Survival of Escherichia coli in Airborne and Settled Poultry Litter Particles

Biosecurity Implications, Transmission Routes and Modes of Economically Important Diseases in Domestic Fowl and Turkey

The poultry industry is a critical source of affordable protein worldwide; however, it faces continuous threats from various poultry diseases that significantly impact public health, economic stability, and food security. Knowledge of and examination of the transmission routes, risk factors, and environmental survival characteristics of the most important pathogens affecting poultry populations, as well as the importance of strict biosecurity, are pivotal. Transmission routes are split into direct and vector-borne pathways, and indirect ways, which include infections via contaminated surfaces and vector-borne pathways, including insects and rodents. Avian influenza virus and Newcastle disease virus spread through respiratory droplets, and their transmission risk increases with increasing stocking density. While other pathogens (e.g., infectious bursal disease virus and Salmonella spp.), to persist long-term in the environments, for example, feed and litter, increasing the probability to persist long-term in the environments, for example, feed and litter, increasing the probability of infection. The long-term resilience of pathogens in multiple pathogens in various environmental conditions highlights the role of biosecurity, sanitation, and hygiene controls in preventing disease outbreaks. High stocking density in production systems, suboptimal ventilation, and inadequate biosecurity controls further increase transmission risks. This paper summarizes important disease transmissions and reinforces the need for strict biosecurity protocols and routine health monitoring to prevent the spread of pathogens within and beyond poultry facilities. These strategies can support safe poultry production, address growing global demand, and ensure food safety and public health.

Spatial analysis of airborne bacterial concentrations and microbial communities in a large-scale commercial layer facility

This study investigated the spatial distribution patterns of airborne bacterial concentrations and microbial community structures in a modern commercial layer facility housing approximately 50,000 laying hens equipped with advanced environmental control systems. Air samples were systematically collected at 50 strategically distributed locations using a six-stage Andersen microbial air sampler, while environmental samples (dust, manure, intestinal contents) were characterized using 16S rRNA gene sequencing. Results demonstrated a distinct longitudinal gradient in airborne bacterial concentrations, progressively increasing from the air inlet (883±177 CFU/m³) to exhaust fans (12,650±813 CFU/m³), with a facility-wide mean concentration of 5,618±530 CFU/m³. Spatial analysis revealed significant bacterial concentration heterogeneity, with elevated bacterial loads (>8,000 CFU/m³) concentrated in central regions while peripheral areas maintained lower concentrations (<6,000 CFU/m³). Taxonomic profiling identified Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes as predominant phyla across all sample types, with significant compartment-specific distribution patterns: Firmicutes dominated intestinal samples (72.9 %), Proteobacteria and Bacteroidetes were enriched in posterior dust and manure samples, while Acinetobacter exhibited highest abundance (19.90 %) in anterior dust. Differential abundance analysis demonstrated significant enrichment of fecal-associated bacteria (particularly Bacteroides and Escherichia coli) in posterior sampling locations, establishing direct correlations between environmental parameters and microbial dissemination patterns. This comprehensive spatial-microbial analysis elucidates critical factors influencing bacterial dispersion within intensive poultry production environments, providing the empirical foundation for implementing concentration-based risk stratification management systems and targeted interventions to enhance biosecurity, minimize disease transmission, and optimize poultry health in commercial operations.

Capacitive Biosensor for Rapid Detection of Avian (H5N1) Influenza and E. coli in Aerosols

Airborne transmission via aerosols is a dominant route for the transmission of respiratory pathogens, including avian H5N1 influenza A virus and E. coli bacteria. Rapid and direct detection of respiratory pathogen aerosols has been a long-standing technical challenge. Herein, we develop a novel label-free capacitive biosensor using an interlocked Prussian blue (PB)/graphene oxide (GO) network on a screen-printed carbon electrode (SPCE) for direct detection of avian H5N1 and E. coli. A single-step electro-co-deposition process grows GO branches on the SPCE surface, while the PB nanocrystals simultaneously decorate around the GO branches, resulting in an ultrasensitive capacitive response at nanofarad levels. We tested the biosensor for H5N1 concentrations from 2.0 viral RNA copies/mL to 1.6 × 105 viral RNA copies/mL, with a limit of detection (LoD) of 56 viral RNA copies/mL. We tested it on E. coli for concentrations ranging from 2.0 bacterial cells/mL to 1.8 × 104 bacterial cells/mL, with a LoD of 5 bacterial cells/mL. The detection times for both pathogens were under 5 min. When integrated with a custom-built wet cyclone bioaerosol sampler, our biosensor could detect and quasi-quantitatively estimate H5N1 and E. coli concentrations in air with spatial resolutions of 93 viral RNA copies/m3 and 8 bacterial cells/m3, respectively. The quasi-quantification method, based on dilution and binary detection (positive/negative), achieved an overall accuracy of >90% for pathogen-laden aerosol samples. This biosensor is adaptable for multiplexed detection of other respiratory pathogens, making it a versatile tool for real-time airborne pathogen monitoring and risk assessment.

Associations between acquired antimicrobial resistance genes in the upper respiratory tract and livestock farm exposures: a case-control study in COPD and non-COPD individuals

BACKGROUND

Livestock-related emissions have been associated with aggravations of respiratory symptoms in patients with chronic obstructive pulmonary disease (COPD), potentially by altering the respiratory resistome.

OBJECTIVES

This study investigates the structure of the acquired oropharyngeal (OP) resistome of patients with COPD and controls, its interplay with the respiratory microbiome and associations with residential livestock exposure.

METHODS

In a matched case-control study in the rural Netherlands, we analysed OP swabs from 35 patients with COPD and 34 controls, none of whom had used antibiotics in the preceding 4 weeks. Resistome profiling was performed using ResCap, complemented by prior characterization of the microbiome via 16S rRNA-based sequencing. Residential livestock farm exposure was defined using distance-based variables alongside modelled concentrations of livestock-emitted microbial pollutants. We compared resistome profiles between patients with COPD and controls, examining alpha and beta diversity as well as differential abundance. Additionally, we assessed the interplay between the resistome and microbiome using co-occurrence networks and Procrustes analysis. Variations in resistome profiles were also analysed based on residential livestock exposures.

RESULTS

Patients with COPD exhibited higher resistome diversity than controls (Shannon diversity, P = 0.047), though resistome composition remained similar between groups (PERMANOVA, P = 0.19). Significant correlations were observed between the OP resistome and microbiome compositions, with distinct patterns in co-occurrence networks. Residential exposure to livestock farms was not associated with resistome alterations.

CONCLUSIONS

Our findings reveal the COPD airway as a hospitable environment for antimicrobial resistance genes, irrespective of recent antimicrobial usage. Demonstrating the interplay between the resistome and microbiome, our study underscores the importance of a deeper understanding of the resistome in respiratory health.

Avian pathogenic Escherichia coli: Epidemiology, virulence and pathogenesis, diagnosis, pathophysiology, transmission, vaccination, and control

Avian pathogenic Escherichia coli (APEC) causes colibacillosis in poultry; this type of bacteria is an extraintestinal pathogen E. coli. Unlike other E. coli pathogen groups, the characteristics of APECs cannot be identified by a single group. Serotyping and biotyping are frequently performed for isolates found in colibacillosis infections. The establishment, transmission, and persistence of this pathogenic strain in chicken populations are determined by the intricate interactions of multiple elements that make up the epidemiology of APEC. APEC employs many virulence and pathogenesis factors or mechanisms to infect chickens with colibacillosis. These factors include invasives, protectins, adhesins, iron acquisition, and toxins. In addition, the pathogenicity of APEC strains can be evaluated in 2-4 week-old chicks. The impact of unfavorable environmental conditions has also been documented, despite direct contact being demonstrated to be a significant element in transmission in APEC. Chickens are immunized against colibacillosis using a variety of vaccines. Nevertheless, commercially available vaccinations do not offer sufficient immunity to protect birds from APEC strains. Hatching egg contamination is one of the main ways that APECs spread throughout chicken flocks. Farmers also need to be mindful of storing discarded materials near the manure-watering area, removing them when necessary, and replacing wet materials with dry materials when needed. This review aimed to explain the characteristics, epidemiology, virulence, pathogenesis, diagnosis, pathophysiology, transmission, vaccination, and control of APEC.

Comparison of Three Air Sampling Methods for the Quantification of Salmonella, Shiga-toxigenic Escherichia coli (STEC), Coliforms, and Generic E. coli from Bioaerosols of Cattle and Poultry Farms

Recent fresh produce outbreaks potentially associated with bioaerosol contamination from animal operations in adjacent land highlighted the need for further study to better understand the associated risk. The purpose of this research was to evaluate three sampling methods for quantifying target bacterial bioaerosols from animal operations. A dairy cattle and poultry farm located in Georgia, U.S. were visited six times each. Air was collected for 10 min using: 2-stage Andersen impactor with and without mineral oil overlay and impingement samplers. Sampling devices were run concurrently at 0.1, 1, and 2 m heights (n = 36). Andersen samplers were loaded with CHROMagar™ Salmonella, CHROMagar™ STEC, or Brilliance™ coliforms/E. coli. The impingement sampler contained buffered peptone water (20 mL) which was vacuum filtered through a 0.45 µm filter and placed onto the respective media. Plates were incubated at 37 ℃ for 48 h. PCR confirmation followed targeting ttr for Salmonella and stx1, stx2, and eae genes for STEC. No significant differences were found among methods to quantify coliforms and E. coli. Salmonella and STEC bioaerosols were not detected by any of the methods (Limit of detection: 0.55 log CFU/m3). E. coli bioaerosols were significantly greater in the poultry (2.76-5.00 log CFU/m3) than in the cattle farm (0.55-2.82 log CFU/m3) (p < 0.05), and similarly distributed at both stages in the Andersen sampler (stage 1:>7 μm; stage 2: 0.65-7 μm particle size). Sampling day did not have a significant effect on the recovery of coliforms/E. coli bioaerosols in the poultry farm when samples were taken at the broiler house exhaust fan (p > 0.05). A greater and constant emission of coliforms and E. coli bioaerosols from the poultry farm warrants further investigation. These data will help inform bioaerosol sampling techniques which can be used for the quantification of bacterial foodborne pathogens and indicator organisms for future research.

Distribution characteristics and potential risks of bioaerosols during scattered farming

In most economically underdeveloped areas, scattered farming and human‒livestock cohabitation are common. However, production of bioaerosols and their potential harm in these areas have not been previously researched. In this study, bioaerosol characteristics were analyzed in scattered farming areas in rural Northwest China. The highest bacteria, fungi, and Enterobacteria concentrations were 125609 ± 467 CFU/m³, 25175 ± 10305 CFU/m³, and 4167 ± 592 CFU/m³, respectively. Most bioaerosols had particle sizes >3.3 μm. A total of 71 bacterial genera and 16 fungal genera of potential pathogens were identified, including zoonotic potential pathogenic genera. Moreover, our findings showed that the scattered farming pattern of human‒animal cohabitation can affect the indoor air environment in the surrounding area, leading to chronic respiratory diseases in the occupants. Therefore, relevant government departments and farmers should enhance their awareness of bioaerosol risks and consider measures that may be taken to reduce them.

Modeling long-distance airborne transmission of highly pathogenic avian influenza carried by dust particles

Highly pathogenic avian influenza (HPAI) is continuously causing significant economic losses with massive poultry depopulations. Airborne transmission of HPAI was suspected, as initial bird mortalities were reported near air inlets of poultry houses. In addition, infected farms were distant, indicating that the viruses carried by dust particles might help the viruses travel for long distances in the environment. The objective of this study focused on simulating the airborne transmission of HPAI by using computational modeling to assess the risk of airborne and deposited avian influenza (AI) carried by poultry-litter dust particles. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) modeling was used in this study. Data from 168 infected cases in the Mid-Western area of U.S. were obtained from the Animal and Plant Health Inspection Service (APHIS) and Watt Poultry. The concentration simulation modeling was performed to estimate the airborne and deposited AI concentration carried by PM2.5 dust particles. Results showed that concentrations of airborne AI, deposited AI, and combined AI transmitted to other farms in a day were lower than the minimal infective dose for poultry. In most of the scenarios, the predicted probability of infection showed that Iowa-infected farms and turkey poultry houses had the highest infection probability. The findings may provide an understanding of the risk of airborne HPAI virus carried by dust particles and suggest the factors that influence long-distance airborne transmission.

Investigations of Histomonosis-Favouring Conditions: A Hypotheses-Generating Case-Series-Study

Since the ban of effective feed additives and therapeutics, histomonosis has become an important disease and, subsequently, a welfare issue for turkey production. We conducted an interview-based case series study to generate hypotheses about possible disease-favouring conditions in 31 H. meleagridis-infected flocks. The determined parameters were related to the general farm (flock management, biosecurity measures, etc.) as well as the histomonosis-specific disease management. Some inadequate biosecurity measures were observed. An inappropriate usage of the hygiene lock and cleaning as well as the disinfection frequency of equipment, clothes, and the hygiene lock could possibly be histomonosis-favouring conditions. These factors could increase the risk for the introduction of H. meleagridis and the risk of a pathogen spread on an affected farm. Insects, wild birds, litter materials, and contaminated dung could be potential vectors of H. meleagridis. Predisposing gastrointestinal diseases were observed in 71% of the affected flocks. Additionally, stress events related to higher temperature, movement of birds, and vaccination were documented in association with clinical histomonosis. The results emphasise the need for both good disease control and health management to ensure sustainable animal health and welfare.

Research progress of severe acute respiratory syndrome coronavirus 2 on aerosol collection and detection

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in late 2019 has negatively affected people's lives and productivity. Because the mode of transmission of SARS-CoV-2 is of great concern, this review discusses the sources of virus aerosols and possible transmission routes. First, we discuss virus aerosol collection methods, including natural sedimentation, solid impact, liquid impact, centrifugal, cyclone and electrostatic adsorption methods. Then, we review common virus aerosol detection methods, including virus culture, metabolic detection, nucleic acid-based detection and immunology-based detection methods. Finally, possible solutions for the detection of SARS-CoV-2 aerosols are introduced. Point-of-care testing has long been a focus of attention. In the near future, the development of an instrument that integrates sampling and output results will enable the real-time, automatic monitoring of patients.

Bacterial and viral rodent-borne infections on poultry farms. An attempt at a systematic review

Introduction

Rodents are quite common at livestock production sites. Their adaptability, high reproductive capacity and omnivorousness make them apt to become a source of disease transmission to humans and animals. Rodents can serve as mechanical vectors or active shedders of many bacteria and viruses, and their transmission can occur through direct contact, or indirectly through contaminated food and water or by the arthropods which parasitise infected rodents. This review paper summarises how rodents spread infectious diseases in poultry production.

Material and Methods

The aim of this review was to use PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) principles to meta-analyse the available data on this topic. Three databases – PubMed, Web of Science and Scopus – and grey literature were searched for papers published from inception to July 2022 using the established keywords.

Results

An initial search identified 2,999 articles that met the criteria established by the keywords. This number remained after removing 597 articles that were repeated in some databases. The articles were searched for any mention of specific bacterial and viral pathogens.

Conclusion

The importance of rodents in the spread of bacterial diseases in poultry has been established, and the vast majority of such diseases involved Salmonella, Campylobacter, Escherichia coli, Staphylococcus (MRSA), Pasteurella, Erysipelothrix or Yersinia infections. Rodents also play a role in the transmission of viruses such as avian influenza virus, avian paramyxovirus 1, avian gammacoronavirus or infectious bursal disease virus, but knowledge of these pathogens is very limited and requires further research to expand it.

Effect of Ultraviolet Radiation on Reducing Airborne Escherichia coli Carried by Poultry Litter Particles

Airborne Escherichia coli (E. coli) originating in poultry houses can be transmitted outside poultry farms through the air, posing risks of barn-to-barn infection through airborne transmission. The objective of this study is to examine the effect of ultraviolet (UV) light on the inactivation of airborne E. coli carried by poultry dust particles under laboratory conditions. A system containing two chambers that were connected by a UV scrubber was designed in the study. In the upstream chamber of the system, airborne E. coli attached to dust particles were aerosolized by a dry aerosolization-based system. Two sets of air samplers were placed in the two chambers to collect the viable airborne E. coli. By comparing the concentration of airborne E. coli in the two chambers, the inactivation rates were calculated. The airborne E. coli inactivation rates were tested at different contact times with the aid of a vacuum pump (from 5.62 to 0.23 s of contact time) and different UV irradiance levels (of 1707 µW cm^-2 and 3422 µW cm^-2). The inactivation rates varied from over 99.87% and 99.95% at 5.62 s of contact time with 1707 µW cm^-2 and 3422 µW cm^-2 of UV irradiance to 72.90% and 86.60% at 0.23 s of contact time with 1707 µW cm^-2 and 3422 µW cm^-2 of UV irradiance. The designed system was able to create the average UV irradiation of 1707 µW cm^-2 and 3422 µW cm^-2 for one UV lamp and two UV lamps, respectively. The findings of this study may provide an understanding of the effect of UV light on the inactivation of airborne E. coli carried by dust particles and help to design an affordable mitigation system for poultry houses.

Transmission of antimicrobial resistance (AMR) during animal transport

The transmission of antimicrobial resistance (AMR) between food-producing animals (poultry, cattle and pigs) during short journeys (< 8 h) and long journeys (> 8 h) directed to other farms or to the slaughterhouse lairage (directly or with intermediate stops at assembly centres or control posts, mainly transported by road) was assessed. Among the identified risk factors contributing to the probability of transmission of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs), the ones considered more important are the resistance status (presence of ARB/ARGs) of the animals pre-transport, increased faecal shedding, hygiene of the areas and vehicles, exposure to other animals carrying and/or shedding ARB/ARGs (especially between animals of different AMR loads and/or ARB/ARG types), exposure to contaminated lairage areas and duration of transport. There are nevertheless no data whereby differences between journeys shorter or longer than 8 h can be assessed. Strategies that would reduce the probability of AMR transmission, for all animal categories include minimising the duration of transport, proper cleaning and disinfection, appropriate transport planning, organising the transport in relation to AMR criteria (transport logistics), improving animal health and welfare and/or biosecurity immediately prior to and during transport, ensuring the thermal comfort of the animals and animal segregation. Most of the aforementioned measures have similar validity if applied at lairage, assembly centres and control posts. Data gaps relating to the risk factors and the effectiveness of mitigation measures have been identified, with consequent research needs in both the short and longer term listed. Quantification of the impact of animal transportation compared to the contribution of other stages of the food-production chain, and the interplay of duration with all risk factors on the transmission of ARB/ARGs during transport and journey breaks, were identified as urgent research needs.

Nebulization as a more efficient method than atomizer for experimental reproduction of avian colibacillosis in young chickens

ABSTRACTInfection and immunity studies involving genetically modified organisms (GMOs), such as gene knockout bacterial mutants require stringent physical containment to prevent the accidental spread of these organisms into the environment. Experimental respiratory tract infection models often require the animals, for example birds, to be transported several times between a negative pressure housing isolator and a bespoke aerosol exposure chamber under positive pressure. While the exposure chamber is sealed and fitted with HEPA filters, the repeated movements of infected animals and opening of the chamber can still pose a serious risk of breaching containment of the organism in the experimental facility. In the current study, the ability of two aerosol infection protocols that expose birds to avian pathogenic E. coli (APEC) aerosols directly within the housing isolator was evaluated. Young chicks were exposed to APEC E956 within the negative pressure housing isolators using either a nebulizer or an atomizer. Birds exposed twice (days 1 and 4) to aerosols of APEC E956 produced by the nebulizer developed a rapidly progressing disease mimicking field cases of avian colibacillosis. However, birds exposed to aerosols of APEC E956 produced by an atomizer, did not develop colibacillosis even after 3 exposures to APEC E956 on days 1, 4 and 7. Consequently, the current study reports the nebulizer was more efficacious in producing avian colibacillosis under stricter bacterial containment settings.