Molecular detection and phylogenetic analysis of porcine circovirus type 3 in 21 Provinces of China during 2015–2017

The emerging Porcine circovirus type 3 (PCV3) is associated with porcine dermatitis and nephropathy syndrome, reproductive failure and cardiac and multisystemic inflammation. To trace the prevalence and evolution of PCV3 in pigs with respiratory diseases or digestive diseases in China, 616 samples were collected from 21 provinces or municipalities of China from 2015 to 2017. All samples were analysed with PCR and a cap‐gene‐based phylogeny. The results indicated that the positive rate of PCV3 was 12.2% (75/616) at the sample level; 24.1% (42/174) at the farm level; 10.4% (50/480) in the digestive‐disease‐affected samples; 26.6% (25/94) in the respiratory‐disease‐affected samples; all 42 healthy samples were negative for PCV3. A statistical analysis showed that PCV3 infection was closely associated with both digestive diseases (p < 0.05) and respiratory diseases (p < 0.01). A sequence analysis revealed that the cap genes of the 51 PCV3 strains identified in our study shared nucleotide homologies of 97.2%–100% and amino acid homologies of 96.3%–100%. A total of 17 amino acid mutations were observed among the Cap proteins of the 51 PCV3 strains, of which R¹⁰/K, A²⁴/V, R²⁷/K, T⁷⁷/S, F¹⁰⁴/Y, I¹⁵⁰/L are mutations among worldwide strains. A phylogenetic analysis demonstrated that the 51 PCV3 strains formed three clades, including PCV3a (15/51, 29.4%), PCV3b (21/51, 41.2%) and PCV3c (15/51, 29.4%). These data provide evidence that PCV3 exhibits high prevalence and genetic diversity and is associated with digestive diseases and respiratory diseases in pig.     

Presence of Torque teno sus virus 1 and 2 in porcine circovirus 3‐positive pigs

In this study, the co‐infection of Torque teno sus virus (TTS uV) and porcine circovirus type 3 (PCV 3) was reported. One hundred and ten of 132 (83.3%) PCV 3‐positive samples were co‐infected with Torque teno sus virus 1 (TTS uV1). Ninety‐four of 132 (71.2%) PCV 3‐positive samples were co‐infected with Torque teno sus virus 2 (TTS uV2). Sixty‐six of 132 (50.0%) of PCV 3‐positive samples were co‐infected with both TTS uV1 and TTS uV2. There were no clinical signs of infection in pigs that were both PCV 3‐positive and PCV 2‐negative, in either multiparous sows or live‐born infants. The high co‐infection rate provides valuable information for the further study of the pathological correlation between PCV 3 and TTS uVs.     

Development of a chemiluminescence immunoassay using recombinant non‐structural epitope‐based proteins to accurately differentiate foot‐and‐mouth disease virus‐infected and vaccinated bovines

The contamination of inactivated vaccine with non‐structural proteins (NSP s) leads to a high false‐positive rate, which is a substantial barrier to accurately differentiate foot‐and‐mouth disease virus (FMDV )‐infected animals from vaccinated animals. To address this problem, a new chemiluminescence immunoassay (CLIA ) method was developed to detect antibodies targeting the two recombinant epitope‐based proteins located in 3A and 3B. The 3Aepitp‐3Bepitp CLIA exhibited a diagnostic sensitivity of 94.0% and a diagnostic specificity of 97.5% for the detection of serum samples (naïve bovines, n  = 52, vaccinated bovines, n  = 422, infected bovines, n  = 116) from animals with known status. The CLIA method also had a concordance rate of 88.1% with the PrioCHECK FMDV NSP ELISA based on the detection of 270 serum samples from the field. Importantly, the 3Aepitp‐3Bepitp CLIA produced no false‐positives when used to detect FMDV in samples from bovines that had been vaccinated up to five times, and it was demonstrated a low false‐positive rate when the bovines had been vaccinated up to ten (2.15%) and fifteen times (5.93%). Therefore, the 3Aepitp‐3Bepitp CLIA detects FMDV in samples from frequently vaccinated bovines with high accuracy and represents an alternative method to differentiate FMDV ‐infected and vaccinated bovines.     

First detection of porcine circovirus type 3 on commercial pig farms in Poland

Porcine circovirus type 3 (PCV3) is a novel circovirus species recently discovered in USA and China in cases of porcine dermatitis and nephropathy syndrome, reproductive failure, respiratory disease and multisystemic inflammation. This study reports on the first identification of PCV3 in Europe, in serum from pigs from Polish farms. A total of 1,050 serum samples were collected between 2014 and 2017 from sows and 3–20 weeks old pigs from 14 commercial farms representing different regions of Poland, different size and health status. The samples were pooled by 4–6 and tested with real‐time PCR for PCV3. PCV3 DNA was detected in 12 of 14 farms (85.7%). On the PCV3‐positive farms, the virus was detected in 5.9% to 65% serum pools. PCV3 was most common among weaned pigs and finishers (26.1% and 28.0% of serum pools, respectively). Sequence analysis of 359 nucleotide fragment of ORF2 showed highest identity of 99.7% to PCV3‐US/SD2016 from USA. Our results indicate that PCV3 is a common virus among Polish pigs but no links to unexplained disease conditions were established.     

Rapid specific and visible detection of porcine circovirus type 3 using loop‐mediated isothermal amplification (LAMP)

In this study, a rapid and specific assay for the detection of porcine circovirus type 3 (PCV 3) was established using loop‐mediated isothermal amplification (LAMP ). Four primers were specifically designed to amplify PCV 3. The LAMP assay was effectively optimized to amplify PCV 3 by water bath at 60°C for 60 min. The detection limit was approximately 1 × 10¹ copy in this LAMP assay. Compared to porcine circovirus type 2 (PCV 2), both gE and gD genes of pseudorabies virus (PRV ) and porcine parvovirus (PPV ), the LAMP assay showed a high specific detection of PCV 3. A visible detection method was developed using SYBR Green I to recognize the results rapidly. Based on the detection of 20 clinical tissue samples, the LAMP assay was more practical and convenient than classical PCR due to its simplicity, high sensitivity, rapidity, specificity, visibility and cost efficiency.     

Porcine circovirus 3 is highly prevalent in serum and tissues and may persistently infect wild boar (Sus scrofa scrofa)

Porcine circovirus 3 (PCV‐3) prevalence has been minimally investigated in wild boar; dynamics of infection and viral tissue distribution are currently unknown. In this study, serum samples from 518 wild boar (from years 2004 to 2018) were used to study frequency of infection. Also, serum samples from 19 boar captured and recaptured at least two times for a period of time from 1 month to 1 year were collected to determine PCV‐3 infection dynamics. Finally, to elucidate PCV‐3 DNA organic distribution, sera, different tissues and faeces were obtained from 35 additional wild boar. PCV‐3 DNA was extracted and amplified with a conventional PCR. For the PCV‐3 PCR‐positive sera from the longitudinally sampled and different tissue types, a quantitative PCR was performed. Genome sequence was obtained from a number of PCV‐3 PCR‐positive samples from different years, different time‐points of infection and tissues. Obtained results confirmed the susceptibility of wild boar to the virus, showing high frequency of PCV‐3 detection (221 out of 518, 42.66%) and demonstrating circulation at least since 2004. Compiled data indicate the possibility of long‐term infections, since 5 out of 10 PCV‐3 PCR‐positive boars longitudinally sampled showed positivity in samplings separated for more than 5 months. All tested tissue types’ harboured PCV‐3 genome, with the highest percentage of PCR positivity in submandibular lymph node, tonsil, lung, liver, spleen and kidney. The amount of DNA in all tested PCV‐3 PCR‐positive samples was moderate to low. All partial and complete PCV‐3 sequences obtained from wild boar displayed high nucleotide identity, higher than 98%. In conclusion, this study further confirms that wild boar is susceptible to PCV‐3 infection, showing high frequency of detection in this animal species. Furthermore, PCV‐3 can be found in different tissues of wild boar and is apparently able to cause persistent infection.     

Serological Survey of Porcine circovirus‐2 in Captive Wild Boars (Sus scrofa) from Registered Farms of South and South‐east Regions of Brazil

This study aimed to survey captive wild boars for antibodies against Porcine circovirus‐2 (PCV‐2) in registered farms. Serum samples (n = 1305) were collected from 90‐day‐old wild boars from 118 farms of the Brazilian South‐east region, including the states of Minas Gerais and São Paulo, and South region, including the states of Paraná, Rio Grande do Sul and Santa Catarina. All herds (100%) presented reactive animals, in varying numbers and from low‐to‐high antibody titres, with the occurrence ranging from 82 to 89%. Considering farms, the average prevalence was of 84.9% (P < 0.05) and ranged from 54.1 to 94.95%. Regarding the geographic regions studied, the prevalence was of 100%, with PCV2 antibodies detected in wild boars of all regions. This study provides the first evidence of PCV2 antibodies in captive wild boars in Brazil.     

Retrospective detection of Porcine circovirus 3 (PCV‐3) in pig serum samples from Spain

Porcine circovirus 3 (PCV ‐3) is an emerging circovirus species that has recently been reported in different countries around the world, suggesting a widespread circulation. In this study, sera samples originating from 654 pigs of different production phases and clinical/pathological conditions, submitted for diagnostic purposes between 1996 and 2017, were randomly selected. Detection of PCV ‐3 genome in such samples was attempted with a previously described PCR method, and the partial genome sequence was obtained from selected PCV ‐3‐positive samples from different years. Compiled data confirmed that PCV ‐3 has been circulating in the Spanish pig population since 1996. The overall frequency of PCV ‐3 PCR ‐positive samples in the study period was 11.47% (75 of 654). Phylogenetic analysis of twelve PCV ‐3 partial sequences obtained showed a high nucleotide identity with the already known PCV ‐3 sequences, with minor variations among years. No significant correlation was found between the detection of PCV ‐3 and any production phase nor clinical/pathological condition. These results confirm PCV ‐3 circulation at least since 1996 in the Spanish pig population with a low/moderate frequency. Although the information obtained was limited, PCV ‐3 did not appear to be linked to any specific pathological condition or age group.     

Drastic decline of hepatitis E virus detection in domestic pigs after the age of 6 months,Corsica, France

Suidae is an important reservoir of hepatitis E virus (HEV) and a source of transmission to humans (direct contact or via consumption of meat products). Our goal was to characterize the epidemiology of HEV infecting domestic pigs in Corsica Island, a French region hyperendemic for HEV. In Corsica, traditional extensive (or semi‐extensive) outdoor pig farming system is common. Sixteen farms were selected according to location and breeding system. Individual pig faeces samples were collected and qRT‐PCR for detecting HEV RNA was performed. Nucleic acids from HEV‐positive samples were amplified using specific ORF2 genotyping system. The genotype and subtype of the Corsican HEV sequences were determined by phylogenetic analysis. Among the 919 porcine faeces samples tested 9.2% (n = 85) were positive. The presence of viral RNA was correlated with (a) age (>6 months) Adjusted Odd Ratio (AOR) 0.25 [0.068–0.90] p = .032; 3–4 months AOR = 4.94 [2.30–10.62] p = .000043) with the logistic regression model with a random effect at the farm level. Among the 85 positive samples, 83 belonged to genotype 3c and two to genotype 3f. The highest prevalence was observed in the 3–4 months age group and older age (>6 months) was negatively related to HEV infection and this suggests that traditional breeding with a late slaughter age may limit the risk of transmission to humans. A kinetic study of pigs from birth to slaughtering would allow to ensure that the type of traditional breeding reported here is very favourable to the absence of the virus in slaughtered pigs and in pork products.     

Detection of Capripoxvirus DNA Using a Field‐Ready Nucleic Acid Extraction and Real‐Time PCR Platform

Capripoxviruses, comprising sheep pox virus, goat pox virus and lumpy skin disease virus cause serious diseases of domesticated ruminants, notifiable to The World Organization for Animal Health. This report describes the evaluation of a mobile diagnostic system (Enigma Field Laboratory) that performs automated sequential steps for nucleic acid extraction and real‐time PCR to detect capripoxvirus DNA within laboratory and endemic field settings. To prepare stable reagents that could be deployed into field settings, lyophilized reagents were used that employed an established diagnostic PCR assay. These stabilized reagents demonstrated an analytical sensitivity that was equivalent, or greater than the established laboratory‐based PCR test which utilizes wet reagents, and the limit of detection for the complete assay pipeline was approximately one log₁₀ more sensitive than the laboratory‐based PCR assay. Concordant results were generated when the mobile PCR system was compared to the laboratory‐based PCR using samples collected from Africa, Asia and Europe (n = 10) and experimental studies (n = 9) representing clinical cases of sheep pox, goat pox and lumpy skin disease. Furthermore, this mobile assay reported positive results in situ using specimens that were collected from a dairy cow in Morogoro, Tanzania, which was exhibiting clinical signs of lumpy skin disease. These data support the use of mobile PCR systems for the rapid and sensitive detection of capripoxvirus DNA in endemic field settings.     

Senecavirus A: An Emerging Vesicular Infection in Brazilian Pig Herds

Vesicular diseases are clinically and economically important infections that affect farm animals. North American studies have suggested that Senecavirus A infection might be associated with a vesicular disease in pigs known as porcine idiopathic vesicular disease (PIVD). In the beginning of 2015, outbreaks of porcine vesicular disease have occurred in six Brazilian states from three geographical regions. Official diagnostic tests were performed with negative results for classical vesicular diseases of compulsory reporting. This study investigated Senecavirus A infection in PIVD outbreaks in which other aetiological agents were ruled out. A primer set was designed to amplify a 542‐bp product size of VP3/VP1 region of Senecavirus A genome in RT‐PCR assay. Primer specificity was analysed in silico and in porcine biological specimens. For this, clinical specimens were collected from eight pig herds affected with PIVD, including vesicular fluid (n = 4) and swabs (n = 7) and scrapings of ruptured vesicles and ulcerative lesions (n = 5) from weaned and adult pigs. Clinically healthy animals (n = 52) of PIVD‐affected and non‐affected pig herds also were evaluated for Senecavirus A infection. The 16 samples from PIVD‐affected animals were positive for Senecavirus A in the RT‐PCR assay, while none of the clinically healthy pigs were detected with the virus. Sequencing analysis revealed high nucleotide (87.6–98.5%) and amino acid (95–99.4%) similarities to SVV‐01 prototype and other Senecavirus A strains from North American pigs. Primer set presented herein was suitable for molecular characterization of Senecavirus A. The results suggest that Senecavirus A was the aetiological agent of the vesicular disease outbreaks in the evaluated pig herds. This is the first study to report the Senecavirus A infection in clinically affected pigs outside of North America. Senecavirus A was considered a novel emerging pathogen associated with an important vesicular disease in Brazil.     

The prevalence of novel porcine circovirus type 3 isolates in pig farms in China

The emerging porcine circovirus type 3 (PCV3) has been reported in Chinese swine herds since 2017. We performed a nationwide investigation on the prevalence of PCV3 in pig breeding farms and slaughterhouses in China. A total of 4,040 tonsil samples were collected from 89 farms in 25 provinces, and 1,419 lymph node samples were collected from 50 slaughterhouses in 27 provinces. The PCR results showed that in pig breeding farms, the positive rate was 41.6% (37/89) at the farm level and 5.0% (201/4040) at the individual level. In the slaughterhouses, the positive rate was 62.0% (31/50) at the farm level and 8.0% (114/1419) at the individual level. The PCR‐positive samples were further sequenced, and 19 new PCV3 isolates were identified. The complete genomes of the 19 virus isolates showed 97.4%–99.7% nucleotide identity with other PCV3 isolates. The phylogenetic analysis revealed that the 19 isolates were divided into PCV3a and PCV3b genotype clusters based on the PCV3 complete genome sequences. This study indicated that PCV3 has spread extensively in both pig breeding farms and slaughterhouses. The positive rate of PCV3 was higher in eastern China compared to other regions in China. Furthermore, this study will help us understand the prevalence and genetic variation of PCV3 in Chinese swine herds.     

Post‐transplant lymphoproliferative disorders with naso‐ and oropharyngeal manifestation

The nasopharyngeal/oropharyngeal lymphatic tissues represent the anatomical site of Epstein–Barr virus (EBV) entry. Post‐transplant lymphoproliferative disorders (PTLD) are often associated with EBV, but little is known about the characteristics of nasopharyngeal/oropharyngeal mass‐forming PTLD. Retrospective evaluation of our own PTLD database (n = 79) and the PubMed^® database (n = 61) has been performed. Sinonasal/oro‐/nasopharyngeal lymphatic masses were early lesions (n = 54/140, 38.5%), polymorphic PTLD (n = 32/140, 23%), monomorphic B‐PTLD (n = 47/140, 33.5%) and T‐PTLD (n = 7/140, 5%). One‐fourth of lesions manifested as masses in the Waldeyer's ring, and in two‐thirds of cases, swelling of tonsils was related to manifestation of benign early lesions. Tonsil infiltration by polymorphic PTLD and monomorphic PTLD was present in one‐third of cases. Extratonsillar masses were mainly monomorphic PTLD. Meta‐analysis of our data in combination with previously published data revealed that lung transplantation and young patients are at a higher risk for earlier manifestation of monomorphic PTLD. Therapy is similar to PTLD therapy strategies, in general reduced immunosuppression and chemotherapy for polymorphic and monomorphic PTLD, and diagnostic and therapeutic surgical gross tumour resection of tonsillar/adenoid lesions. In summary, it is relevant for the clinical differential diagnosis that oro‐/nasopharyngeal aggressive PTLD manifested in ~30% as tonsillar masses and >90% at extratonsillar sites.     

Early Detection of Foot‐And‐Mouth Disease Virus from Infected Cattle Using A Dry Filter Air Sampling System

Foot‐and‐mouth disease (FMD) is a highly contagious livestock disease of high economic impact. Early detection of FMD virus (FMDV) is fundamental for rapid outbreak control. Air sampling collection has been demonstrated as a useful technique for detection of FMDV RNA in infected animals, related to the aerogenous nature of the virus. In the current study, air from rooms housing individual (n = 17) or two groups (n = 4) of cattle experimentally infected with FDMV A24 Cruzeiro of different virulence levels was sampled to assess the feasibility of applying air sampling as a non‐invasive, screening tool to identify sources of FMDV infection. Detection of FMDV RNA in air was compared with first detection of clinical signs and FMDV RNA levels in serum and oral fluid. FMDV RNA was detected in room air samples 1–3 days prior (seven animals) or on the same day (four animals) as the appearance of clinical signs in 11 of 12 individually housed cattle. Only in one case clinical signs preceded detection in air samples by one day. Overall, viral RNA in oral fluid or serum preceded detection in air samples by 1–2 days. Six individually housed animals inoculated with attenuated strains did not show clinical signs, but virus was detected in air in one of these cases 3 days prior to first detection in oral fluid. In groups of four cattle housed together, air detection always preceded appearance of clinical signs by 1–2 days and coincided more often with viral shedding in oral fluid than virus in blood. These data confirm that air sampling is an effective non‐invasive screening method for detecting FMDV infection in confined to enclosed spaces (e.g. auction barns, milking parlours). This technology could be a useful tool as part of a surveillance strategy during FMD prevention, control or eradication efforts.     

Seminal plasma miR‐210‐3p is a biomarker for screening dyszoospermia caused by varicocele

To evaluate the value of seminal plasma miR‐210‐3p as a novel and non‐invasive biomarker for screening dyszoospermia caused by varicocele. Semen samples from patients with varicocele and healthy males were collected for semen analysis and quantitative real‐time polymerase chain reaction. Cox univariate and multivariate analysis and receiver operating characteristic curve analysis were used to assess the relationship between the level of seminal plasma miR‐210‐3p and impaired spermatogenic function. Our results showed that the level of seminal plasma miR‐210‐3p in the varicocele patients was 2.18 times that of the control group (p < 0.001), and its expression increased significantly with the severity of varicocele. Compared with preoperative, the expression of seminal plasma miR‐210‐3p declined significantly at 3 months after surgery. Cox univariate and multivariate analysis showed that seminal plasma miR‐210‐3p (p = 0.02), bilateral varicocele (p = 0.04) and the grade 3 varicocele (p = 0.03) were significantly and independently associated with dyszoospermia caused by varicocele. Our results suggest that seminal plasma miR‐210‐3p is a useful clinical biomarker for screening dyszoospermia caused by varicocele, and this is the key to deciding early effective treatment and protecting the fertility of the patients.     

Detection and phylogenetic analysis of porcine circovirus type 3 in central China

Porcine circovirus type 3 (PCV3) is the pathogen responsible for a new infectious disease that was first reported in 2016 in the United States. To further investigate the epidemic profile and genetic diversity of the virus, one hundred and seventy clinical samples (110 tissue samples and 60 serum samples) were collected from 41 different pig farms in 14 cities in central China, and a SYBR Green I‐based quantitative real‐time PCR method was developed to detect PCV3. The partial cap genes of four field strains from four different farms were sequenced and analysed. The results showed the detection limit was 2.19 × 10¹ genome copies/μl. Fifty‐three of 170 samples were detected as positive for PCV3, giving a PCV3‐positive rate of 31.18%, with 48.78% (20/41) of pig farms harbouring PCV3, which varied from 20% to 42.86% between 2013 and 2017. PCV3 could be detected in samples from pigs with different clinical presentations, and the PCV3‐positive rates varied for these different clinical presentations. The partial capsid genes of four PCV3 strains (designated YZ, LY‐03, NY and SP) shared 96.3%–99.4% nucleotide identity with those available in GenBank. Phylogenetic analysis based on the capsid gene of 32 PCV3 strains showed that the four PCV3 strains in this study were clustered with the China/GD2016 and South Korea Ku‐1606 strains. The results of this study will aid our understanding of the molecular epidemiology of PCV3.     

Study on testicular response to prolong artemisinin‐based combination therapy treatments in guinea pigs

Artemisinin‐based combination therapies (ACTs) are first‐line agents in malaria chemotherapy, but often abused in malaria endemic countries including Nigeria. This study investigated the effects of prolong treatment of artesunate–amodiaquine (ATS–Amod), artesunate‐sulfadoxine‐pyrimethamine (ATS–SP) and artemether–lumefantrine (ATM–Lum) on testicular indices in guinea pigs. Sixty‐five pigs were grouped into 13 (n = 5 per group). Six groups were given standard or double therapeutic dose equivalents of ATS–Amod, ATS‐SP or ATM–Lum daily for 14 day and sacrificed 24 hr after treatments. Six other groups (recovery groups) received similar drug treatments but allowed to recover for 14 day before sacrificed. Control group received distilled water. ATS–Amod, ATS–SP and ATM–Lum, respectively, decreased (p < .01) sperm count (17.7%, 37.7% and 33.8%), motility (48.6%, 50% and 51.4%), viability (32.7%, 43.7% and 35.9%) and morphology (123.5%, 0% and 0%), compared to control. These effects were reversed in recovery animals. Also, they decreased (p < .01) luteinising hormone and testosterone serum levels, without affecting follicle‐stimulating hormone. Testicular malondialdehyde level was elevated, and glutathione was decreased, while catalase and superoxide dismutase enzymes were unaffected by the drugs. The alterations were all reversed in recovery animals. The study reveals that prolong administration of ACTs results in reversible alteration of sperm parameters and reduction of testosterone which is partly attributable to oxidative stress.     

Co‐localization of Middle East respiratory syndrome coronavirus (MERS‐CoV) and dipeptidyl peptidase‐4 in the respiratory tract and lymphoid tissues of pigs and llamas

This study investigated the co‐localization of the Middle East respiratory syndrome coronavirus (MERS‐CoV) and its receptor dipeptidyl peptidase‐4 (DPP4) by immunohistochemistry (IHC) across respiratory and lymphoid organs of experimentally MERS‐CoV infected pigs and llamas. Also, scanning electron microscopy was performed to assess the ciliary integrity of respiratory epithelial cells in both species. In pigs, on day 2 post‐inoculation (p.i.), DPP4‐MERS‐CoV co‐localization was detected in medial turbinate epithelium. On day 4 p.i., the virus/receptor co‐localized in frontal and medial turbinate epithelial cells in pigs, and epithelial cells distributed unevenly through the whole nasal cavity and in the cervical lymph node in llamas. MERS‐CoV viral nucleocapsid was mainly detected in upper respiratory tract sites on days 2 and 4 p.i. in pigs and day 4 p.i. in llamas. No MERS‐CoV was detected on day 24 p.i. in any tissue by IHC. While pigs showed severe ciliary loss in the nasal mucosa both on days 2 and 4 p.i. and moderate loss in the trachea on days 4 and 24 p.i., ciliation of respiratory organs in llamas was not significantly affected. Obtained data confirm the role of DPP4 for MERS‐CoV entry in respiratory epithelial cells of llamas. Notably, several nasal epithelial cells in pigs were found to express viral antigen but not DPP4, suggesting the possible existence of other molecule/s facilitating virus entry or down regulation of DPP4 upon infection.     

Surveillance and control of African Swine Fever in free‐ranging pigs in Sardinia

African swine fever (ASF) is a notifiable infectious disease, caused by the ASF virus (ASFV), which is a DNA virus belonging to the family Asfarviridae, genus Asfivirus. This disease has gained importance in the last decade after its spread in several countries in Eastern and Central Europe, and more recently, in China. Despite the efforts made to eradicate it, ASF is still present on the Mediterranean island of Sardinia (Italy) and has been since 1978. ASF risk factors on the island have been analysed in previous studies; the role of free‐ranging pigs in virus persistence has been suggested, but has not been fully elucidated. The most recent eradication plan provides more stringent measures to combat free‐ranging pigs and any kind of illegality in the pig sector. From December 2017 to June 2018, a total of 29 depopulation actions were performed in 13 municipalities in central Sardinia, during which 2,281 free‐ranging pigs were culled and more than 50% of them were tested for ASFV and antibody presence (1,218 and 1,416, respectively). A total of 651 pigs were seropositive, with a mean seroprevalence of 53.4% (CI 95% = 50.6–56.3), and 38 were ASFV positive (virus prevalence = 2.6%; CI 95% = 2.1–3.0). To the best of our knowledge, the present study is the first to provide a complete evaluation of this millennial system of pig farming and ASFV prevalence in free‐ranging pigs. Furthermore, it has emphasised the necessity of combining the maintenance of an epidemiological surveillance program with continuous education of farmers and other people involved in pig husbandry, based on cultural and economic aspects.