The African swine fever epidemic occurred in Poland at the beginning of 2014 and, up to date, the disease has been spreading mainly in the eastern part of the country. Unexpectedly, in November 2019 an infected wild boar case was confirmed in Lubuskie voivodship in western Poland. During the following weeks, several dozen African swine fever virus (ASFV)-positive animals were notified in the neighboring area, causing severe concern regarding further spread of the disease to the mostly pig-dense region in Poland, namely, Wielkopolskie voivodship. Moreover, almost a year after, several infected wild boar cases were confirmed for the first time in Germany, just beyond the Polish border, sending out a shock wave through the global pig market. The whole genome sequence of ASFV, isolated from the first case of ASF in western Poland, and three selected viruses from other affected areas, revealed the tandem repeat and single nucleotide polymorphism (SNP) variations in reference to the Georgia 2007/1 strain. These data, supported by the conventional sequencing of selected genomic regions from a total of 154 virus samples isolated between 2017 and 2020 in Poland, shed a new light on pathogen epidemiology. The sequence variations within the O174L gene detected in this study showed that cases identified in western Poland might be originating from the so-called southern Warsaw cluster. Moreover, the viruses originating from the northern Warsaw cluster do not possess single nucleotide polymorphism (SNP) mutations within the K145R and MGF 505-5R genes, which are specific to all of the other Polish ASFV strains. These results led to a conclusion of their distinct origin. Supporting these results, the nucleotide sequencing of I73R/I329L intergenic region revealed its new, previously undescribed variant, called IGR IV, with an additional three tandem repeats of 10 nucleotides in comparison to the reference sequence of the Georgia 2007/1 strain.

African swine fever is a contagious disease, affecting pigs and wild boars, which poses a major threat to the pig industry worldwide and, therefore, to the agricultural economies of many countries. Despite intensive studies, an effective vaccine against the disease has not yet been developed. Since 2007, ASFV has been circulating in Eastern and Central Europe, covering an increasingly large area. As of 2018, the disease is additionally spreading at an unprecedented scale in Southeast Asia, nearly ruining China’s pig-producing sector and generating economic losses of approximately USD 111.2 billion in 2019. ASFV’s high resistance to environmental conditions, together with the lack of an approved vaccine, plays a key role in the spread of the disease. Therefore, the biosecurity and disinfection of pig farms are the only effective tools through which to prevent ASFV from entering the farms. The selection of a disinfectant, with research-proven efficacy and proper use, taking into account environmental conditions, exposure time, pH range, and temperature, plays a crucial role in the disinfection process. Despite the significant importance of ASF epizootics, little information is available on the effectiveness of different disinfectants against ASFV. In this review, we have compiled the current knowledge on the transmission, spread, and control of ASF using the principles of biosecurity, with particular attention to disinfection, including a perspective based on Polish experience with ASF control.

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.

African swine fever (ASF), caused by African swine fever virus (ASFV), is currently one of the most important and serious diseases of pigs, mainly due to the enormous sanitary and socio-economic consequences. It leads to serious economic losses, not only because of the near 100% mortality rate, but also through the prohibitions of pork exports it triggers. Currently neither vaccines nor safe and effective chemotherapeutic agents are available against ASFV. The disease is controlled by culling infected pigs and maintaining high biosecurity standards, which principally relies on disinfection. Some countries have approved and/or authorised a list of biocides effective against this virus. This article is focused on the characteristics of chemical substances present in the most popular disinfectants of potential use against ASFV. Despite some of them being approved and tested, it seems necessary to perform tests directly on ASFV to ensure maximum effectiveness of the disinfectants in preventing the spread of ASF in the future.

This paper was aimed to characterize clinical signs and pathomorphological lesions in twenty-two pigs, infected intranasally by different doses of African swine fever virus (Pol18_28298_O111), isolated during the outbreak in a pig farm that occurred in Eastern Poland throughout 2018. This article also attempts to indicate risk, related to virus load and shedding, and present possible difficulties with proper disease recognition at the farm level. The results revealed that even a very low dose (5 HAU) may initiate the infection. Various forms of the disease (acute, subacute, and chronic), mainly with prodromal clinical signs like fever, apathy, and reduced feed intake were observed. The most frequently observed lesions (82%) were: hyperemia and enlargement of lymph nodes and splenomegaly. The minimal incubation period was estimated at five days post-infection (dpi). Mortality ranged from 80–100%. Two pigs survived the infection. Some viremic animals presented delayed fever. In some cases, the fever was not detectable. Shortly after viremia, the virus was secreted ion the urine, feces, and saliva. The highest levels of virus were found in the internal organs and blood; however in the case of one pig (chronic form), viral DNA was not detected in the spleen, liver, bone marrow, and brain. Veterinary diagnosis may be difficult, and the final results should always be based on laboratory investigations.

Four commercial disinfectants were chosen for being generally accepted as effective against ASFV. Only two of them, based on sodium hypochlorite and potassium peroxymonosulfate, confirmed their effectiveness in selected concentrations. Taken together, our data supports the effectivenes of chemical disinfectants containing sodium hypochlorite (1%, 0.5% in low level soiling) and potassium peroxymonosulfate (1% in high level soiling). Furthermore, these results highlight the importance of pre-cleaning steps to remove soiling before proper disinfection which improves the effectiveness of tested disinfectants.