Investigation of risk factors for introduction of highly pathogenic avian influenza H5N1 virus onto table egg farms in the United States, 2022: a case-control study.

Introduction: The 2022-2023 highly pathogenic avian influenza (HPAI) H5N1 outbreak in the United States (U.S.) is the most geographically extensive and costly animal health event in U.S. history. In 2022 alone, over 57 million commercial and backyard poultry in 47 U.S. states were affected. Over 75% of affected poultry were part of the commercial table egg production sector. Methods: We conducted a case-control study to identify potential risk factors for introduction of HPAI virus onto commercial table egg operations. Univariate and multivariable analyses were conducted to compare farm characteristics, management, and biosecurity factors on case and control farms. Results: Factors associated with increased risk of infection included being in an existing control zone, sightings of wild waterfowl, mowing or bush hogging vegetation less than 4 times a month, having an off-site method of daily mortality disposal (off-site composting or burial, rendering, or landfill), and wild bird access to feed/feed ingredients at least some of the time. Protective factors included a high level of vehicle washing for trucks and trailers entering the farm (a composite variable that included having a permanent wash station), having designated personnel assigned to specific barns, having a farm entrance gate, and requiring a change of clothing for workers entering poultry barns. Discussion: Study results improve our understanding of risk factors for HPAI infection and control measures for preventing HPAI on commercial U.S. table egg farms.

Static Aerated Composting of African Swine Fever Virus-Infected Swine Carcasses with Rice Hulls and Sawdust.

Identifying and ensuring the inactivation of the African Swine Fever virus in deadstock is a gap in the swine industry's knowledge and response capabilities. The results of our study demonstrate that ASFv in deadstock was inactivated using static aerated composting as the carcass disposal method. Replicated compost piles with whole market hogs and two different carbon sources were constructed. In-situ bags containing ASFv-infected spleen tissue were placed alongside each of the carcasses and throughout the pile. The bags were extracted at days 0, 1, 3, 7, 14, 28, 56, and 144 for ASFv detection and isolation. Real-time PCR results showed that DNA of ASFv was detected in all samples tested on day 28. The virus concentration identified through virus isolation was found to be below the detection limit by day 3 in rice hulls and by day 7 in sawdust. Given the slope of the decay, near-zero concentration with 99.9% confidence occurred at 5.0 days in rice hulls and at 6.4 days in sawdust. Additionally, the result of virus isolation also showed that the virus in bone marrow samples collected at 28 days was inactivated.

Viability of African Swine Fever Virus with the Shallow Burial with Carbon Carcass Disposal Method.

African swine fever (ASF) is a highly contagious swine disease with high mortality. In many countries, culling pigs infected and exposed to the ASF virus is mandatory to control the disease, which poses a real challenge in the disposal of large numbers of carcasses during ASF outbreaks. Shallow burial with carbon (SBC) Thanks ew mortality disposal method developed from deep burial and composting. The present study investigates the effectiveness of SBC in disposing of ASF virus-infected pigs. The real-time PCR results showed that DNA of the ASF virus was still detected in bone marrow samples on day 56, while the virus isolation test revealed that the infectious ASF virus was destroyed in both spleen and bone marrow samples on day 5. Interestingly, decomposition was found to occur rapidly in these shallow burial pits. On day 144, only large bones were found in the burial pit. In general, the results of this study indicated that SBC is a potential method for the disposal of ASF-infected carcasses; however, further studies are needed to provide more scientific evidence for the efficacy of SBC in different environment conditions.

Manure management strategies are interconnected with complexity across U.S. dairy farms.

Among one of the key challenges in dairy production is the management of manure in a way that is beneficial for agricultural production, with minimal environmental and public health impacts. Manure management systems (MMS)-the entire system of handling, storage, and application of manure-are diverse in countries with developed dairy industries such as the United States, enabled by a number of different technologies. The ways in which dairy farmers manage manure is driven by varying tradeoffs, including economic, social, and environmental; however, existing research has not examined the relationships between components of MMS. Here we use data from the National Animal Health Monitoring System's Dairy 2014 study to explore the ways in which manure handling, storage, and application are related, using a series of logistic regression models and network associations. We found significant associations between how manure is handled, stored, and applied, especially driven by the consistency of manure. For solid manure, we found highly heterogeneous systems, where farmers may have a suite of alternative manure management strategies available to them, and substitution is viable. Conversely, farms using liquid manure systems have very few substitutes in their MMS, suggesting greater investment in certain infrastructures, which are not easily changed. Such findings have important implications for shifting farmers towards management practices with minimal environmental and public health impacts, demonstrating that not all farm systems are easily changed. We highlight these results in light of current policies, which may not fully capture the relationships across the MMS, and suggest that greater financing may be necessary to shift MMS on some farms. Furthermore, we suggest that different MMS have varying tradeoffs across environmental, social, and economic aspects, which demonstrates that MMS are highly individualized to a given farm's goals and priorities.

Virus viability in spiked swine bone marrow tissue during above-ground burial method and under in vitro conditions.

The emergence of high consequence animal diseases usually requires managing significant mortality. A desirable aspect of any carcass management method is the ability to contain and inactivate the target pathogen. The above-ground burial (AGB) technique was recently developed and proposed as an alternative carcass management method. Here, we investigate the tenacity of swinepox virus (SwPV), as a surrogate model for African swine fever virus (ASFV) in swine carcasses during the AGB process. For this, SwPV was inoculated intrafemorally in 90 adult swine carcasses, which were subsequently disposed under AGB conditions. Bone marrow samples were recovered periodically throughout 12 months and virus viability was assessed by virus isolation (VI), whereas the presence of SwPV DNA was evaluated by quantitative polymerase chain reaction (qPCR). Additionally, an in vitro study assessed the inactivation rate of SwPV, Senecavirus A (SVA), and bovine viral diarrhoea virus (BVDV). Viral suspensions were mixed with bone marrow material and maintained at 21-23°C for 30 days. Virus viability was assessed by VI and viral titration. In the field study, SwPV remained viable only in 11 (55%) bone marrow samples collected on day 7; only viral DNA (and not infectivity) was detected afterwards. SwPV inactivation was estimated to have occurred by day 11. The in vitro testing revealed a variable tenacity of the studied viruses. The viability period was estimated in 28, 80, and 118 days, respectively, for BVDV, SwPV, and SVA. Overall, these findings indicate that the AGB technique was effective in quickly inactivating SwPV. Additionally, the SwPV inactivation rate is comparable to ASFV under field studies and poses a potential model for preliminary ASFV inactivation studies with reduced biosecurity requirements. Moreover, this study contributes to understanding the inactivation kinetics of viruses under specific conditions, which is critical when designing and applying countermeasures in case of biosecurity breaches in sites managing animal mortality.