Detection of spatial and temporal spread of Mycobacterium avium subsp. paratuberculosis in the environment of a cattle farm through bio-aerosols

Proteomic profiling of membrane vesicles from Mycobacterium avium subsp. paratuberculosis: Navigating towards an insilico design of a multi-epitope vaccine targeting membrane vesicle proteins

Bacteria typically produce membrane vesicles (MVs) at varying levels depending on the surrounding environments. Gram-negative bacterial outer membrane vesicles (OMVs) have been extensively studied for over 30 years, but MVs from Gram-positive bacteria only recently have been a focus of research. In the present study, we isolated MVs from Mycobacterium avium subsp. paratuberculosis (MAP) and analyzed their protein composition using LC-MS/MS. A total of 316 overlapping proteins from two independent preparations were identified in our study, and topology prediction showed these cargo proteins have different subcellular localization patterns. When MVs were administered to bovine-derived macrophages, significant up-regulation of pro-inflammatory cytokines was observed via qRT-PCR. Proteome functional annotation revealed that many of these proteins are involved in the cellular protein metabolic process, tRNA aminoacylation, and ATP synthesis. Secretory proteins with high antigenicity and adhesion capability were mapped for B-cell and T-cell epitopes. Antigenic, Immunogenic and IFN-γ inducing B-cell, MHC-I, and MHC-II epitopes were stitched together through linkers to form multi-epitope vaccine (MEV) construct against MAP. Strong binding energy was observed during the docking of the 3D structure of the MEV with the bovine TLR2, suggesting that the putative MEV may be a promising vaccine candidate against MAP. However, in vitro and in vivo analysis is required to prove the immunogenic concept of the MEV which we will follow in our future studies. SIGNIFICANCE: Johne's disease is a chronic infection caused by Mycobacterium avium subsp. paratuberculosis that has a potential link to Crohn's disease in humans. The disease is characterized by persistent diarrhea and enteritis, resulting in significant economic losses due to reduced milk yield and premature culling of infected animals. The dairy industry in the United States alone experiences losses of approximately USD 250 million due to Johne's disease. The current vaccine against Johne's disease is limited by several factors, including variable efficacy, limited duration of protection, interference with diagnostic tests, inability to prevent infection, and logistical and cost-related challenges. Nevertheless, a multiepitope vaccine design approach targeting M. avium subsp. paratuberculosis has the potential to overcome these challenges and offer improved protection against Johne's disease.

Molecular Diversity of Mycobacterium avium subsp. paratuberculosis in Four Dairy Goat Herds from Thuringia (Germany)

This study investigated the intra- and inter-herd diversity of Mycobacterium avium subsp. paratuberculosis (MAP) isolates from four goat herds in Thuringia (Germany) that were affected by paratuberculosis for several years. The main focus was on the characterization and distribution of genotypes among animals and the environment of goat herd 1. This study included 196 isolates from the feces of 121 infected goats, various tissues from 13 clinically diseased goats, 29 environmental samples from herd 1, and additionally, 22 isolates of different origin from herds 2 to 4. The isolates, sampled between 2018 and 2022, were genotyped using short-sequence-repeat (SSR) analysis, mycobacterial-interspersed repetitive units-variable-number tandem repeat (MIRU-VNTR) analysis, and a single nucleotide polymorphism (SNP)-based assay for phylogenetic grouping. All the isolates belonged to the MAP-C group. In herd 1, one predominant genotype was determined, while two other genotypes were identified very rarely and only in fecal and environmental samples. One of three further genotypes was found in each of herds 2 to 4. The assignment of genotypes to different phylogenetic clades suggested six different infection strains. The results indicated no epidemiological links between the examined herds. Based on the current MAP genotyping data from Germany, possible sources of infection are MAP-contaminated barns previously used by infected cattle and the purchase of sub-clinically infected goats.

Utilisation of Actiphage in combination with IS900 qPCR as a diagnostic tool for rapid determination of paratuberculosis infection status in small ruminant herds

Introduction

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of paratuberculosis, a chronic infectious intestinal disease occurring in domestic and wild ruminants. Early diagnosis of infected herds enabling timely adoption of control measures is tremendously important in view of the fact that the disease has a significant economic impact on farmers. The aim of this study was to evaluate the possibility of rapid detection of viable MAP on small ruminant farms based on environmental sample examination using a novel phage-based test named Actiphage.

Material and Methods

A total of 9 fresh and 28 frozen (8 or 11 years at -70°C) environmental samples originating from paratuberculosis-affected farms were analysed for the presence of MAP by four different diagnostic methods: Actiphage combined with real-time PCR targeting insertion sequence 900 (IS900 qPCR), conventional phage amplification assay, culture (frozen samples only), and direct ĪS900 qPCR.

Results

Viable MAP was detected in one fresh environmental sample using Actiphage-IS900 qPCR. None of the frozen samples tested positive using this diagnostic approach, which was consistent with the results of culture examination also providing information on viability.

Conclusion

This study describes other possible and innovative uses of phage-based methods in paratuberculosis control strategies. The Actiphage-qPCR was found to be less laborious than culture and provided results within six hours, suggesting that it may be a valuable tool for rapid initial determination of the infectious status of farmed animals based on environmental sample examination.

Mycobacterium avium subsp. Paratuberculosis in Different Environmental Samples from a Dairy Goat Barn-Implications for Sampling Strategies for Paratuberculosis Diagnostic and Prevention

Environmental samples are often used to classify the paratuberculosis status of cattle herds. The disease is caused by Mycobacterium avium subsp. paratuberculosis (MAP), predominantly through oral ingestion during infancy. In this explorative study, the presence of MAP was determined in the barn environment of a paratuberculosis-infected vaccinated dairy goat herd. A total of 256 bedding, dust, feed, and water samples were collected at eight time points and examined using culture and qPCR. Detection rates of both methods were compared, and factors determining MAP confirmation were identified. MAP was cultured from 28 bedding and one dust sample, while MAP DNA was detected in all materials (117/256). Samples from high animal traffic areas and those collected during the indoor season were more likely to yield positive culture and qPCR results. Cultivation of MAP from kidding pens indicated this area as a possible infection site. Dust proved to be the most suitable material for detecting MAP DNA, as bedding was for MAP culture. Environmental sampling was demonstrated to be an effective way to detect MAP in a dairy goat herd. qPCR results could confirm herd infection, while culture results provided insight into crucial areas for MAP transmission. These findings should be considered when designing farm-specific paratuberculosis control plans.

Analysis of long non-coding RNA expression profile of bovine monocyte-macrophage infected by Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of paratuberculosis. As a potential zoonotic pathogen, MAP also seriously threatens human health and social security. At present, long non-coding RNA (lncRNA) has attracted wide attention as an useful biomarker in various diseases. Therefore, our study analyzed the lncRNA expression profiles and lncRNA-mRNA regulatory network of MAP infected bovine monocytes-macrophages and uninfected bovine cells by high-throughput sequencing. A total of 4641 differentially expressed lncRNAs genes were identified, including 3111 up-regulated genes and 1530 down-regulated genes. In addition, lncRNA-mRNA interaction analysis was performed to predict the target genes of lncRNA. Among them, after MAP infection, 86 lncRNAs targeted to mRNA, of which only 6 genes were significantly different. The results of Gene Ontology (GO) enrichment analysis showed that the differentially expressed genes significantly enriched in functional groups were related to immune regulation. Multiple signal pathways including NF-κB, NOD-like receptor, Cytokine-cytokine receptor, Toll-like receptor signaling pathway, Chemokine signaling pathway, and other important biochemical, metabolic and signal transduction pathways were enriched in Kyoto Encyclopedia of Genes and Genomes (KEGG). In this study, analysis of macrophage transcriptomes in response to MAP infection is expected to provide key information to deeply understand role of the pathogen in initiating an inappropriate and persistent infection in susceptible hosts and molecular mechanisms that might underlie the early phases of paratuberculosis.

Analysis of Colostrum and Udder Skin Swabs from a Dairy Goat Herd in Germany regarding the Occurrence of Mycobacterium avium Subsp. paratuberculosis

Simple Summary

The analysis of transmission routes for paratuberculosis as well as their prevention are critical for effective disease control. The aim of the present study was to assess the importance of colostrum and the udder skin as routes for transmission of Mycobacterium avium subspecies paratuberculosis (MAP) within a dairy goat herd. Swabs of the udder skin and colostrum samples were collected from goats of a paratuberculosis-infected herd during lambing season and analyzed for MAP DNA. Additionally, cultivation of the swabs was performed. MAP could not be detected in the colostrum. A low number of udder skin swabs was positive for MAP DNA but no bacteria could be cultured. Because the detection methods are imperfect, the occurrence of MAP in colostrum or on the udder skin can never be completely excluded. Therefore, present recommendations concerning colostrum and youngstock management should still be re-evaluated, but applied in goat herds within a paratuberculosis control program until the role of colostrum and udder skin for within-herd transmission of MAP is further investigated.

Abstract

Oral intake of Mycobacterium avium subspecies paratuberculosis (MAP) in first days of life is considered to be the main route of infection for paratuberculosis. This can be related to a direct contact to contaminated feces or feeding of MAP containing colostrum. Colostrum is believed to become contaminated either by lactogenic shedding or introduction of MAP from environmental sources. In this pilot study, the presence of MAP in individual and bulk colostrum samples from a paratuberculosis-infected, vaccinated dairy goat herd in Germany and the effect of udder skin disinfection on the MAP load of colostrum were examined. In order to distinguish between lactogenic shedding and fecal contamination, 49 udder skin swabs were cultivated on solid medium whereas 29 swabs were additionally analyzed by qPCR. qPCR was applied on 110 individual colostrum samples collected from 55 goats, one before and one after disinfection with a mycobactericidal disinfectant, and 14 bulk colostrum samples. MAP DNA was detected in 10.3% (3/29) of the swab samples, but no viable MAP was cultivated from any sample. These results indicate a low-level MAP contamination of the udder skin and colostrum of milking goats suggesting a low risk of MAP transmission via these routes.

Analysis of mRNA and circRNA Expression Profiles of Bovine Monocyte-Derived Macrophages Infected With Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subsp. paratuberculosis (MAP) is the pathogen of Johne’s disease (paratuberculosis), which mainly causes chronic infectious granulomatous enteritis in ruminants and has brought huge economic losses to animal husbandry. As a specific intracellular pathogen, when MAP invades the body, it is internalized by macrophages where it is able to replicate by inhibition of the phagosome maturation, escaping the host immune system and surviving, which leads to the spread of the disease. More recent studies have shown that circRNA is involved in many pathological and physiological processes of the body as the molecular sponge of miRNA, the scaffold of RNA binding protein and having the characteristic of being able to translate into protein. In this study, the mRNA and circRNA expression profiles of MAP-infected bovine monocyte-macrophages and uninfected bovine cells were analyzed by high-throughput sequencing. A total of 618 differentially expressed mRNA were screened out, including 322 upregulated mRNA and 296 downregulated mRNA. In addition, the analysis of circRNA differential expression profile showed 39 differentially expressed genes including 12 upregulated and 27 downregulated genes. Moreover, differential genes belonging to cytokine activity, chemokine activity, inflammatory reaction, apoptosis, and other functional groups related to macrophage immune response were significantly enriched in Gene Ontology (GO). Multiple signal pathways including NF-κB, MAPK, Toll-like receptor, IL-17, JAK-STAT, and other signaling pathways related to activating macrophage immune response were significantly enriched in Kyoto Encyclopedia of Genes and Genomes (KEGG). In addition, RT-qPCR technology verified the accuracy of the mRNA sequencing results. In this study, we have obtained the transcriptome information of mRNA and circRNA of bovine monocyte-macrophage infected with MAP. These results will provide data support for the further study of mRNA–miRNA–circRNA network and immune escape mechanism of MAP and will enrich the knowledge of the molecular immune mechanisms of Johne’s disease as well.

Johne's Disease in Dairy Cattle: An Immunogenetic Perspective

Johne's disease (JD), also known as paratuberculosis, is a severe production-limiting disease with significant economic and welfare implications for the global cattle industry. Caused by infection with Mycobacterium avium subspecies paratuberculosis (MAP), JD manifests as chronic enteritis in infected cattle. In addition to the economic losses and animal welfare issues associated with JD, MAP has attracted public health concerns with potential association with Crohn's disease, a human inflammatory bowel disease. The lack of effective treatment options, such as a vaccine, has hampered JD control resulting in its increasing global prevalence. The disease was first reported in 1895, but in recognition of its growing economic impact, extensive recent research facilitated by a revolution in technological approaches has led to significantly enhanced understanding of the immunological, genetic, and pathogen factors influencing disease pathogenesis. This knowledge has been derived from a variety of diverse models to elucidate host-pathogen interactions including in vivo and in vitro experimental infection models, studies measuring immune parameters in naturally-infected animals, and by studies conducted at the population level to enable the estimation of genetic parameters, and the identification of genetic markers and quantitative trait loci (QTL) putatively associated with susceptibility or resistance to JD. The main objectives of this review are to summarize these recent developments from an immunogenetics perspective and attempt to extract the principal and common findings emerging from this wealth of recent information. Based on these analyses, and in light of emerging technologies such as gene-editing, we conclude by discussing potential future avenues for effectively mitigating JD in cattle.

Dynamic of Mycobacterium avium subspecies paratuberculosis infection in a domestic-wildlife interface: Domestic sheep and guanaco as reservoir community

Natural herbivore populations have experienced uninterrupted pressures from direct and evident domestic-wildlife interactions and competition, to indirect or less obvious ones such as pathogen transmission. Thus, pathogen spillover between wild and domestic animals is a constant concern because the domestic-wildlife interface represents the ecological frontier in which pathogen transmission takes place in both directions. In Patagonian steppe communities, extensive sheep ranching and guanaco (Lama guanicoe) populations coexist, and guanaco have shown to be infected by pathogens such as Mycobacterium avium subspecies paratuberculosis (MAP) likely transmitted from livestock. MAP causes chronic enteritis and affects mostly domestic ruminants. We evaluated MAP prevalence and pathogen shedding in both species' faeces collected in non-shared and shared sites according to presence/absence of sheep and guanaco along a year, in four different seasons (autumn, winter, and spring 2018, and summer 2019). Our results indicate that MAP circulates in both sheep and guanaco populations with self-sustained transmission; however, both species differ in their levels of competence. We detected higher pathogen shedding in sites occupied by sheep, suggesting that sheep populations may be the main source of infection for susceptible animals due to their large numbers which drive MAP dynamics.

Pathology, immunohistochemistry and molecular study of cattle screened by comparative tuberculin test for diagnosis latent form of Johne's disease

Mycobacterium avium subsp. paratuberculosis causes Johne's disease in cattle and other ruminants. It is one of the most widespread in terms of prevalence and one of the most important diseases in the livestock industry in terms of economic importance. In the latent form of the disease, animals can act as carriers. The main purpose of this study was to evaluate avian tuberculin in a single intradermal comparative tuberculin test (SICTT), histopathology, immunohistochemistry, and molecular methods for diagnosis of infected cows with the latent form of the disease. Twenty-three asymptomatic cows and without post-mortem signs of the disease were selected using the single intradermal comparative tuberculin test and were tested. In this study, avian tuberculin in SICTT was able to in diagnosing the latent form of the disease. The results confirm immunohistochemistry and real-time PCR as a sensitive and reliable diagnostic complementary approach for detecting latent forms of Paratuberculosis.

Removal of bovine digital dermatitis-associated treponemes from hoof knives after foot-trimming: a disinfection field study

Background

Bovine digital dermatitis (BDD) is an infectious foot disease found commonly in dairy herds. Foot-trimming is an important husbandry procedure for reducing the ensuing lameness; however, epidemiological, and microbiological studies have identified this as a risk activity for transmitting BDD.

Three disinfectants have previously been identified in laboratory work as effective for removing viable BDD-associated Treponema spp., from hoof knife blades. The present study enrolled 133 dairy cattle with BDD lesions, and swabbed hoof knife blades before and after foot-trimming, and after knife disinfection with one of three disinfectants (1:100 FAM30®, 2% Virkon® and 2% sodium hypochlorite) to assess their efficacy under field conditions.

Results

Detection of BDD treponeme phylogroup DNA was undertaken by direct PCR of swabs, and viable treponemes were detected by PCR of swab cultures after 6 weeks’ incubation.

Where hoof knives did not contact the lesion, BDD-associated treponemes were detected after foot-trimming in 12/22 (54.5%) cases by direct PCR and 1/22 (4.5%) cases by PCR of cultured organisms. Where contact was made with the lesion, 111/111 (100%) samples taken after trimming were positive by direct PCR and 47/118 (39.8%) were positive by culture PCR. Viable organisms were identified in cultures from lesion stages M2, M3, M4 and M4.1. No viable organisms were detected after disinfection of hoof knives.

Conclusions

Hoof knives post-trimming were frequently contaminated with BDD-associated treponeme DNA. Viable organisms were identified in cultures whether contact had been made between hoof knife and lesion or not, although contact clearly increased the frequency of detection of viable organisms. The three disinfectants tested were effective for removing viable organisms. The disinfection protocol used in this study should therefore be considered reliable for adoption as standard industry practice.

A pilot study using environmental screening to determine the prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) and antimicrobial resistance (AMR) in Irish cattle herds

BACKGROUND

Dairy and beef cattle can be reservoirs of many pathogens, including Salmonella and Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of Johne's disease (JD). Farm environments may provide potential entry points for the transmission of infectious agents into the food chain. Antibiotics are used to treat a wide variety of infections on farms, and administration of antimicrobial agents to cattle is considered to be a driving factor for antimicrobial resistance (AMR). Control of JD and AMR are priority for animal health initiatives in Ireland. A national JD pilot programme was introduced by Animal Health Ireland in 2014, while the national action plan launched by Department of Health and Department of Agriculture, Food and Marine introduced in 2017 aims to improve the surveillance of AMR. The current investigation was undertaken as a pilot study to determine the proportion of herds positive for MAP, Salmonella species (Salmonella spp), commensal Escherichia coli (E. coli), Extended-spectrum beta-lactamase (ESBL) AmpC β-lactamase and carbapenemase-producing E. coli from 157 environmental faecal samples in Irish farms.

RESULTS

MAP was detected in 10.2% of samples collected; on culture in 4 (4.9%) of the dairy herds and from 1 (1.3%) of the beef/suckler herds, and by PCR in 10 (12.3%) and 6 (7.9%) of these herds respectively. All culture positive herds were also positive by PCR. An additional 11 herds were positive by PCR only. Salmonella was not detected, while commensal E. coli were isolated from 70.7% of the samples (111/157) with 101 of these isolates shown to be fully susceptible to all antimicrobials tested. Of the 27 presumptive ESBL AmpC β-lactamase producing E. coli detected, one isolate was resistant to ten antimicrobials, nine isolates were resistant to nine antimicrobials, and four isolates were resistant to eight antimicrobials. Carbapenemase-producing E. coli were not isolated.

CONCLUSIONS

The results highlight the importance of monitoring farm environments for Johne's disease. This disease is a growing concern for dairy and beef producers in Ireland, and sampling the farm environment may offer a useful means to rapidly screen for the presence of MAP. Non-pathogenic common enteric commensal and multiple-drug-resistant E. coli may contribute to AMR acting as a reservoir and transferring resistance to other species/pathogens in the environment.

Paratuberculosis in dairy goat flocks from southern Spain: risk factors associated with seroprevalence

BACKGROUND

Paratuberculosis (PTB) is a chronic, enteric wasting disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP), with a worldwide distribution. Andalusia, located in southern Spain, is one of the European regions with the highest goat census and the highest milk production; however, current data on the prevalence of MAP in this species are not available.

METHODS

A cross-sectional study was performed to determine the seroprevalence and risk factors associated with PTB in dairy goat flocks from southern Spain. A total of 3312 serum samples were collected from 48 flocks located in three different geographical areas. Health and productive parameters were surveyed during the visit to the herds.

RESULTS

A total of 511 goats were seropositive, with overall true seroprevalence of 22.54 per cent (95 per cent confidence interval (CI₉₅) 21.12-23.97). Of the goat herds, 87.50 per cent (CI₉₅78.14-96.98) were seropositive. The intraherd seroprevalence was 25.43±31.71, distributed as follows: 22 flocks with a seroprevalence under 10 per cent; 18 flocks between 10 per cent and 50 per cent; and eight flocks with a frequency over 50 per cent. Multivariate logistic regression showed significant association between PTB seropositivity and the following variables: intensive production system, lack of management by batches, inappropriate ventilation and seropositivity to c aprine a rthritis e ncephalitis v irus ( CAEV ).

CONCLUSIONS

The results indicate a widespread PTB infection in goat herds in southern Spain. Thus, control programmes must include management and sanitary measures to reduce the prevalence. Further experimental studies are necessary to determine the influence of CAEV-PTB coinfection on immune status.

Effects of Age and Environment on Adaptive Immune Responses to Mycobacterium avium subsp. paratuberculosis (MAP) Vaccination in Dairy Goats in Relation to Paratuberculosis Control Strategies

Paratuberculosis infection is caused by Mycobacterium avium subsp. paratuberculosis (MAP). In the Netherlands, 75% herd level prevalence of caprine paratuberculosis has been estimated, and vaccination is the principal control strategy applied. Most goat dairy farms with endemic paratuberculosis systematically vaccinate goat kids in the first months of life with a commercially available whole cell MAP vaccine. We hypothesized that the development of adaptive immune responses in goats vaccinated at young age depends on the environment they are raised in, and this has implications for the application of immune diagnostic tests in vaccinated dairy goats. We evaluated the early immune response to vaccination in young goat kids sourced from a MAP unsuspected non-vaccinated herd and raised in a MAP-free environment. Subsequently we compared these with responses observed in birth year and vaccination matched adult goats raised on farms with endemic paratuberculosis. Results indicated that initial adaptive immune responses to vaccination are limited in a MAP-free environment. In addition, adult antibody positive vaccinated goats raised in a MAP endemic environment are less likely to be IS900 PCR-positive as compared to antibody negative herd mates. We conclude that test-and-cull strategies in a vaccinated herd are currently not feasible using available immune diagnostic tests.

A review of paratuberculosis in dairy herds - Part 1: Epidemiology

Bovine paratuberculosis is a chronic infectious disease of cattle caused by Mycobacterium avium subspecies paratuberculosis (MAP). This is the first in a two-part review of the epidemiology and control of paratuberculosis in dairy herds. Paratuberculosis was originally described in 1895 and is now considered endemic among farmed cattle worldwide. MAP has been isolated from a wide range of non-ruminant wildlife as well as humans and non-human primates. In dairy herds, MAP is assumed to be introduced predominantly through the purchase of infected stock with additional factors modulating the risk of persistence or fade-out once an infected animal is introduced. Faecal shedding may vary widely between individuals and recent modelling work has shed some light on the role of super-shedding animals in the transmission of MAP within herds. Recent experimental work has revisited many of the assumptions around age susceptibility, faecal shedding in calves and calf-to-calf transmission. Further efforts to elucidate the relative contributions of different transmission routes to the dissemination of infection in endemic herds will aid in the prioritisation of efforts for control on farm.

HEALTH SURVEY OF BOREAL CARIBOU (RANGIFER TARANDUS CARIBOU) IN NORTHEASTERN BRITISH COLUMBIA, CANADA

Boreal woodland caribou (Rangifer tarandus caribou) are listed as threatened across Canada, and a basic understanding of their health status is lacking. From December 2012 to April 2013, we investigated multiple health indices for adult female boreal caribou (n=163) captured from seven herds in NE British Columbia, Canada. Health indices included physical characteristics, physiologic and trace mineral status, exposure to or infection with selected pathogens, and measures of chronic stress and inflammation, including serum amyloid A, haptoglobin, and hair cortisol concentration. Key findings were exposure to the bacterium Erysipelothrix rhusiopathiae in 14% of individuals, mild to severe hair loss associated with winter tick (Dermacentor albipictus) infestations in 76% of caribou from December to early February and 81% from late February to early April, and evidence of trace mineral deficiencies with 99% and 34% of individuals deficient in copper and selenium, respectively. Seroprevalence for exposure to selected pathogens was: alphaherpesvirus (63%), pestivirus (1%), Besnoitia spp. (60%), and Neospora caninum (2%). All animals were seronegative to Brucella spp. and Toxoplasma gondii. Mycobacterium avium ssp. paratuberculosis was not detected in any fecal samples. Parasite eggs or larvae, including Parelaphostrongylus andersoni (36%), Skrjabinema spp. (1%), Strongyle-type eggs (11%), Moniezia-type eggs (8%), and nematodirines (3%), were detected on fecal examination, but at low intensity. Blood biochemistry values and hair cortisol concentrations were within ranges previously reported in Rangifer tarandus sspp. Some significant differences among herds were noted, including antler morphology, exposure to Besnoitia spp., and concentrations of serum amyloid A, copper, cobalt, manganese, and iron.

Management of Coxiella burnetii infection in livestock populations and the associated zoonotic risk: A consensus statement

Infections caused by Coxiella burnetii, commonly referred to as coxiellosis when occurring in animals and Query fever when occurring in humans, are an important cause of abortions, decreased reproductive efficiency, and subclinical infections in ruminants. The organism also represents an important zoonotic concern associated with its ability to aerosolize easily and its low infectious dose. Available diagnostic tests have limited sensitivity, which combined with the absence of treatment options in animals and limited approaches to prevention, result in difficulty managing this agent for optimal animal health and zoonotic disease outcomes. The purpose of this consensus statement is to provide veterinarians and public health officials with a summary of the available information regarding management of C. burnetii infection in livestock populations. A discussion of currently available testing options and their interpretation is provided, along with recommendations on management practices that can be implemented on‐farm in the face of an outbreak to mitigate losses. Emphasis is placed on biosecurity measures that can be considered for minimizing the zoonotic transmission risk in both field and veterinary facilities.

Bovine Tuberculosis in Britain and Ireland - A Perfect Storm? the Confluence of Potential Ecological and Epidemiological Impediments to Controlling a Chronic Infectious Disease

Successful eradication schemes for bovine tuberculosis (bTB) have been implemented in a number of European and other countries over the last 50 years. However, the islands of Britain and Ireland remain a significant aberration to this trend, with the recent exception of Scotland. Why have eradication schemes failed within these countries, while apparently similar programs have been successful elsewhere? While significant socio-economic and political factors have been discussed elsewhere as key determinants of disease eradication, here we review some of the potential ecological and epidemiological constraints that are present in these islands relative to other parts of Europe. We argue that the convergence of these potential factors may interact additively to diminish the potential of the present control programs to achieve eradication. Issues identified include heterogeneity of diagnostic testing approaches, the presence of an abundant wildlife reservoir of infection and the challenge of sustainably managing this risk effectively; the nature, size, density and network structure of cattle farming; potential effects of Mycobacterium bovis strain heterogeneity on disease transmission dynamics; possible impacts of concurrent endemic infections on the disclosure of truly infected animals; climatological differences and change coupled with environmental contamination. We further argue that control and eradication of this complex disease may benefit from an ecosystem level approach to management. We hope that this perspective can stimulate a new conversation about the many factors potentially impacting bTB eradication schemes in Britain and Ireland and possibly stimulate new research in the areas identified.

Knowledge gaps that hamper prevention and control of Mycobacterium avium subspecies paratuberculosis infection

In the last decades, many regional and country-wide control programmes for Johne's disease (JD) were developed due to associated economic losses, or because of a possible association with Crohn's disease. These control programmes were often not successful, partly because management protocols were not followed, including the introduction of infected replacement cattle, because tests to identify infected animals were unreliable, and uptake by farmers was not high enough because of a perceived low return on investment. In the absence of a cure or effective commercial vaccines, control of JD is currently primarily based on herd management strategies to avoid infection of cattle and restrict within-farm and farm-to-farm transmission. Although JD control programmes have been implemented in most developed countries, lessons learned from JD prevention and control programmes are underreported. Also, JD control programmes are typically evaluated in a limited number of herds and the duration of the study is less than 5 year, making it difficult to adequately assess the efficacy of control programmes. In this manuscript, we identify the most important gaps in knowledge hampering JD prevention and control programmes, including vaccination and diagnostics. Secondly, we discuss directions that research should take to address those knowledge gaps.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): paratuberculosis

Paratuberculosis has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on the eligibility of paratuberculosis to be listed, Article 9 for the categorisation of paratuberculosis according to disease prevention and control rules as in Annex IV and Article 8 on the list of animal species related to paratuberculosis. The assessment has been performed following a methodology composed of information collection and compilation, expert judgement on each criterion at individual and, if no consensus was reached before, also at collective level. The output is composed of the categorical answer, and for the questions where no consensus was reached, the different supporting views are reported. Details on the methodology used for this assessment are explained in a separate opinion. According to the assessment performed, paratuberculosis can be considered eligible to be listed for Union intervention as laid down in Article 5(3) of the AHL. The disease would comply with the criteria in Sections 3, 4 and 5 of Annex IV of the AHL, for the application of the disease prevention and control rules referred to in points (c), (d) and (e) of Article 9(1). The animal species to be listed for paratuberculosis according to Article 8(3) criteria are several species of mammals and birds as susceptible species and some species of the families Bovidae, Cervidae and Leporidae as reservoirs.

Invited review: The economic impact and control of paratuberculosis in cattle

Paratuberculosis (also called Johne's disease) is a chronic disease caused by Mycobacterium avium ssp. paratuberculosis (MAP) that affects ruminants and other animals. The epidemiology of paratuberculosis is complex and the clinical manifestations and economic impact of the disease in cattle can be variable depending on factors such as herd management, age, infection dose, and disease prevalence, among others. Additionally, considerable challenges are faced in the control of paratuberculosis in cattle, such as the lack of accurate and reliable diagnostic tests. Nevertheless, efforts are directed toward the control of this disease because it can cause substantial economic losses to the cattle industry mainly due to increased premature culling, replacement costs, decreased milk yield, reduced feed conversion efficiency, fertility problems, reduced slaughter values, and increased susceptibility to other diseases or conditions. The variability and uncertainty surrounding the estimations of paratuberculosis prevalence and impact influence the design, implementation, and efficiency of control programs in diverse areas of the world. This review covers important aspects of the economic impact and control of paratuberculosis, including challenges related to disease detection, estimations of the prevalence and economic effects of the disease, and the implementation of control programs. The control of paratuberculosis can improve animal health and welfare, increase productivity, reduce potential market problems, and increase overall business profitability. The benefits that can derive from the control of paratuberculosis need to be communicated to all industry stakeholders to promote the implementation of control programs. Moreover, if the suspected link between Johne's disease in ruminants and Crohn's disease in humans was established, significant economic losses could be expected, particularly for the dairy industry, making the control of this disease a priority across dairy industries internationally.

Bacterial Exposures and Associations with Atopy and Asthma in Children

Background

The increase in prevalence of asthma and atopic diseases in Western countries has been linked to aspects of microbial exposure patterns of people. It remains unclear which microbial aspects contribute to the protective farm effect.

Objective

The objective of this study was to identify bacterial groups associated with prevalence of asthma and atopy, and to quantify indoor exposure to some of these bacterial groups.

Methods

A DNA fingerprinting technique, denaturing gradient gel electrophoresis (DGGE), was applied to mattress dust samples of farm children and control children in the context of the GABRIEL Advanced study. Associations between signals in DGGE and atopy, asthma and other allergic health outcomes were analyzed. Quantitative DNA based assays (qPCR) for four bacterial groups were applied on the dust samples to seek quantitative confirmation of associations indicated in DNA fingerprinting.

Results

Several statistically significant associations between individual bacterial signals and also bacterial diversity in DGGE and health outcomes in children were observed. The majority of these associations showed inverse relationships with atopy, less so with asthma. Also, in a subsequent confirmation study using a quantitative method (qPCR), higher mattress levels of specifically targeted bacterial groups - Mycobacterium spp., Bifidobacteriaceae spp. and two different clusters of Clostridium spp. - were associated with a lower prevalence of atopy.

Conclusion

DNA fingerprinting proved useful in identifying bacterial signals that were associated with atopy in particular. These findings were quantitatively confirmed for selected bacterial groups with a second method. High correlations between the different bacterial exposures impede a clear attribution of protective effects to one specific bacterial group. More diverse bacterial flora in mattress dust may link to microbial exposure patterns that protect against development of atopic diseases.

Calves shedding Mycobacterium avium subspecies paratuberculosis are common on infected dairy farms

Mycobacterium avium subspecies paratuberculosis (MAP) causes Johne’s disease, a chronic progressive enteritis. It is generally assumed that calves rarely shed MAP bacteria and that calf-to-calf transmission is of minor importance. The objectives were 1) to estimate the prevalence of MAP-shedding young stock in MAP-infected dairy herds, and identify predictors for test-positive young stock; and 2) to estimate proportions of MAP-contaminated young stock group housing pens and air spaces, and furthermore, identify predictors for test-positive pens. Fecal samples were collected from 2606 young stock on 18 MAP-infected dairy farms. Environmental fecal samples were collected from all group-housing pens and dust samples were collected from all barns. All individual samples were analysed using IS900 and F57 qPCR; fecal samples positive by either PCR and all environmental and dust samples were cultured. Overall, 8.1, 1.2 and 2.0% of cattle were positive on IS900 qPCR, F57 qPCR and bacterial culture, respectively. Young stock housed on farms with culture-positive environmental samples collected from adult cow housing and manure storage had higher odds of testing IS900 qPCR-positive than young stock housed on farms with only negative environmental samples. Furthermore, 14% of collected environmental samples, but no dust samples, were test-positive. Age of cattle in the pen was a significant predictor for environmental sample results. Young stock excreted MAP bacteria in their feces which provided strong evidence for calves as sources of within-herd transmission of MAP on dairy farms known to be infected with this organism.

Dam Mycobacterium avium subspecies paratuberculosis (MAP) infection status does not predetermine calves for future shedding when raised in a contaminated environment: a cohort study

Uptake of Mycobacterium avium subsp. paratuberculosis (MAP) by calves in the first days of life from colostrum, milk and faeces is regarded an important moment of transmission. The objective of this study was to quantify the association between the MAP status of dams as determined by the presence of MAP DNA and antibody in colostrum and that of DNA in faeces and the environment with subsequent MAP shedding of their daughters. A cohort of 117 dam-daughter pairs giving birth/being born on eight commercial dairy farms with endemic paratuberculosis was followed where colostrum, faecal and environmental samples (dust) were analysed for the presence of MAP using an IS900 real-time PCR. Antibodies in colostrum were measured by ELISA. Analysis of dust samples showed that on all farms environmental MAP exposure occurred continuously. In significantly more colostrum samples (48%) MAP DNA was detected compared to faecal samples (37%). MAP specific antibodies were present in 34% of the colostrum samples. In total MAP DNA was present in faecal samples of 41% of the daughters at least once during the sampling period. The association between faecal shedding in the offspring and the dam MAP status defined by MAP PCR on colostrum, MAP PCR on faeces or ELISA on colostrum was determined by an exact cox regression analysis for discrete data. The model indicated that the hazard for faecal shedding in daughters born to MAP positive dams was not significantly different compared to daughters born to MAP negative dams. When born to a dam with DNA positive faeces the HR was 1.05 (CI 0.6; 1.8) and with DNA positive colostrum the HR was 1.17 (CI 0.6; 2.3). When dam status was defined by a combination of both PCR outcomes (faeces and colostrum) and the ELISA outcome the HR was 1.26 (CI 0.9; 1.9). Therefore, this study indicates that neither the presence of MAP DNA in colostrum, MAP DNA in faeces nor the presence of MAP antibodies in colostrum of the dam significantly influences the hazard of MAP shedding in their subsequent daughters up to the age of two years when raised in a contaminated environment.

M. paratuberculosis and Parkinson's disease--is this a trigger

Genetic linkage studies and genome wide analysis have provided insights into complex medical diseases. Mycobacterium avium ss. paratuberculosis (MAP) causes Johne's disease, an important enteric inflammatory disease mostly studied in ruminant animals. MAP is also the putative cause of Crohn's disease. Moreover, MAP has been linked to other inflammatory diseases: sarcoidosis, Blau syndrome, autoimmune diabetes, autoimmune thyroiditis and multiple sclerosis. Genetic studies reveal an association between Parkinson's disease (PD), leprosy and Crohn's disease and since discovered, these findings have been considered "surprising". Autophagy and ubiquitin-proteosome systems are cellular systems that both fight intracellular pathogens (xenophagy) and maintain cellular protein quality control. PD is a common neurodegenerative disease that manifests clinically as a profound movement disorder. The recognized genetic defects of PD create disruption of cellular homeostasis that result in protein folding abnormalities of PD called Lewy bodies. Those same genetic defects are associated with susceptibility to intracellular pathogens, including mycobacteria. It is now understood that PD Lewy body pathology starts in the enteric nervous system and "spreads" to the brain in a retrograde fashion via the vagus nerve. This is the same process by which prions affect the brain. Lewy body pathology of the enteric nervous system predates the Lewy body pathology of the central nervous system (CNS) by years or even decades. This article proposes that genetic defects associated with PD also result in a permissive environment for MAP infection--ineffective xenophagy. It postulates that beginning as an enteric infection, MAP--via the vagus nerve--initiates a pathologic process that results in a targeted neuroinvasion of the CNS. The article proposes that MAP infection and resultant PD pathology are due, in the genetically at-risk and age dependant, to the consumptive exhaustion of the protein quality control systems.

Dose-dependent interferon-gamma release in dairy calves experimentally infected with Mycobacterium avium subspecies paratuberculosis

The interferon-gamma (IFN-γ) release assay is considered useful for diagnosis of subclinical paratuberculosis. However, interpretation can be subjective and complex; therefore, additional information regarding the course of the cellular immune response and effects of age and dose at infection would be helpful. Thirty-three calves were randomly allocated to 10 challenge groups and a negative control group. Calves were inoculated orally at 2 weeks or at 3, 6, 9, or 12 months of age. Within each age group, calves received either a high or low dose of Mycobacterium avium subspecies paratuberculosis (MAP). Monthly blood samples were collected, stimulated with Purified Protein Derivative (PPD) Johnin in vitro, and the subsequent release of IFN-γ measured. Calves inoculated with a high dose had earlier and stronger IFN-γ responses than low-dose calves. Furthermore, calves inoculated at 2 weeks of age produced less IFN-γ compared to those inoculated later in life. The IFN-γ response peaked (on average) 4 months after exposure; therefore, this would be an optimal interval to test cattle for MAP-infection (although the timing of field-based infections is unknown and clearance of infection a possibility). To conclude, the IFN-γ release assay could be a valuable diagnostic test on herd-level to indicate exposure to MAP.

Shedding patterns of dairy calves experimentally infected with Mycobacterium avium subspecies paratuberculosis

Although substantial fecal shedding is expected to start years after initial infection with Mycobacterium avium subspecies paratuberculosis (MAP), the potential for shedding by calves and therefore calf-to-calf transmission is underestimated in current Johne’s disease (JD) control programs. Shedding patterns were determined in this study in experimentally infected calves. Fifty calves were challenged at 2 weeks or at 3, 6, 9 or 12 months of age (6 calves served as a control group). In each age group, 5 calves were inoculated with a low and 5 with a high dose of MAP. Fecal culture was performed monthly until necropsy at 17 months of age. Overall, 61% of inoculated calves, representing all age and dose groups, shed MAP in their feces at least once during the follow-up period. Although most calves shed sporadically, 4 calves in the 2-week and 3-month high dose groups shed at every sampling. In general, shedding peaked 2 months after inoculation. Calves inoculated at 2 weeks or 3 months with a high dose of MAP shed more frequently than those inoculated with a low dose. Calves shedding frequently had more culture-positive tissue locations and more severe gross and histological lesions at necropsy. In conclusion, calves inoculated up to 1 year of age shed MAP in their feces shortly after inoculation. Consequently, there is potential for MAP transfer between calves (especially if they are group housed) and therefore, JD control programs should consider young calves as a source of infection.

Mycobacterium avium Subspecies paratuberculosis: Human Exposure through Environmental and Domestic Aerosols

Mycobacterium avium subspecies paratuberculosis (Map) causes Johne's disease in animals and is significantly associated with Crohn's disease (CD) in humans. Our previous studies have shown Map to be present in U.K. rivers due to land deposition from chronic livestock infection and runoff driven by rainfall. The epidemiology of CD in Cardiff showed a significant association with the River Taff, in which Map can be detected on a regular basis. We have previously hypothesized that aerosols from the river might influence the epidemiology of CD. In this preliminary study, we detected Map by quantitative PCR in one of five aerosol samples collected above the River Taff. In addition, we examined domestic showers from different regions in the U.K. and detected Map in three out of 30 independent samples. In detecting Map in river aerosols and those from domestic showers, this is the first study to provide evidence that aerosols are an exposure route for Map to humans and may play a role in the epidemiology of CD.

Spread of Mycobacterium avium subsp. paratuberculosis through soil and grass on a mouflon (Ovis aries) pasture

The aims of this study were to describe spatial contamination of the environment on a mouflon pasture, as well as to assess the contamination of grass and roots after surface contamination and in depth contamination with feces and buried tissues from animals infected with Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis). Samples of soil, roots, and aerial parts of plants were collected from different locations inside the mouflon pasture, and one control sample site was chosen outside the area where the animals are living. M. a. paratuberculosis DNA was present in all the examined sites and was more often detected in roots than in soil. DNA was detected at up to 80 cm of depth and was spatially more widespread than the initial hypothesis of M. a. paratuberculosis leaching vertically into deeper layers of soil. This study broadens our knowledge of the spread and persistence of M. a. paratuberculosis in an environment with highly infected animals.

From mouth to macrophage: mechanisms of innate immune subversion by Mycobacterium avium subsp. paratuberculosis

Johne’s disease (JD) is a chronic enteric infection of cattle caused by Mycobacterium avium subsp. paratuberculosis (MAP). The high economic cost and potential zoonotic threat of JD have driven efforts to develop tools and approaches to effectively manage this disease within livestock herds. Efforts to control JD through traditional animal management practices are complicated by MAP’s ability to cause long-term environmental contamination as well as difficulties associated with diagnosis of JD in the pre-clinical stages. As such, there is particular emphasis on the development of an effective vaccine. This is a daunting challenge, in large part due to MAP’s ability to subvert protective host immune responses. Accordingly, there is a priority to understand MAP’s interaction with the bovine host: this may inform rational targets and approaches for therapeutic intervention. Here we review the early host defenses encountered by MAP and the strategies employed by the pathogen to avert or subvert these responses, during the critical period between ingestion and the establishment of persistent infection in macrophages.

Boot swabs to collect environmental samples from common locations in dairy herds for Mycobacterium avium ssp. paratuberculosis (MAP) detection

The aim of the present study was the examination of the boot swab sampling technique for the collection of environmental material in order to identify Mycobacterium avium ssp. paratuberculosis (MAP)-infected herds. Eight dairy herds were included into the study. Four of them had a well-known history of MAP-infection from a herd surveillance programme conducted since 2006. Cows in these herds were repeatedly tested positive in Pourquier® MAP-ELISA (Pourquier, Montepellier, France); in some MAP could be isolated in individual faecal culture despite that symptoms of paratuberculosis were never reported. In four presumably negative herds nearly all cows were repeatedly tested serologically negative for MAP. The pathogen was never isolated from faecal samples of cows by culture. The study was initiated with the aim of standardising environmental samples as a herd diagnostics, in which overall 130 pairs of boot swab samples from the cows' surroundings were taken In 58 of 64 swab samples (90·6%) from confirmed MAP-infected herds the organism could be isolated by mycobacterial culture of the boot swab. Contrarily, in 66 samples from presumably MAP-negative herds only one swab was positive (1·5%). The utilisation of boot swabs as a standardised technique for environmental sampling offers an effective and inexpensive tool for identifying herds infected with MAP. This is the first report of using boot swabs for the collection of environmental samples for MAP- detection in cattle herds. This easy to perform technique enables the economical detection of MAP herd status.

Evaluation of age-dependent susceptibility in calves infected with two doses of Mycobacterium avium subspecies paratuberculosis using pathology and tissue culture

The longstanding assumption that calves of more than 6 months of age are more resistant to Mycobacterium avium subspecies paratuberculosis (MAP) infection has recently been challenged. In order to elucidate this, a challenge experiment was performed to evaluate age- and dose-dependent susceptibility to MAP infection in dairy calves. Fifty-six calves from MAP-negative dams were randomly allocated to 10 MAP challenge groups (5 animals per group) and a negative control group (6 calves). Calves were inoculated orally on 2 consecutive days at 5 ages: 2 weeks and 3, 6, 9 or 12 months. Within each age group 5 calves received either a high - or low - dose of 5 × 10⁹ CFU or 5 × 10⁷ CFU, respectively. All calves were euthanized at 17 months of age. Macroscopic and histological lesions were assessed and bacterial culture was done on numerous tissue samples. Within all 5 age groups, calves were successfully infected with either dose of MAP. Calves inoculated at < 6 months usually had more culture-positive tissue locations and higher histological lesion scores. Furthermore, those infected with a high dose had more severe scores for histologic and macroscopic lesions as well as more culture-positive tissue locations compared to calves infected with a low dose. In conclusion, calves to 1 year of age were susceptible to MAP infection and a high infection dose produced more severe lesions than a low dose.

Relationship between presence of cows with milk positive for Mycobacterium avium subsp. paratuberculosis-specific antibody by enzyme-linked immunosorbent assay and viable M. avium subsp. paratuberculosis in dust in cattle barns

Paratuberculosis, or Johne's disease, in cattle is caused by Mycobacterium avium subsp. paratuberculosis, which has recently been suspected to be transmitted through dust. This longitudinal study on eight commercial M. avium subsp. paratuberculosis-positive dairy farms studied the relationship between the number of cows with M. avium subsp. paratuberculosis antibody-positive milk and the presence of viable M. avium subsp. paratuberculosis in settled-dust samples, including their temporal relationship. Milk and dust samples were collected in parallel monthly for 2 years. M. avium subsp. paratuberculosis antibodies in milk were measured by enzyme-linked immunosorbent assay (ELISA) and used as a proxy for M. avium subsp. paratuberculosis shedding. Settled-dust samples were collected by using electrostatic dust collectors (EDCs) at six locations in housing for dairy cattle and young stock. The presence of viable M. avium subsp. paratuberculosis was identified by liquid culture and PCR. The results showed a positive relationship (odds ratio [OR], 1.2) between the number of cows with ELISA-positive milk and the odds of having positive EDCs in the same airspace as the adult dairy cattle. Moreover, the total number of lactating cows also showed an OR slightly above 1. This relationship remained the same for settled-dust samples collected up to 2 months before or after the time of milk sampling. The results suggest that removal of adult cows with milk positive for M. avium subsp. paratuberculosis-specific antibody by ELISA might result in a decrease in the presence of viable M. avium subsp. paratuberculosis in dust and therefore in the environment. However, this decrease is likely delayed by several weeks at least. In addition, the data support the notion that M. avium subsp. paratuberculosis exposure of young stock is reduced by separate housing.

Mycobacterium avium subspecies paratuberculosis is widely distributed in British soils and waters: implications for animal and human health

In the first comprehensive geographical survey of distribution in Great Britain, Mycobacterium avium ssp. paratuberculosis (MAP) was detected in 115 of 1092 (10.5%) soil cores, in the range of 5 × 10(2) to 3 × 10(6) MAP cell equivalents (CE) g(-1) wet weight soil with the majority of the positive PCR reactions (n = 75; 65%) occurring around the limit of detection (500-5000 CE g(-1) wet weight soil). The distribution of MAP significantly increased from North to South and was significantly correlated with increasing cattle numbers over the same longitudinal axis. Similarly MAP occurrence significantly increased towards easterly latitudes although none of the parameters measured were associated. Comparisons of land use indicated that MAP was widely distributed in both farming and non-farming areas. Soil core samples taken from the rivers Wyre and Douglas catchments (Lancashire, UK) and river Tywi (South Wales) were negative for MAP. However, river monitoring showed a consistent presence of MAPs throughout those catchments over a 6-month period. We concluded that MAP is widely distributed within and outside the confines of the farming environment; its geographical distribution is wider than originally anticipated and; monitoring rivers describes the MAP status of catchment better than individual soil samples.

Pathological findings in young and adult sheep following experimental infection with 2 different doses of Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subsp paratuberculosis (Map) is assumed to infect young ruminants; however, little is known concerning the possibility of adult animals becoming infected. An experimental infection was conducted to establish the effect of age and doses of Map on susceptibility to paratuberculosis in sheep. Sixteen of twenty-four 1.5-month-old Churra lambs and 23 of 30 adult ewes (from 2-11 years old) were orally challenged with an ovine field strain of Map. Thirteen ewes and 8 lambs were infected with a high dose (HD) and 10 adult sheep and 8 lambs with a low dose (LD) of Map. The remaining animals were unchallenged controls. Animals were euthanized at 110 to 120 and 210 to 220 days postinfection. Histological, bacteriological, and nested polymerase chain reaction (PCR) studies were conducted in samples of intestine and related lymphoid tissue (Peyer patches, lymph nodes). Animals were classified according to their lesions. The number of granulomas was counted in 3 tissue sections from each sample. Only the HD groups showed lesions associated with paratuberculosis (92.3% of ewes and 100% of lambs). Adults had lesions characterized by few small demarcated focal granulomas restricted to the lymphoid tissue, whereas granulomas were more numerous and larger, appearing in the lamina propria unrelated to lymphoid tissue, in the lambs. Only HD-infected lambs were positive to culture, whereas nested PCR also detected positive HD ewes and some LD animals. These results suggest that adult sheep can become infected by Map, as seen by the development of lesions, but they are focal and restricted to the lymphoid tissue.

Distribution of Mycobacterium avium ssp. paratuberculosis in a German zoological garden determined by IS900 semi-nested and quantitative real-time PCR

Little data concerning the distribution of Mycobacterium avium ssp. paratuberculosis (MAP) in zoological gardens is available. The presence of MAP in captured wildlife might provide further information on non-ruminant hosts and expand the list of animals susceptible to MAP being potential sources of MAP transmission. Therefore, a German zoological garden with recent history of clinical paratuberculosis in Barbary sheep (Ammotragus lervia) and an alpaca (Lama pacos) was selected to estimate the distribution of MAP infections in 21 mammalian and avian species. Pooled faecal samples from individual animals of each species were tested for the presence of MAP. A previously developed IS900 semi-nested PCR (snPCR) assay, amplifying a 587 bp and a 278 bp fragment, was used for the detection of MAP-DNA. Based on this snPCR, in 14 out of the 21 pooled faecal samples MAP-DNA was detected. MAP positive snPCR results were observed in ruminants and camelids as well as in non-ruminants such as equines, primates, rodents, and birds. Moreover, a quantitative real-time PCR demonstrated that the concentration of MAP-DNA was within the range of 2.2 × 10(3)-9.6 × 10(6) MAP-DNA equivalents per gram faeces. The highest amount was shed by primates such as Black-and-white ruffed lemurs (Varecia variegata) and Cottontop tamarins (Saguinus oedipus). This is the first survey investigating the presence of MAP in a German zoo, which includes non-ruminants. The results of the present study confirm the wide host range of MAP and demonstrate that MAP occurs more frequently in zoo animals than expected. In order to restrict further spread of MAP in European zoos, additional investigations regarding the existing transmission pathways of MAP in zoos are recommended.

Culture- and quantitative IS900 real-time PCR-based analysis of the persistence of Mycobacterium avium subsp. paratuberculosis in a controlled dairy cow farm environment

The aim of this study was to monitor the persistence of Mycobacterium avium subsp. paratuberculosis in environmental samples taken from a Holstein farm with a long history of clinical paratuberculosis. A herd of 606 head was eradicated, and mechanical cleaning and disinfection with chloramine B with ammonium (4%) was carried out on the farm; in the surrounding areas (on the field and field midden) lime was applied. Environmental samples were collected before and over a period of 24 months after destocking. Only one sample out of 48 (2%) examined on the farm (originating from a waste pit and collected before destocking) was positive for M. avium subsp. paratuberculosis by cultivation on solid medium (Herrold's egg yolk medium). The results using real-time quantitative PCR (qPCR) showed that a total of 81% of environmental samples with an average mean M. avium subsp. paratuberculosis cell number of 3.09 × 10(3) were positive for M. avium subsp. paratuberculosis before destocking compared to 43% with an average mean M. avium subsp. paratuberculosis cell number of 5.86 × 10(2) after 24 months. M. avium subsp. paratuberculosis-positive samples were detected in the cattle barn as well as in the calf barn and surrounding areas. M. avium subsp. paratuberculosis was detected from different matrices: floor and instrument scrapings, sediment, or scraping from watering troughs, waste pits, and cobwebs. M. avium subsp. paratuberculosis DNA was also detected in soil and plants collected on the field midden and the field 24 months after destocking. Although the proportion of positive samples decreased from 64% to 23% over time, the numbers of M. avium subsp. paratuberculosis cells were comparable.

Within-farm transmission of bovine paratuberculosis: recent developments

Mycobacterium avium subspecies paratuberculosis is the causative agent of paratuberculosis in cattle which causes a chronic infection of the small intestine. Since the transmission is only partly understood current control programs have been able to only decrease prevalence but not to eradicate disease from a herd. Unknown and therefore uncontrolled routes of transmission were suggested and infective bioaerosols were hypothesized as a potential candidate. This review gives an overview concerning disease transmission and focuses on consequences of bioaerosols on the within-herd transmission of paratuberculosis.

Epidemiology and economics of paratuberculosis

Johne’s disease is the clinical manifestation of Mycobacterium avium subsp. paratuberculosis (MAP) infection and has become widespread since it was first observed in the United States in the early 1900s. MAP is primarily spread through the fecal-oral route, and herds generally become infected by unknowingly purchasing infected animals. The economic losses from the disease are primarily due to decreased milk production, decreased weaning weights in nursing young stock, increased replacement costs, and decreased slaughter value.

Intestinal infection following aerosol challenge of calves with Mycobacterium avium subspecies paratuberculosis

A challenge experiment was performed to investigate whether administration of Mycobacterium avium subsp. paratuberculosis (MAP) via the respiratory route leads to MAP infection in calves. Eighteen calves from test negative dams were randomly allocated to four groups. Six calves were challenged with MAP nasally and six calves were challenged by transtracheal injection; three orally challenged calves served as positive controls, and three non challenged calves as negative controls. The challenge was performed as a nine-fold trickle dose, 10⁷ CFU in total. Blood and faecal samples were collected frequently. Calves were euthanized three months post-challenge and extensively sampled. Blood samples were tested for the presence of antibodies and interferon gamma producing cells by ELISA. Faecal and tissue samples were cultured in a liquid culture system and the presence of MAP was confirmed by IS900 realtime PCR. Fourteen out of fifteen calves had no MAP antibody response. The negative controls remained negative; all positive controls became infected. Two nasally challenged calves showed a Purified Protein Derivative Avian (PPDA) specific interferon gamma response. In all nasally challenged calves, MAP positive intestinal samples were detected. In three calves of the nasal group MAP positive retropharyngeal lymph nodes or tonsils were detected. In all calves of the transtracheal group MAP positive intestinal tissues were detected as well and three had a MAP positive tracheobronchial lymph node. These findings indicate that inhalation of MAP aerosols can result in infection. These experimental results may be relevant for transmission under field conditions since viable MAP has been detected in dust on commercial dairy farms.

Differences in the peripheral immune response between lambs and adult ewes experimentally infected with Mycobacterium avium subspecies paratuberculosis

The peripheral immune response, and its relationship with the outcome of the infection according to the age of the animal, has been investigated in young lambs and adult ewes experimentally infected with two different doses of Mycobacterium avium subspecies paratuberculosis (Map). Sixteen 1.5-month-old lambs out of 24 and 23 adult ewes out of 30 were orally challenged with an ovine Map field isolate. Animals were divided into two groups: HD, infected with a higher dose of Map and LD, with a lower dose. The remaining animals were used as uninfected control groups. Animals were euthanized at 110-120 and 210-220 days post-infection (dpi). Along the experiment, the humoral response and the specific and non-specific IFN-γ production were assessed. An intradermal skin test (IDT), using avian PPD, was also performed at 90 and 195 dpi. Samples of intestine and related lymphoid tissue were taken for histological, bacteriological and PCR studies. The Ab and IFN-γ production as well as the IDT response appeared earlier and with more intensity in the adult ewes compared to the lambs. The basal non-specific IFN-γ levels increased only in the adult ewes from the HD group. Animals from the LD and HD groups were positive to PCR; however, lesions consistent with paratuberculosis were exclusively observed in the HD group, both in lambs and in adult sheep, but they only progressed to more advanced stages in the former. These results suggest that the peripheral immune response induced by Map infection in the adult ewes is more efficient to control the progression of the infection than in lambs. This could likely be due to the existence of previous contacts with Map or other mycobacteria in the adult sheep compared to the young lambs.

Reduction of Coxiella burnetii prevalence by vaccination of goats and sheep, The Netherlands

Recently, the number of human Q fever cases in the Netherlands increased dramatically. In response to this increase, dairy goats and dairy sheep were vaccinated against Coxiella burnetii. All pregnant dairy goats and dairy sheep in herds positive for Q fever were culled. We identified the effect of vaccination on bacterial shedding by small ruminants. On the day of culling, samples of uterine fluid, vaginal mucus, and milk were obtained from 957 pregnant animals in 13 herds. Prevalence and bacterial load were reduced in vaccinated animals compared with unvaccinated animals. These effects were most pronounced in animals during their first pregnancy. Results indicate that vaccination may reduce bacterial load in the environment and human exposure to C. burnetii.

Mycobacterium avium subspecies paratuberculosis in bioaerosols after depopulation and cleaning of two cattle barns

Settled dust samples were collected on a commercial dairy farm in the Netherlands with a high prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) (barn A) and on a Dutch experimental cattle farm (barn B) stocked with cattle confirmed to be MAP shedders. Barns were sampled while animals were present, after both barns were destocked and cleaned by cold high-pressure cleaning, and after being kept empty for two weeks (barn A) or after additional disinfection (barn B). MAP DNA was detected by IS900 real-time PCR and viable MAP were detected by liquid culture. MAP DNA was detected in 78 per cent of samples from barn A and 86 per cent of samples from barn B collected while animals were still present. Viable MAP was detected in six of nine samples from barn A and in three of seven samples from barn B. After cold high-pressure cleaning, viable MAP could be detected in only two samples from each barn. After leaving barn A empty for two weeks, and following additional disinfection of barn B, no viable MAP could be detected in any settled dust sample.

Presence of Mycobacterium avium subsp. paratuberculosis in environmental samples collected on commercial Dutch dairy farms

Mycobacterium avium subsp. paratuberculosis, the causative agent of Johne's disease in cattle, was identified in settled-dust samples of Dutch commercial dairy farms, both in the dairy barn and in the young stock housing. Bioaerosols may play a role in within-farm M. avium subsp. paratuberculosis transmission.