Reproductive and respiratory syndrome of pigs in pig breeding enterprises (review)

Porcine Reproductive Respiratory Syndrome (PRRS) causes significant economic losses in pig production around the world. The virus is highly contagious and spreads both by aerosol and with all biological secretions, and the disease itself is characterized by fever, weight loss and abortion of fetuses. This swine disease is relatively new, for the first-time clinical signs were described in 1986, and in 1991 the pathogen was isolated. The main problems hindering the fight against the virus currently remain: the insufficient effectiveness of existing vaccines, the high genetic variability of the pathogen, the ability of PRRSV to suppress the host's immune system, and long-term virus carriers in recovered animals. The review on porcine reproductive and respiratory syndrome presents data on the genetic diversity of virus strains that differ in the degree of virulence and pathogenicity, sources of infection and ways of transmission of the virus. The article also contains data on the spread of PRRS in the world and in Russia. It is noted that the disease has been reported in many swine-producing countries, where, after a phase of active spread, the disease became endemic. And in 2021, according to the to the International Epizootic Bureau (OIE), outbreaks of PRRSV were detected in domestic pigs in Ecuador, Uruguay, Nepal, China, Bahrain, Switzerland and Ukraine, as well as in wild boars in Bahrain, Switzerland and Ukraine. According to the published data of monitoring studies conducted in the period from 2012 to 2017, only single territorially limited outbreaks were detected in Russia. Earlier studies indicate a wide distribution of the PRRS pathogen in Russia. The effectiveness of various variants of live and inactivated vaccines is described in detail, and it has been established that live attenuated vaccines are most effective against PRRS. The features of the protection of the territory of a number of states (Norway, Sweden, Finland, Switzerland) from the introduction of the pathogen, which by now remain free from PRRS, as well as the experience of Hungary in the eradication of the disease, are analyzed. All preventive measures in the pig farm in case of detection of the virus should include general, veterinary-sanitary and special measures, for diagnosis it is better to use modern RT-PCR test systems that allow distinguishing PRRS genotypes, in combination with serological tests, and for vaccination choose a registered and approved vaccine based on the genetic characteristics of the pathogen circulating in the area.