The current African swine fever (ASF) epizootic in Europe and Asia has clearly highlighted the crucial role of effective biosecurity in preventing and controlling infectious diseases and in ensuring a high health status of the herd. The role of feed in the mechanical transmission of viral pathogens has long remained unclear, but the unexpected emergence of porcine epidemic diarrhea (PED) in the United States in 2013 led to intensified research efforts aimed at determining the origin of PEDV. Since then, it has been proven that feed and feed materials can play a role of mechanical vectors for many pathogens, including PEDV, ASFV, FMDV, PRV, PRRSV, PVDV, PCV2, CSV and PRV. In light of the potential risk of virus transmission via imported contaminated feed, a number of preventive measures have been developed and experimentally proven to be effective in mitigating the risk. The aim of this study is to summarize the current knowledge on the potential role of feed in the spread of porcine viral pathogens and on the latest efforts aimed at reducing the risk of such transmission.
Abstract In Poland, African swine fever (ASF) emerged in February 2014; by August 2015, the virus had been detected in >130 wild boar and in pigs in 3 backyard holdings. We evaluated ASF spread in Poland during these 18 months. Phylogenetic analysis indicated repeated incursions of genetically distinct ASF viruses of genotype II; the number of cases positively correlated wild boar density; and disease spread was very slow. More cases were reported during summer than autumn. The 18-month prevalence of ASF in areas under various animal movement restrictions was 18.6% among wild boar found dead or killed by vehicles and only 0.2% in hunted wild boar. Repeated introductions of the virus into the country, the primary role of wild boar in virus maintenance, and the slow spread of the disease indicate a need for enhanced biosecurity at pig holdings and continuous and intensive surveillance for fast detection of ASF.
Twenty-nine Marek's disease virus (MDV) strains were isolated during a 3 year period (2007-2010) from vaccinated and infected chicken flocks in Poland. These strains had caused severe clinical symptoms and lesions. In spite of proper vaccination with mono- or bivalent vaccines against Marek's disease (MD), the chickens developed symptoms of MD with paralysis. Because of this we decided to investigate possible changes and mutations in the field strains that could potentially increase their virulence. We supposed that such mutations may have been caused by recombination with retroviruses of poultry - especially reticuloendotheliosis virus (REV). In order to detect the possible reasons of recent changes in virulence of MDV strains, polymerase chain reaction (PCR) analyses for meq oncogene and for long-terminal repeat (LTR) region of REV were conducted. The obtained PCR products were sequenced and compared with other MDV and REV strains isolated worldwide and accessible in the GeneBank database. Sequencing of the meq oncogene showed a 68 basepair insertion and frame shift within 12 of 24 field strains. Interestingly, the analyses also showed 0.78, 0.8, 0.82, 1.6 kb and other random LTR-REV insertions into the MDV genome in 28 of 29 of strains. These genetic inserts were present after passage in chicken embryo kidney cells suggesting LTR integration into a non-functional region of the MDV genome. The results indicate the presence of a recombination between MDV and REV under field conditions in Polish chicken farms. The genetic changes within the MDV genome may influence the virus replication and its features in vivo. However, there is no evidence that meq alteration and REV insertions are related to the strains' virulence.
Journal Article Common occurrence of Gallid herpesvirus‐2 with reticuloendotheliosis virus in chickens caused by possible contamination of vaccine stocks Get access G. Woźniakowski, G. Woźniakowski Department of Poultry Viral Diseases National Veterinary Research Institute Puławy Poland Correspondence Grzegorz Woźniakowski, Department of Poultry Viral Diseases, National Veterinary Research Institute, Partyzantów 57 Avenue, 24‐100 Puławy, Poland. E‐mail: grzegorz.wozniakowski@piwet.pulawy.pl Search for other works by this author on: Oxford Academic Google Scholar A. Mamczur, A. Mamczur Avi‐Vet Service J. Mamczur, Szeptycki S.J. Tarnowo Podgórne Poland Search for other works by this author on: Oxford Academic Google Scholar E. Samorek‐Salamonowicz E. Samorek‐Salamonowicz Department of Poultry Viral Diseases National Veterinary Research Institute Puławy Poland Search for other works by this author on: Oxford Academic Google Scholar Journal of Applied Microbiology, Volume 118, Issue 4, 1 April 2015, Pages 803–808, https://doi.org/10.1111/jam.12734 Published: 01 April 2015 Article history Received: 17 June 2014 Revision received: 19 December 2014 Accepted: 19 December 2014 Published: 01 April 2015
African swine fever (ASF) causes huge economic losses and is one of most dangerous diseases of pigs. The disease is known for almost 100 years, an effective vaccine or treatment is still unavailable, only proper biosecurity measures, including disinfection, are being applied, in order to prevent disease outbreaks. Eight active substances, i.e., formaldehyde, sodium hypochlorite, caustic soda, glutaraldehyde, phenol, benzalkonium chloride, potassium peroxymonosulfate and acetic acid, were tested, in order to confirm their effectiveness against African swine fever virus (ASFV). This specific selection was done based on the World Organisation for Animal Health (OIE)’s recommendation and previous disinfectant studies on surfaces. The result of our study shows that most of them inactivate the virus, in recommended concentrations. In order to reduce the cytotoxicity of the four substances, Microspin S-400 HR columns were applied, therefore making it possible to demonstrate four logarithms virus titer reduction. Sodium hypochlorite, glutaraldehyde, caustic soda and potassium peroxymonosulfate showed the best ASFV inactivation rates, achieving titer reductions over 5 logs. Despite microfiltration, the virucidal activity of formaldehyde was not assessable, due to its high cytotoxicity. Our results showed that cleaning is particularly important, because removal of the soiling provides improved effectiveness of the tested chemical compounds.
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