Passive Surveillance as a Key Tool for African Swine Fever Eradication in Wild Boar: A Protocol to Find Carcasses Tested and Validated in the Mediterranean Island of Sardinia

African swine fever (ASF) is one of the most important and serious contagious hemorrhagic viral diseases affecting domestic pigs and wild boar and is associated with high mortality rates while also having an extensive sanitary and socioeconomic impact on the international trade of animal and swine products. The early detection of the disease is often hampered by inadequate surveillance. Among the surveillance strategies used, passive surveillance of wild boars is considered the most effective method for controlling the African swine fever virus (ASFV). Otherwise, the design of a sufficiently sensitive ASF surveillance system requires a solid understanding of the epidemiology related to the local eco-social context, especially in the absence of virus detection. Even if the number of carcasses needed to demonstrate ASF eradication has been established, the scientific context lacks detail compared to protocols applied in the active search for wild boar carcasses. The aim of this study was to describe the protocol applied in the active search for carcasses, providing detailed information on the number of people and dogs as well as the amount of time and space used within the Mediterranean area. Using a specific tool developed to record, trace, and share field data (the GAIA observer app), a total of 33 active searches for wild boar carcasses were organized during 2021-2023. Most of these searches were planned to find carcasses that had previously been reported by hunters. A total of 24 carcasses were found, with only 2 carcasses not previously reported. The final protocol applied involved four people, with an average speed of 1.5 km/h. When a carcass had been previously reported, about 2 km of distance had to be covered in about 1.5 h to find the carcass, and even less time was spent when a dog (untrained) was present. In conclusion, it can be stated that, when searching for carcasses, solid collaboration with local hunters or other forest visitors is necessary to ensure carcasses are reported. The process involves small groups of experts actively searching for carcasses, possibly with the use of hunting dogs without special training. The data presented could be of valid support for those countries characterized by Mediterranean vegetation that are faced with the need to plan active carcass searches.

Virulence genes identification in Salmonella enterica isolates from humans, crocodiles, and poultry farms from two regions in Colombia

Background and Aim

Salmonella spp. is frequently found in the digestive tract of birds and reptiles and transmitted to humans through food. Salmonellosis is a public health problem because of pathogenicity variability in strains for virulence factors. This study aimed to identify the virulence genes in Salmonella isolates from humans, crocodiles, broiler cloacas, and broiler carcasses from two departments of Colombia.

Materials and Methods

This study was conducted on 31 Salmonella enterica strains from humans with gastroenteritis (seven), crocodiles (seven), broiler cloacas (six), and broiler carcasses (12) from Tolima and Santander departments of Colombia, belonging to 21 serotypes. All samples were tested for Salmonella spp. using culture method on selective and non-selective mediums. Extraction of genomic DNA was performed from fresh colonies, DNA quality was verified by spectrophotometry and confirmed by amplification of InvA gene using conventional polymerase chain reaction (PCR). bapA, fimA, icmF, IroB, marT, mgtC, nlpI, oafA, pagN, siiD, spvC, spvR, spvB, Stn, and vexA genes were amplified by PCR.

Results

The most prevalent gene was bapA (100%), followed by marT (96.77%), mgtC (93.55%), and fimA (83.87%). Likewise, IroB (70.97%), Stn (67.74%), spvR (61.29%), pagN (54.84%), icmF (54.8%), and SiiD (45.16%) were positive for more than 50% of the strains. Furthermore, none of the isolates tested positive for the vexA gene. Salmonella isolates presented 26 virulence profiles.

Conclusion

This study reported 14 virulence genes in Salmonella spp. isolates from humans with gastroenteritis, crocodiles, and broiler cloacas and carcasses. The distribution of virulence genes differed among sources. This study could help in decision-making by health and sanitary authorities.

Filter sterilized carcass rinsate for recovery of Salmonella species with various concentrations of cetylpyridinium chloride

Controlling Salmonella in poultry processing continues to be important to processors and consumers. Cetylpyridinium chloride (CPC) has proven to be effective in vitro in controlling Salmonella. This study evaluated the recovery of Salmonella after overnight storage in 4°C filter-sterilized carcass rinsate containing CPC from 0.44 to 909 ppm (μg/mL). Ten Salmonella serotypes (18 strains), of which 6 serotypes are commonly isolated from poultry products, were grown in Bacto-Tryptic Soy Broth overnight at 37°C. Serial dilutions of a CPC/propylene glycol solution were prepared in 24-well tissue culture plates containing filter-sterilized carcass rinsate. Approximately 107 cfu/mL of each Salmonella serotype was added to the appropriate wells. Inoculated plates were stored overnight at 4°C. After storage, triplicate plates of brilliant green agar with sulfapyridine (BGS) were surface inoculated with 10 μL of the contents for each well, streaked for isolation, and incubated at 37°C for 24 h. Three replications were conducted. The presence of typical colonies on BGS plates was recorded as growth and verified through biochemical and serological testing. Of the serotypes chosen, Salmonella Kentucky, Dublin, and Enteritidis were the least resistant to CPC with a median minimum inhibitory concentration (MIC) of 14.22 μg/mL (range from 3.55 to 56.88 μg/mL); S. Typhimurium demonstrated a median MIC of 114.00 μg/mL (range from 28.44 to 114.00 μg/mL). Residual CPC potentially remaining attached to a carcass or in the weep after processing could potentially alter which Salmonella serotype is recovered from a carcass rinse due to different growth patterns during regulatory testing, with a potential for more virulent strains not to be recovered.

Estimating the Directional Spread of Epidemics in Their Early Stages Using a Simple Regression Approach: A Study on African Swine Fever in Northern Italy

The early identification of the spreading patterns of an epidemic infectious disease is an important first step towards the adoption of effective interventions. We developed a simple regression-based method to estimate the directional speed of a disease's spread, which can be easily applied with a limited dataset. We tested the method using simulation tools, then applied it on a real case study of an African Swine Fever (ASF) outbreak identified in late 2021 in northwestern Italy. Simulations showed that, when carcass detection rates were <0.1, the model produced negatively biased estimates of the ASF-affected area, with the average bias being about -10%. When detection rates were >0.1, the model produced asymptotically unbiased and progressively more predictable estimates. The model produced rather different estimates of ASF's spreading speed in different directions of northern Italy, with the average speed ranging from 33 to 90 m/day. The resulting ASF-infected areas of the outbreak were estimated to be 2216 km², about 80% bigger than the ones identified only thorough field-collected carcasses. Additionally, we estimated that the actual initial date of the ASF outbreak was 145 days earlier than the day of first notification. We recommend the use of this or similar inferential tools as a quick, initial way to assess an epidemic's patterns in its early stages and inform quick and timely management actions.

Estimation of R0 for the Spread of the First ASF Epidemic in Italy from Fresh Carcasses

After fifty years of spread in the European continent, the African swine fever (ASF) virus was detected for the first time in the north of Italy (Piedmont) in a wild boar carcass in December, 2021. During the first six months of the epidemic, the central role of wild boars in disease transmission was confirmed by more than 200 outbreaks, which occurred in two different areas declared as infected. The virus entered a domestic pig farm in the second temporal cluster identified in the center of the country (Lazio). Understanding ASF dynamics in wild boars is a prerequisite for preventing the spread, and for designing and applying effective surveillance and control plans. The aim of this work was to describe and evaluate the data collected during the first six months of the ASF epidemic in Italy, and to estimate the basic reproduction number (R0) in order to quantify the extent of disease spread. The R0 estimates were significantly different for the two spatio-temporal clusters of ASF in Italy, and they identified the two infected areas based on the time necessary for the number of cases to double (td) and on an exponential decay model. These results (R0 = 1.41 in Piedmont and 1.66 in Lazio) provide quantitative knowledge on the epidemiology of ASF in Italy. These parameters could represent a fundamental tool for modeling country-specific ASF transmission and for monitoring both the spread and sampling effort needed to detect the disease early.

Changes in Estimating the Wild Boar Carcasses Sampling Effort: Applying the EFSA ASF Exit Strategy by Means of the WBC-Counter Tool

African swine fever (ASF) is a devastating disease, resulting in the high mortality of domestic and wild pigs, spreading quickly around the world. Ensuring the prevention and early detection of the disease is even more crucial given the absence of licensed vaccines. As suggested by the European Commission, those countries which intend to provide evidence of freedom need to speed up passive surveillance of their wild boar populations. If this kind of surveillance is well-regulated in domestic pig farms, the country-specific activities to be put in place for wild populations need to be set based on wild boar density, hunting bags, the environment, and financial resources. Following the indications of the official EFSA opinion 2021, a practical interpretation of the strategy was implemented based on the failure probabilities of wrongly declaring the freedom of an area even if the disease is still present but undetected. This work aimed at providing a valid, applicative example of an exit strategy based on two different approaches: the first uses the wild boar density to estimate the number of carcasses need to complete the exit strategy, while the second estimates it from the number of wild boar hunted and tested. A practical free access tool, named WBC-Counter, was developed to automatically calculate the number of needed carcasses. The practical example was developed using the ASF data from Sardinia (Italian island). Sardinia is ASF endemic from 43 years, but the last ASFV detection dates back to 2019. The island is under consideration for ASF eradication declaration. The subsequent results provide a practical example for other countries in approaching the EFSA exit strategy in the best choices for its on-field application.

Evidence of absence regression: a binomial N-mixture model for estimating fatalities at wind energy facilities

Estimating bird and bat fatalities caused by wind-turbine facilities is challenging when carcasses are rare and produce counts that are either exactly or very near zero. The rarity of found carcasses is exacerbated when live members of a particular species are rare and when carcasses degrade quickly, are removed by scavengers, or are not detected by observers. With few observed carcass counts, common statistical methods like logistic, Poisson, or negative binomial regression are unreliable (statistically biased) and often fail to provide answers (i.e., fail to converge). Here, we propose a binomial N-mixture model that estimates fatality rates as well as the total number of carcasses when rates are expanded. Our model extends the "evidence of absence" model by relating carcass deposition rates to study covariates and by incorporating terms that naturally scale counts from facilities of different sizes. Our model, which we call Evidence of Absence Regression (EoAR), can estimate the total number of birds or bats killed at a single wind energy facility or a fleet of wind energy facilities based on covariate values. Furthermore, with accurate prior distributions the model's results are extremely robust to sparse data and unobserved combinations of covariate values. In this paper, we describe the model, show its low bias and high precision via computer simulation, and apply it to bat carcass counts observed at 21 wind energy facilities in Iowa.

Plague Transmission from Corpses and Carcasses

Knowing whether human corpses can transmit plague will inform policies for handling the bodies of those who have died of the disease. We analyzed the literature to evaluate risk for transmission of Yersinia pestis, the causative agent of plague, from human corpses and animal carcasses. Because we could not find direct evidence of transmission, we described a transmission pathway and assessed the potential for transmission at each step. We examined 3 potential sources of infection: body fluids of living plague patients, infected corpses and carcasses, and body fluids of infected corpses. We concluded that pneumonic plague can be transmitted by intensive handling of the corpse or carcass, presumably through the inhalation of respiratory droplets, and that bubonic plague can be transmitted by blood-to-blood contact with the body fluids of a corpse or carcass. These findings should inform precautions taken by those handling the bodies of persons or animals that died of plague.

Seasonal variability in non-consumptive mortality of Arctic zooplankton

Recent observations from high-latitude marine ecosystems indicate that non-consumptive mortality may be particularly high in Arctic zooplankton during the polar night. Here we have estimated the contribution of dead organisms to the mesozooplankton community in the high Arctic (Svalbard 78-81^oN) during the polar night (January), in spring (May) and in late summer (end of August). To identify in situ dead organisms, we used Neutral Red Stain. The dead zooplankton fraction consisted mainly of copepods, while the contribution of dead non-copepods was low in all seasons. The absolute abundance of dead copepods varied little between seasons; however, the relative contribution of dead copepods was highest in January with 11-35% of the copepods classified as dead, in contrast to 2-12% in spring and summer. Furthermore, there were species-specific differences: copepods of the genus Calanus contributed more to the dead fraction of the copepod community during the polar night compared to spring and summer, leading to a higher "dead" biomass in winter. We conclude that non-consumptive winter mortality is considerable in calanoid copepods in the Arctic and an important but so far neglected component of the passive carbon flux, providing carbon in larger portions for higher trophic level consumers during the low-productive winter.

Research objectives to fill knowledge gaps in African swine fever virus survival in the environment and carcasses, which could improve the control of African swine fever virus in wild boar populations

The European Commission requested that EFSA provide study designs for the investigation of four research domains according to major gaps in knowledge identified by EFSA in a report published in 2019: i) the patterns of seasonality of African Swine Fever (ASF) in wild boar and domestic pigs in the EU; ii) the epidemiology of ASF in wild boar; iii) survival of ASF virus (ASFV) in the environment and iv) transmission of ASFV by vectors. In this Scientific Opinion, the third research domain on ASFV survival is addressed. Nine research objectives were proposed by the working group and broader ASF expert networks, such as ASF stop, ENETWILD, VectorNet, AHAW network and the AHAW Panel Experts. Of the nine research objectives, only one was prioritised and elaborated into a general protocol/study design research proposal, pertaining ASFV survival in feed and bedding. To investigate the survival of ASFV in feed, bedding and roughage, laboratory survival studies are proposed. To investigate possible risk mitigation measures, proof-of-concept approaches should be investigated.

Nationwide Surveillance on Antimicrobial Resistance Profiles of Staphylococcus aureus Isolated from Major Food Animal Carcasses in South Korea During 2010-2018

Contamination of meat with antimicrobial-resistant bacteria represents a major public health threat worldwide. In this study, we determined the antimicrobial resistance profiles and resistance trends of Staphylococcus aureus isolated from major food animal carcasses (408 cattle, 1196 pig, and 1312 chicken carcass isolates) in Korea from 2010 to 2018. Approximately 75%, 92%, and 77% of cattle, pig, and chicken carcass isolates, respectively, were resistant to at least one antimicrobial agent. Resistance to penicillin (62.1%) was the highest, followed by resistance to tetracycline (42.1%) and erythromycin (28.2%). About 30% of pig and chicken isolates were resistant to ciprofloxacin. We observed linezolid resistance only in pig isolates (2.3%). However, all S. aureus isolates were sensitive to rifampin and vancomycin. We noted an increasing but fluctuating trend of kanamycin and penicillin resistance in cattle isolates. Similarly, the chloramphenicol, ciprofloxacin, tetracycline, and trimethoprim resistance rates were increased but fluctuated through time in pig isolates. Methicillin-resistant S. aureus (MRSA) accounted for 5%, 8%, and 9% of the cattle, pig, and chicken isolates, respectively. The MRSA strains exhibited significantly high resistance rates to most of the tested antimicrobials, including ciprofloxacin, erythromycin, and tetracycline compared with methicillin-susceptible S. aureus (MSSA) strains. Notably, a relatively high percentage of MRSA strains (5.2%) recovered from pig carcasses were resistant to linezolid compared with MSSA strains (2.1%). In addition, almost 37% of the isolates were multi-drug resistant. S. aureus isolates recovered from major food animal carcasses in Korea exhibited resistance to clinically important antimicrobials, posing a public health risk.

Assessing Campylobacter Colonization of Broiler Herds Ante Mortem and Monitoring Campylobacter Contamination Post Mortem by qPCR

Human campylobacteriosis is the most prevalent zoonosis, with chicken meat contributing substantially to the number of cases. Measures to avoid or at least reduce exposure by meat contaminated with Campylobacter (C.) spp. are needed. With regard to the process hygiene criterion introduced in 2018 for Campylobacter spp. on broiler carcasses, we evaluated the performance of a recently developed quantitative real-time PCR (qPCR) for C. jejuni/coli on random caecal samples and chicken meat. With the qPCR on pooled caecal samples not only C. jejuni/coli positive (69.6%) versus negative broiler herds (30.4%) were identified, but herds highly colonized with C. jejuni/coli (39.4%) could also be identified. From the chicken meat samples, 8.0% were positive for C. jejuni/coli by qPCR and 0.7% by enumeration (>10 cfu/g) compared to 58.3% using cultural enrichment. Given the higher sensitivity, the qPCR method could replace the currently used enumeration method to assess the process hygiene criterion for Campylobacter spp. on broiler carcasses. Moreover, with the qPCR, a reliable identification of C. jejuni/coli colonized incoming broiler herds a few days before slaughter is feasible, which provides important information to optimize slaughter processes. Finally, identifying and monitoring herds with high C. jejuni/coli colonization rates could help to individually improve biosecurity measures at farm level, eventually reducing the C. jejuni/coli load on chicken meat.

Salmonella spp. and Campylobacter spp. in poultry feces and carcasses in Ouagadougou, Burkina Faso

The importance of Salmonella and Campylobacter as foodborne pathogens is well recognized worldwide. Poultry and poultry products are commonly considered as the major vehicles of Salmonella and Campylobacter infection in humans. The aim of this study was to investigate the hygienic status of poultry facilities and determine the prevalence of Salmonella and Campylobacter in slaughtered poultry feces and carcasses in four different markets in Ouagadougou, capital city of Burkina Faso. A total of 103 poultry feces and 20 carcasses were analyzed using microbiological standard methods. Among the 103 fecal samples, 70 were positive for Campylobacter ssp (67.96%) and 54 for Salmonella ssp (52.42%). The hippurate hydrolysis test revealed that among the 70 Campylobacter strains isolated from feces, 49 were C. jejuni (70%) and 21 were C. coli (30%). From the 20 carcasses analyzed, 18 were contaminated with Salmonella (90%) and 10 with Campylobacter ssp (50%). Among the 10 Campylobacter ssp samples isolated from poultry carcasses, all were identified as C. jejuni using the API CAMPY system and the hippurate hydrolysis test. The assessment of markets hygienic practices for production, transportation, display, and vending of meat revealed unhygienic conditions. To complete the observation of unhygienic practices, we have sampled chicken-washing solution from the study sites and microbiological analysis of these samples revealed the presence of Salmonella spp in 100% of the samples. This study highlighted that poultry products on sale in Ouagadougou are highly contaminated with Salmonella and Campylobacter. To the best of our knowledge, this is the first report describing Campylobacter presence in the poultry industry of Burkina Faso. Our findings might help to better understand the epidemiology of Salmonella and Campylobacter.

A Rapid LAMP-Based Method for Screening Poultry Samples for Campylobacter Without Enrichment

Campylobacter is the most prominent bacterium associated with foodborne disease and the majority of human infection cases are attributed to chicken. Rapid methods capable of determining the Campylobacter status of poultry products in a short time are needed in today's fast-paced food supply chain. In this study, we developed and evaluated an easy to perform, rapid and robust method for direct detection of Campylobacter in poultry carcasses based on loop-mediated isothermal DNA AMPlification (LAMP). The method does not require bacterial culture or DNA purification and generates results in just an hour. A total of 171 swabs from chicken and turkey slaughter houses were analyzed in parallel by both LAMP and conventional culture-based enumeration methods to evaluate the performance of the rapid method. Campylobacter was detected by LAMP in 100% of swabs with an enumeration result of ≥800 cfu/swab, and 98.6% (69 out of 70) of samples reported as negative by enumeration (≤10 cfu/swab) were also negative by LAMP. The method is also suitable for analysis of boot swabs from poultry houses, and therefore it represents a convenient screening tool that can be implemented on farm, at slaughter houses, processing plants or retail, to help with the control of Campylobacter contamination throughout the food supply chain. The inclusion of an internal amplification control prevents any potential false negative results due to DNA amplification inhibitors that might be present in the sample.

Antimicrobial Resistance and Genotypes of Campylobacter jejuni from Pig and Cattle Carcasses Isolated in Poland During 2009-2016

Between 2009 and 2016, 317 and 529 swabs from cattle and pig carcasses, respectively, were collected all over Poland and tested for the presence of Campylobacter. Among 37 (11.7%) and 161 (30.4%) positive samples, 44 Campylobacter jejuni isolates were detected. A total of 29 different sequence types (STs) and 12 various clonal complexes were identified. Antimicrobial resistance revealed that 17 (38.6%) C. jejuni (10 from cattle and 7 from pig carcasses, respectively) were susceptible to all antimicrobials used in the study, whereas the remaining 27 (61.4%) isolates (12 from cattle and 15 from pigs, respectively) were resistant to at least one antimicrobial agent, mainly to quinolones (23 out of 44 isolates; 52.3%) and tetracyclines (14 strains; 31.8%). Only one isolate from cattle and two from pigs displayed resistance to streptomycin, and none of C. jejuni tested was resistant to erythromycin and gentamicin. All isolates with STs, ST356, ST443, ST464, ST658, ST2036, and ST6411, as well as some isolates belonging to ST257 and ST1947, were resistant to quinolones and tetracyclines. The results show that cattle and pigs may be a reservoir of quinolone and tetracycline resistant C. jejuni with STs which were previously isolated from humans with campylobacteriosis.

An illustrated key to and diagnoses of the species of Histeridae (Coleoptera) associated with decaying carcasses in Argentina

A key to 16 histerid species associated with decaying carcasses in Argentina is presented, including diagnoses and habitus photographs for these species. This article provides a table of all species associated with carcasses, detailing the substrate from which they were collected and geographical distribution by province. All 16 Histeridae species registered are grouped into three subfamilies: Saprininae (twelve species of Euspilotus Lewis and one species of Xerosaprinus Wenzel), Histerinae (one species of Hololepta Paykull and one species of Phelister Marseul) and Dendrophilinae (one species of Carcinops Marseul). Two species are new records for Argentina: Phelister rufinotus Marseuland Carcinops troglodytes (Paykull). A discussion is presented on the potential forensic importance of some species collected on human and pig carcasses.

Use of Petrifilm™ 3M to Assess Coliform Numbers on Lamb Carcasses

Petrifilm^™ (6410) was used directly on lamb carcasses to enumerate coliforms. Ten sampling locations (sites) on 30 carcasses were sampled at each of four separate meat processing establishments (works). The coliform counts obtained by this technique were statistically analyzed using analysis of variance (ANOVA) to select the optimum sampling sites on the carcass and to assess the contamination of the carcass by gut flora at a particular establishment. There was a large variation between sites and between works. In general, works 3 and 4 produced cleaner carcasses than works 2, which in turn was cleaner than works 1. Since works 1, 2 and 4 used conventional dressing techniques and works 3 used the inverted dressing method, the coliform counts found at works 3 and 4 are achievable regardless of dressing technique. The coliform bacteria were most concentrated around the posterior pelvic rim and least prevalent at the carcass extremities. The posterior pelvic rim (sites 3 and 4) had higher (P<0.05) coliform counts than the exterior ventral flank area (sites 5, 6, 7 and 8), which in turn had higher (P<0.05) counts than the proximal hind and proximal fore limbs (sites 1, 2, 9 and 10) across all works. With in-line routine testing it is recommended that the majority of carcasses sampled should give coliform counts of less than 50 colony forming units (CFU)/20 cm² for sites 4 and 8.