consistent, those above could prove multiplex RT-PCR method can be used to detect H9-AIV, NDV and TMUV at the same time, while it also has advantages of simple, quick, good specificity, high sensitivity and strong practicability. It could provide effective method to detect and diagnose geese’diseases, so that we can take measures to prevent and control these diseases in time, and reduce the harm to geese industry.2. In order to understand epidemic dynamics of main geese viral diseases in China, we have collected 478 samples of infectious geese in large-scale geese farms of 14 provinces during 2014-2015 in this research, established multiplex RT-PCR and common PCR detection method were used to detect H9-AIV, NDV, TMUV and Goose circovirus. Results showed that there are 190 single infections,80 double infections,30 triple infections,3 quadruple infections in the 478 samples, and positive rates are 40%,17%,6% and 1% respectively, negative infections are 173(about 36%), and positive rates of GPV, H9-AIV, NDV, TMUV and GoCV infections are17.1%,21.7%,18.4%,16.5%,21.7% respectively. GPV, H9-AIV, NDV, TMUV and GoCV, co-infection rates are higher which is 55%,62%,74% and 64% respectively, while it could be lower of NDV, which is 44%. The result of five kinds of virus-infected in different seasons shows that virus disease has the highest incidence in the spring and winter, meanwhile, has low incidence in summer, autumn season, In particular, with the lowest incidence of summer. According to the different age, positive rate of H9 and GoCV are very high, and the old geese is the highest; positive rate of NDV in goslings is higher than other ages; positive rate of TMUV is similar in different age, but goslings and old geese are on the high side. The infection rate is high with goslings, breeding geese and old geese may also be infected but the probability is low.In conclusion, infections of H9-AIV, NDV, TMUV and GoCV are existing wildly in mostly large-scale goose farms in China, and phenomena of single infection and co-infection are serious. Double infections are primary in co-infection, and co-infection rates with immunosuppressive pathogens are higher, which has been one of the reasons that geese diseases are difficult to prevent and control in large-scale farms of our country.