On May 15th, the newspaper reported on the highly pathogenic PRRS (for details, see the 10th edition of the newspaper on May 15, “Families Worried about Fighting Vaccines and Killing Pigsâ€), which has aroused widespread concern in the breeding industry. Does the phenomenon of accidental occurrence of dead pigs after the injection of blue ear disease vaccines reflected by individual households, or is it widespread? Is there a problem with the quality of the vaccine? Can the new inactivated vaccine promoted by the Ministry of Agriculture work effectively? What measures should be taken in the control of highly pathogenic PRRS in small and medium farms? The reporter interviewed a number of experts in domestic research on PRRS against these issues. Experts unanimously suggested that the current vaccination is the preferred measure for preventing and controlling the outbreak of PRRS, and that farms (households) should be injected with vaccines in time to enhance the immunity.
The new inactivated vaccine is worth the wait
Professor Wang Guiping, director of the Institute of Veterinary Medicine, Guangdong Academy of Agricultural Sciences, believes that the incidence and death of pigs after vaccination may be due to the fact that pigs were infected with the highly pathogenic PRRS virus before the vaccination. The virus is in pigs. The body has undergone a large number of reproductions, and the stress response caused by the vaccination at this time will help the virus's onset. Therefore, this situation is basically not a problem of vaccine quality.
Wang Guiping said that the effect of the blue ear disease vaccine that originally circulated on the market was not obvious for the currently highly pathogenic strains of the highly pathogenic PRRS virus. The newly developed highly pathogenic inactivated blue-ear ear disease vaccine developed by the China Animal Disease Control and Prevention Center and the China Veterinary Medicine Supervision Institute uses the mutant strain of the blue-ear disease virus extracted from the epidemic area of ​​pig high fever last year as a species of virus. The trials are in good effect and are being urgently produced by 6 companies. Their clinical application of immune effects is worth looking forward to (see the 7th edition of the newspaper on May 19).
Professor Yang Hanchun of China Agricultural University believes that the inactivated vaccine of the new mutant strain promoted by the Ministry of Agriculture needs to be further validated in terms of the effectiveness of immunization in actual production. As for the other blue-virus disease virus strains, the immune effect also lacks the test of actual effect, and the blue-ear virus itself has a strong variability. The cross-immune protection effect between different strains is not very good, which is also the problem of preventing and treating blue ear disease.
Dr. Fan Fuhao of the Quality Supervision, Inspection and Test Center of the Ministry of Agriculture (Guangzhou) stated that vaccination is only an expedient measure to prevent and control highly pathogenic blue ear disease. Inactivated vaccines are incompletely inactivated by products of individual manufacturers on the market. The attenuated vaccines are mixed with virulent poisons. It is recommended that farmers adopt caution when selecting vaccine products.
Shi Yan, manager of Shanghai Boehringer Ingelheim Pharmaceutical Co., Ltd., believes that so far, no complete blue-ear disease prevention program has been established in production, and grass-roots veterinarians have relatively agreed with the use of the blue-eared disease virus vaccine.
Fan Fuhao and other experts analyzed that although attenuated vaccines may be better than inactivated vaccines in actual effect, in the current situation, the use of attenuated vaccines can easily infect pig farms that are not infected with viruses. From the perspective of biosafety, inactivation is recommended. vaccine. Wang Guiping said that the current vaccines targeting new variant strains are mainly inactivated vaccines, and the attenuated vaccines have not been popularized by the Ministry of Agriculture because of the long experimental period and low biosafety evaluation.
Management loopholes provide a breeding ground for outbreaks
Experts said that the production cycle of new vaccines should be at least 1-2 months. During this period, the effective immunization of PRRS in small and medium-sized pig farms is particularly critical.
According to the analysis of the epidemic distribution pattern of the high fever epidemic in the summer last year, highly pathogenic blue-ear ear disease is mainly concentrated in small-medium-sized pig farms and free-range farmers. The consistent characteristics of these farms (households) are: poor feeding environment, Poor management conditions.
Wang Guiping believes that this shows that the incidence of highly pathogenic PRRS is closely related to the feeding and management environment of pig farms. It is precisely the loopholes in the production management of small and medium-sized farms and free-range pigs that are highly pathogenic to pig blue. Ear disease provides a breeding ground for outbreaks. Poor feeding conditions, poor quality of feed ingredients, abuse of antibiotics, and indiscriminate use of vaccines all lead to a decline in the overall immune function of the pig's body and decreased resistance. According to reports, at present, the infection rate of PRRS in domestic pig farms is relatively high, and most of them do not show clinical symptoms. Once the virus has become a highly pathogenic strain, it will trigger an outbreak.
Wang Guiping analysis, the main route of transmission of highly pathogenic blue-ear disease is the introduction of breeding pigs. Therefore, in the current severe epidemic situation, small and medium-sized pig farms must strictly introduce good breeding pigs to this level, improve the feeding environment, improve the quality of feed ingredients, and increase the immune status of the pig itself.
Yang Hanchun said in an interview that antibiotics have no effect on PRRS. The use of antibiotics not only does not alleviate the disease, but also aggravates the condition and accelerates the death of pigs. Therefore, antibiotics should be used cautiously for already infected pigs. At the same time, he suggested that some Chinese herbal medicines or some immunopotentiating agents could be added to feeds to help improve the nonspecific immunity of herds.
Fan Fuhao also stated that reducing the use of antibiotics in swine production and reducing excessive types of vaccination is an effective way to improve the immune status of herds.
Yang Hanchun analyzed that the blue ear disease is very difficult to completely remove from the farm, and it will stabilize after the epidemic. Judging from the current situation, pig farms that had an epidemic last year still endanger the suckling pigs, nursery pigs, and breeding sows. Therefore, after the onset of the disease, the pig farms and regions still need to pay attention to strengthening the prevention work.