RESUMO
INTRODUCTION: Ovine foot rot is a highly contagious and multifactorial claw disease, caused by Dichelobacter nodosus (D. nodosus) and is the main cause of lameness in sheep. The aim of this cross-sectional study was to determine the prevalence of D. nodosus in western Austria both at animal and farm levels. Real-time PCR was evaluated in comparison with clinical and bacteriological investigations from interdigital foot swabs to detect D. nodosus-infected animals. In addition, the use of pooled four-foot swabs to detect foot rot was determined. In course of the study a total of 3156 sheep from 124 farms were examined for lameness and clinical signs of foot rot. The found flock prevalence of D. nodosus was 30,65 % with bacterial culture showing a sensitivity of 75,0 % and a specificity of 100,0 % (p < 0,001) respectively, compared with PCR. Furthermore, clinical foot rot scores (Ckorr = 0,87; p < 0,001) and lameness scores (Ckorr = 0,71; p < 0,001) highly correlated with the detection of D. nodosus by PCR. The result showed that the clinical examination can be used to identify animals infected with D. nodosus in flocks, but PCR must be used to confirm the diagnosis. D. nodosus could be detected equally well with risk-based pools-of-five samples as with undiluted samples (p < 0,001), suggesting that a pool-of-five samples might be a suitable and cost-effective method for detecting D. nodosus in sheep flocks. This study provides an overview of foot rot in Tyrolean sheep flocks and outlines the possibilities and limitations of the various diagnostic tools for D. nodosus. Further studies to investigate possible influencing factors, including alpine pasturing, management factors and biosecurity predisposing to foot rot are necessary for the design of effective future control programs in alpine regions.
INTRODUCTION: Le piétin ovin est une maladie des onglons hautement contagieuse et multifactorielle, causée par Dichelobacter nodosus (D. nodosus) qui constitue la principale cause de boiterie chez les ovins. L'objectif de cette étude transversale était de déterminer la prévalence de D. nodosus dans l'ouest de l'Autriche, tant au niveau de l'animal que de l'exploitation. La PCR en temps réel a été évaluée en comparaison avec les examens cliniques et bactériologiques effectués à partir d'écouvillons des espaces interdigités pour détecter les animaux infectés par D. nodosus. En outre, l'utilisation d'un pool d'écouvillons des quatre membres pour détecter le piétin a été déterminée. Au cours de l'étude, un total de 3156 moutons provenant de 124 fermes ont été examinés pour détecter des boiteries et des signes cliniques de piétin. La prévalence de D. nodosus dans les troupeaux était de 30,65 %, la culture bactérienne montrant une sensibilité de 75 % et une spécificité de 100 % (p < 0,001), respectivement, par rapport à la PCR. En outre, les scores cliniques de piétin (Ckorr = 0,87; p < 0,001) et les scores de boiterie (Ckorr = 0,71; p < 0,001) étaient fortement corrélés avec la détection de D. nodosus par PCR. Les résultats montrent que l'examen clinique peut être utilisé pour identifier les animaux infectés par D. nodosus dans les troupeaux mais que la PCR doit être utilisée pour confirmer le diagnostic. D. nodosus a pu être détecté aussi bien avec des pools de cinq échantillons basés sur le risque qu'avec des échantillons non dilués (p < 0,001), ce qui suggère qu'un pool de cinq échantillons pourrait être une méthode appropriée et rentable pour détecter D. nodosus dans les troupeaux de moutons. Cette étude donne un aperçu du piétin dans les troupeaux de moutons tyroliens et souligne les possibilités et les limites des différents outils de diagnostic pour D. nodosus. D'autres études visant à examiner les facteurs d'influence possibles, y compris les pâturages alpins, les facteurs de gestion et la biosécurité prédisposant au piétin, sont nécessaires pour la conception de futurs programmes de contrôle efficaces dans les régions alpines.
Assuntos
Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos , Infecções por Bactérias Gram-Negativas , Coxeadura Animal , Doenças dos Ovinos , Animais , Dichelobacter nodosus/genética , Dichelobacter nodosus/isolamento & purificação , Pododermatite Necrótica dos Ovinos/microbiologia , Pododermatite Necrótica dos Ovinos/epidemiologia , Pododermatite Necrótica dos Ovinos/diagnóstico , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/microbiologia , Doenças dos Ovinos/diagnóstico , Ovinos , Coxeadura Animal/epidemiologia , Coxeadura Animal/microbiologia , Coxeadura Animal/diagnóstico , Áustria/epidemiologia , Estudos Transversais , Prevalência , Infecções por Bactérias Gram-Negativas/veterinária , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/microbiologia , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reação em Cadeia da Polimerase/veterinária , Reação em Cadeia da Polimerase/métodos , Sensibilidade e EspecificidadeRESUMO
In the Portuguese Alentejo region, Merino sheep breed is the most common breed, reared for the production of meat, dairy, and wool. Footrot is responsible for lameness, decreased animal welfare, and higher production losses, generating a negative economic impact. The disease is caused by Dichelobacter nodosus that interacts with the sheep foot microbiome, to date largely uncharacterized. In fact, Dichelobacter nodosus is not able to induce footrot by itself being required the presence of a second pathogen known as Fusobacterium necrophorum. To understand and characterize the footrot microbiome dynamics of different footrot lesion scores, a whole metagenome sequencing (WMGS) approach was used. Foot tissue samples were collected from 212 animals with different degrees of footrot lesion scores, ranging from 0 to 5. Distinct bacterial communities were associated with feet with different footrot scores identifying a total of 63 phyla and 504 families. As the severity of footrot infection increases the microorganisms' diversity decreases triggering a shift in the composition of the microbiome from a dominant gram-positive in mild stages to a dominant gram-negative in the severe stages. Several species previously associated with footrot and other polymicrobial diseases affecting the epidermis and provoking inflammatory responses such as Treponema spp., Staphylococcus spp., Streptococcus spp. and Campylobacter spp. were identified proliferating along with the lesions' severity. Although these bacteria are not able to initiate footrot, several evidences have been described supporting their association with the severity and incidence increase of footrot lesions caused by Dichelobacter nodosus and Fusobacterium necrophorum. Further investigation is required to establish the roles of particular taxa and identify which of them play a role in the disease process and which are opportunistic pathogens.
Assuntos
Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos , Infecções por Bactérias Gram-Negativas , Microbiota , Doenças dos Ovinos , Animais , Ovinos , Doenças dos Ovinos/microbiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Fusobacterium necrophorum , Dichelobacter nodosus/genética , Bactérias/genética , Carneiro Doméstico , Microbiota/genética , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/veterináriaRESUMO
In many countries, sheep lameness is a cause of economic concern and a contributing factor to a declining economy. This study aimed to investigate changes in procalcitonin (PCT), acute phase proteins (APPs), and cytokines (CYTs) in response to interdigital dermatitis and footrot in sheep under field conditions, to emphasize their role in the disease pathogenesis, diagnosis, as well as monitoring treatment response. Fifty-three sheep with foot diseases (26 clinical cases with interdigital dermatitis and 27 clinical cases with footrot) and 20 clinically healthy naemi sheep were used in this study. Real time PCR for detection of Fusobacterium necrophorum (F. necrophorum) and Dichelobacter nodosus (D. nodosus) revealed that, all samples collected from lame sheep (N = 53) were positive for D. nodosus (100 %), whereas F. necrophorum was detected in 19 out of 53 samples (35.84 %). The virulent D. nodosus was detected in 48 lameness cases where non-virulent D. nodosus were identified in 5 cases (in concurrent with F. necrophorum). The mean serum levels of PCT, C-reactive protein (CRP), serum amyloid A (SAA), haptoglobin (HP), fibrinogen (Fg) and CYTs (IL1-ß, IL-1α, IFN-γ, IL-6 and TNF-α) in sheep with clinical interdigital dermatitis and footrot were remarkably higher than those detected in control healthy sheep. The serum levels of PCT, CRP, SAA, HP, Fg, and CYTs markers in lame sheep pre- and post-treatment were measured. A substantial decline was detected in serum levels of tested biomarkers of lame sheep after 14 days of treatment. The ROC curves were created. The AUC was assessed to evaluate the accuracy of each variable in distinguishing diseased and healthy sheep. Based on the ROC curves and AUCs; PCT, CRP, SAA, HP, and CYTs were highly diagnostic and predictive for the treatment response of sheep with clinical interdigital dermatitis and footrot. Moreover, all tested biomarkers had a noteworthy role in disease immuno-pathogenesis. Nevertheless, PCT and CRP are better than other tested APPs and CYTs as diagnostic markers for interdigital dermatitis and footrot. However, PCT only has the ability to differentiate sheep with different lameness score.
Assuntos
Dermatite , Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos , Doenças dos Ovinos , Ovinos , Animais , Pró-Calcitonina , Coxeadura Animal/microbiologia , Proteínas de Fase Aguda , Citocinas , Doenças dos Ovinos/microbiologia , Pododermatite Necrótica dos Ovinos/diagnóstico , Pododermatite Necrótica dos Ovinos/microbiologia , Pododermatite Necrótica dos Ovinos/patologia , Dermatite/microbiologia , Dermatite/veterináriaRESUMO
Ovine footrot, is a highly contagious polymicrobial bacterial infection, primarily caused by Dichelobacter nodosus. Preventative bactericidal footbaths are commonly used in the sheep industry to reduce the spread of bacteria. However, their effect on the bacterial community is poorly understood. This is the first study to investigate the impact of 2% Digicur (ProGiene,UK) footbath on the bacterial community of the ovine interdigital skin following a common UK footbathing routine. Swab samples were analysed by qPCR to determine prevalence and load of D. nodosus and numerated on MacConkey agar in the presence or absence of tetracycline and ampicillin to determine phenotypic antimicrobial resistance. Metagenomics were used to determine the impact of a single footbath on the bacterial community and genotypic antimicrobial resistance. The results suggest 2% Digicur is ineffective at reducing the load of D. nodosus when applied as a one off or weekly footbath, however sheep may act as a reservoir for multi-drug resistant bacteria creating opportunities to spread antimicrobial resistance to other sheep and their environment.
Assuntos
Anti-Infecciosos , Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos , Infecções por Bactérias Gram-Negativas , Doenças dos Ovinos , Animais , Anti-Infecciosos/farmacologia , Dichelobacter nodosus/genética , Pododermatite Necrótica dos Ovinos/epidemiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Glutaral/farmacologia , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Prevalência , Ovinos , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/microbiologiaRESUMO
Ovine footrot is a highly contagious foot disease caused by the gram-negative bacterium Dichelobacter nodosus (D. nodosus). In a recent report, we showed a prevalence of 42.9% D. nodosus positive swabs across Germany. In this follow-up study, we used real-time PCR results for D. nodosus and footrot scores of 9297 sheep from 208 flocks and collated these data with survey data on herd and animal characteristics and herd management. The aims of the present study were to investigate herd and animal factors associated with D. nodosus infection and footrot scores in individual sheep. Multivariable analyses with generalized mixed models showed that month of recording, breed, herdbook membership, use of antibiotics, and footbaths in the past 3-10 years, signs of footrot in the past 12 months and flock environment of the sheep, modelled as a random farm effect within region, were significant risk factors. Among the 21 different breeds, Romney had the lowest risk of D. nodosus infection, while Swifter had the highest risk and German Merino and German White Heath were the next breeds at highest risk of D. nodosus infection. The variance between farms in the prevalence of D. nodosus was large and accounted for 84% of the total variance in the mixed model analysis. We conclude that specific and as yet unknown effects influencing D. nodosus infections in flocks, as well as breed and weather, are the most important effects on D. nodosus infection in sheep, pointing towards the need to establish adequate infection control at farm level.
Assuntos
Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos , Infecções por Bactérias Gram-Negativas , Doenças dos Ovinos , Animais , Dichelobacter nodosus/genética , Seguimentos , Pododermatite Necrótica dos Ovinos/epidemiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/veterinária , Fatores de Risco , Ovinos , Doenças dos Ovinos/microbiologia , Carneiro DomésticoRESUMO
Genetic evaluations utilising footrot scores from industry flocks in their essence, incorporate data from a wide range of challenge environments, resulting in potentially large differences in means, variances and distribution of scores across challenges. The date that commencement of infection occurs is generally unknown, and progression of the infection varies with the prevailing environmental and management conditions, virulence of the bacterium Dichelobacter nodosus, as well as the genetic potential and (permanent) environmental ability of animals to resist footrot. In practice, animals are unlikely to be repeatedly scored to identify the best time for comparison, or monitor development of disease progression. Furthermore, field challenges are limited by the need to treat animals before their welfare is compromised. Therefore, the duration and intensity of infection varies and this affects comparisons between animals for their susceptibility. Diseases such as footrot are characterised by multiple categorical scores reflecting clinical stages that describe the progression and relative impact of the disease. This provides the opportunity for the transformation of the data to a standardised prevalence. Scoring events from multiple footrot field challenges under a standardised protocol were used to establish a series of transition matrices to describe disease progression between scores over time. These transition matrices were used to standardise challenge events to the more severe scoring events, observed later in the challenge. The accuracy of the transition technique was tested by comparing the ranking of animals and sires against the observed scores. Transitioning the data from low disease prevalence to the higher prevalence at the subsequent scoring event improved the correlations between the scoring events, at the animal level, by upwards of 0.10 across challenges. The utilisation of a transition matrix to transform low prevalence disease challenges by taking into account the natural biological rate of progression through the clinical stages of the disease provides a more accurate technique to account for variation in disease prevalence. The transition technique increases the acceptable range of disease expression targeted by producers when scoring virulent footrot challenges reducing the need for repeat scoring and allowing earlier treatment and reducing the impact of the disease on the host animal.
Assuntos
Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos , Doenças dos Ovinos , Animais , Dichelobacter nodosus/genética , Progressão da Doença , Pododermatite Necrótica dos Ovinos/tratamento farmacológico , Pododermatite Necrótica dos Ovinos/epidemiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Ovinos/genética , Doenças dos Ovinos/genética , Doenças dos Ovinos/microbiologia , VirulênciaRESUMO
BACKGROUND: Ovine footrot and contagious ovine digital dermatitis (CODD) are contagious mixed bacterial infections with major impacts on animal health and production. In Sweden, ovine footrot and CODD were first detected in 2004 and 2019, respectively. In 2009, a voluntary control programme for footrot was established, and a prevalence study in slaughter lambs was conducted, however, the distribution of footrot and CODD-associated bacteria is still unknown. This study examined the prevalence of Dichelobacter nodosus, Fusobacterium necrophorum and Treponema spp., as well as the current prevalence of footrot and CODD, in Swedish slaughter lambs. RESULTS: A total of 2048 feet, from 512 slaughter lambs, were collected from eight slaughterhouses throughout Sweden in autumn 2020. All feet were visually examined for lesions of footrot and CODD and sampled for subsequent real-time polymerase chain reaction (PCR) analysis. Nine lambs (1.8%) had at least one foot affected with footrot (footrot score ≥ 2). A CODD grade 1 lesion was detected in a single lamb (0.2%). The prevalence of D. nodosus, F. necrophorum and Treponema spp. was 6.1%, 7.6% and 90.6%, respectively. The D. nodosus detected were benign strains. CONCLUSIONS: The prevalence of footrot in Swedish slaughter lambs has been significantly reduced, from 5.8 to 1.8%, during the past 11 years. This indicates that preventive measures, such as the national control programme and elimination of footrot from affected flocks, have been effective. A single lamb (0.2%) was found with a CODD lesion (grade 1). In Sweden, benign rather than virulent strains of D. nodosus seem to be the most common. Neither D. nodosus nor F. necrophorum were widespread among Swedish slaughter lambs, but both were more likely to be found in lambs with footrot. Treponema spp. was very commonly found in lambs with and without footrot, but there is a lack of information on the individual Treponema spp. present in Swedish slaughter lambs and their potential pathogenicity.
Assuntos
Dichelobacter nodosus , Dermatite Digital , Pododermatite Necrótica dos Ovinos , Doenças dos Ovinos , Animais , Dermatite Digital/epidemiologia , Dermatite Digital/microbiologia , Pododermatite Necrótica dos Ovinos/epidemiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Pododermatite Necrótica dos Ovinos/patologia , Prevalência , Ovinos , Doenças dos Ovinos/microbiologia , Carneiro Doméstico , Suécia/epidemiologiaRESUMO
Fusobacterium necrophorum, a Gram-negative anaerobe, is an important bovine pathogen that causes hepatic abscesses, foot rot, mastitis and endometritis. We have previously shown that the 43 kDa outer membrane protein (43 K OMP) of F. necrophorum is a porin protein that plays an important role in bacterial infections; however, the molecular mechanisms by which this protein mediates adhesion remain unclear. In this study, we investigated the role of 43 K OMP in F. necrophorum adhesion to bovine epithelial cells using 43 K OMP-deficient mutants, and identified the protein that interacts with 43 K OMP by immunoprecipitation-mass spectrometry. Our results indicated that the native 43 K OMP and recombinant 43 K OMP could bind to the cell membrane of MAC-T or bovine endometrial epithelial cells (BEECs). When F. necrophorum was preincubated with antibodies against the recombinant 43 K OMP or bovine epithelial cells were preincubated with 43 K OMP, the adhesion of F. necrophorum to MAC-T or BEECs decreased significantly (P<0.01). We successfully constructed a 43 K OMP-deficient strain (A25Δ43 K OMP) and bacterial attachment to MAC-T or BEECs was significantly higher with the F. necrophorum A25 strain than with mutant strain A25Δ43 K OMP (P<0.01). The deficiency of 43 K OMP reduced the binding of F. necrophorum to bovine epithelial cells by 90.5 %-94.9 %. Among the 39 potential differential proteins, fibronectin, collagen and myosin were selected as the target proteins, and direct interaction between 43 K OMP of F. necrophorum and fibronectin was demonstrated. Taken together, these results suggest that 43 K OMP plays a key role in adhesion of F. necrophorum to bovine epithelial cells through its interaction with fibronectin. These findings provide a theoretical basis for the pathogenic mechanism of F. necrophorum.
Assuntos
Doenças dos Bovinos , Pododermatite Necrótica dos Ovinos , Infecções por Fusobacterium , Animais , Bovinos , Doenças dos Bovinos/microbiologia , Células Epiteliais , Feminino , Fibronectinas/metabolismo , Pododermatite Necrótica dos Ovinos/microbiologia , Infecções por Fusobacterium/microbiologia , Infecções por Fusobacterium/veterinária , Fusobacterium necrophorum/genéticaRESUMO
The Mediterranean climate region of Alentejo in the Southern of Portugal is an important sheep production centre but little is known about the presence and characteristics of Dichelobacter nodosus in association with Fusobacterium necrophorum in the different footrot lesion scores. DNA from 261 interdigital biopsy samples, taken from 14 footrot affected flocks and from three non-affected flocks, were analysed for the presence of D. nodosus and F. necrophorum by real-time PCR. Both virulence and serogroup were determined for 132 and 53 D. nodosus positive biopsy samples, respectively. The co-infection with both bacteria was the commonest epidemiological finding associated with a greater disease severity. There was a statistically significant association (p = 0.002) between footrot-affected flocks and the presence of D. nodosus. Most D. nodosus positive samples were virulent (96.2 %) and belonged to serogroup B (90 %).
Assuntos
Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos , Doenças dos Ovinos , Animais , Dichelobacter nodosus/genética , Pododermatite Necrótica dos Ovinos/epidemiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Fusobacterium necrophorum/genética , Portugal/epidemiologia , Ovinos , Doenças dos Ovinos/microbiologiaRESUMO
Footrot is a polymicrobial infectious disease in sheep causing severe lameness, leading to one of the industry's largest welfare problems. The complex etiology of footrot makes in situ or in vitro investigations difficult. Computational methods offer a solution to understanding the bacteria involved and how they may interact with the host, ultimately providing a way to identify targets for future hypothesis-driven investigative work. Here, we present the first combined global analysis of bacterial community transcripts together with the host immune response in healthy and diseased ovine feet during a natural polymicrobial infection state using metatranscriptomics. The intratissue and surface bacterial populations and the most abundant bacterial transcriptomes were analyzed, demonstrating that footrot-affected skin has reduced diversity and increased abundances of not only the causative bacterium Dichelobacter nodosus but also other species such as Mycoplasma fermentans and Porphyromonas asaccharolytica. Host transcriptomics reveals the suppression of biological processes related to skin barrier function, vascular functions, and immunosurveillance in unhealthy interdigital skin, supported by histological findings that type I collagen (associated with scar tissue formation) is significantly increased in footrot-affected interdigital skin compared to outwardly healthy skin. Finally, we provide some interesting indications of host and pathogen interactions associated with virulence genes and the host spliceosome, which could lead to the identification of future therapeutic targets.
Assuntos
Bactérias/imunologia , Pododermatite Necrótica dos Ovinos/imunologia , Interações Hospedeiro-Patógeno/imunologia , Imunidade/imunologia , Ovinos/imunologia , Animais , Colágeno Tipo I/imunologia , Pododermatite Necrótica dos Ovinos/microbiologia , Ovinos/microbiologia , Doenças dos Ovinos/imunologia , Doenças dos Ovinos/microbiologia , Pele/imunologia , Pele/microbiologia , Transcriptoma/imunologia , Virulência/imunologiaRESUMO
Footrot is a contagious foot disease mainly affecting sheep. It is caused by the Gram-negative anaerobic bacterium Dichelobacter nodosus. Warm, wet environmental conditions favour development of footrot, and under perfect conditions, it takes just 2-3 weeks from infection to manifestation of clinical signs. Affected sheep show lameness of various degrees and often graze while resting on their carpi. Local clinical signs vary in severity and extent from interdigital inflammation (benign footrot) to underrunning of the complete horn shoe in advanced stages of virulent footrot. Laboratory diagnosis ideally involves collection of four-foot interdigital swab samples followed by competitive real time PCR, allowing for detection of the presence of D. nodosus and differentiation between benign and virulent strains. Laboratory-based diagnostics at the flock level based on risk-based sampling and pooling of interdigital swab samples are recommended. The list of treatment options of individual sheep includes careful removal of the loose undermined horn, local or systemic administration of antimicrobials, systemic administration of non-steroidal anti-inflammatories (NSAIDs) and disinfectant footbathing. Strategies for control at the flock level are manifold and depend on the environmental conditions and the procedures traditionally implemented by the respective country. Generally, measures consist of treatment/culling of infected sheep, vaccination and prevention of reinfection of disease-free flocks. Gaining deeper insight into the beneficial effects of NSAIDs, screening for eco-friendly footbath solutions, developing better vaccines, including the development of a robust, reproducible infection model and elucidation of protective immune responses, as well as the elaboration of effective awareness training programs for sheep farmers, are relevant research gaps.
Assuntos
Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos/microbiologia , Doenças dos Ovinos/microbiologia , Abate de Animais , Animais , Anti-Infecciosos/uso terapêutico , Anti-Inflamatórios não Esteroides/uso terapêutico , Desinfetantes/administração & dosagem , Fazendeiros/educação , Pododermatite Necrótica dos Ovinos/prevenção & controle , Pododermatite Necrótica dos Ovinos/terapia , Coxeadura Animal/microbiologia , Ovinos , Doenças dos Ovinos/prevenção & controle , Doenças dos Ovinos/terapia , Irrigação Terapêutica , Vacinação/veterináriaRESUMO
Footrot is a worldwide economically important, debilitating disease caused by Dichelobacter nodosus. In sheep (Ovis aries), it is characterized by lesions of varying severity, depending on the strain, whereas Alpine ibex (Capra ibex) seem to develop severe lesions, whatever the strain. Healthy carriers occur in livestock but are rare in wild ruminants. Using a triangulation approach (retrospective questionnaire survey, necropsy database screening, and pathogen prevalence estimation in selected ibex colonies with and without footrot), we aimed at evaluating the importance of footrot in the ibex population, identifying potential risk factors for disease occurrence in this species, and defining the epidemiological role of ibex. Our study revealed that footrot occurs throughout the entire ibex territory (34% of the Swiss ibex colonies affected) but only as a sporadic disease (mostly one case per disease event), although the situation differed among footrot-positive colonies because half of them had experienced outbreak recurrences. Risk factor analysis for the occurrence of footrot in ibex colonies suggested an absence of an effect of meteorologic conditions, region, contacts with sheep or cattle (known to be very common healthy carriers of D. nodosus) and existing local disease control program. We found a significant effect only of contacts with sheep having footrot. Pathogen prevalence was very low in all investigated colonies. In conclusion, our results support previous data suggesting that ibex are susceptible spillover hosts, likely infected mainly by sympatric sheep displaying clinical signs.
Assuntos
Dichelobacter nodosus , Pododermatite Necrótica dos Ovinos/microbiologia , Doenças das Cabras/epidemiologia , Infecções por Bactérias Gram-Negativas/veterinária , Animais , Animais Selvagens , Pododermatite Necrótica dos Ovinos/epidemiologia , Cabras , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Suíça/epidemiologiaRESUMO
We present the largest and most representative study of the serological diversity of Dichelobacter nodosus in England. D. nodosus causes footrot and is one of the top five globally important diseases of sheep. The commercial vaccine, containing nine serogroups, has low efficacy compared with bivalent vaccines. Our aim was to investigate the prevalence and distribution of serogroups of D. nodosus in England to elucidate whether a bivalent vaccine could protect the national flock. Farmers from 164 flocks submitted eight interdigital swabs from eight, preferably diseased, sheep. All serogroups, A-I, were detected by PCR in 687/1150 D. nodosus positive swabs, with a prevalence of 2.6-69.3% of positive swabs per serogroup. There was a median of two serogroups per flock (range 0-6). Serogroups were randomly distributed between, but clustered within, flocks, with 50 combinations of serogroups across flocks. H and B were the most prevalent serogroups, present in > 60% of flocks separately but in only 27% flocks together. Consequently, a bivalent vaccine targeting these two serogroups would protect 27% of flocks fully (if only H and B present) and partially, if more serogroups were present in the flock. We conclude that one bivalent vaccine would not protect the national flock against footrot and, with 50 combinations of serogroups in flocks, flock-specific vaccines are necessary.
Assuntos
Dichelobacter nodosus/genética , Pododermatite Necrótica dos Ovinos/microbiologia , Sorogrupo , Doenças dos Ovinos/microbiologia , Animais , Inglaterra/epidemiologia , Feminino , Pododermatite Necrótica dos Ovinos/epidemiologia , Reação em Cadeia da Polimerase/veterinária , Sorotipagem/veterinária , Ovinos/microbiologia , Doenças dos Ovinos/epidemiologiaRESUMO
BACKGROUND: Footrot and interdigital dermatitis are endemic infectious diseases in all sheep farming regions, impairing welfare and production. The development of efficacious vaccines against the primary causative pathogen has been hampered by the extensive antigenic diversity of Dichelobacter nodosus. Understanding the heterogeneity of the pathogen within and between flocks is essential if the feasibility of bespoke vaccine production is to be assessed for use in the U.K. RESULTS: In this study 56 ewe and lamb isolates from 9 flocks were compared by D. nodosus serogroup and Multi Locus Sequence Type which provides significantly enhanced discriminatory power for molecular epidemiology. Serogroup heterogeneity between flocks ranged from two to five unique serogroups per flock. Three flocks contained isolates of two serogroups, two flocks contained isolates of three serogroups and one flock included isolates of five serogroups. Analysis of 25 isolates from one flock with high prevalence of lameness, identified that serogroup and sequence type was significantly correlated with age. Significantly higher proportion of lambs were infected with serogroup B (principally ST85) as opposed to serogroup H (principally ST86), which predominated amongst adult sheep. CONCLUSIONS: Genomic heterogeneity of the pathogen was significantly lower within flock compared to heterogenicity observed between flocks. Furthermore, this study indicates that within a flock, the host-pathogen dynamics and susceptibility to particular D. nodosus strains may be age dependent.
Assuntos
Dichelobacter nodosus/classificação , Heterogeneidade Genética , Infecções por Bactérias Gram-Negativas/veterinária , Tipagem de Sequências Multilocus/métodos , Doenças dos Ovinos/microbiologia , Animais , Técnicas de Tipagem Bacteriana , Dichelobacter nodosus/genética , Dichelobacter nodosus/isolamento & purificação , Dermatite Digital/microbiologia , Feminino , Pododermatite Necrótica dos Ovinos/microbiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Filogenia , Sorogrupo , Ovinos , Reino UnidoRESUMO
BACKGROUND: Ovine footrot caused by Dichelobacter nodosus (D nodosus) is an infectious disease affecting sheep worldwide. Switzerland plans a nationwide footrot eradication program, based on PCR-testing of interdigital swab samples. The aim of this study was to test for the presence of D nodosus in clinically footrot-free sheep flocks which had been subjected to different treatment strategies, to assess whether they were feasible for the eradication process, especially focussing on antimicrobial flock treatments. Clinical scoring and PCR-results were compared. Ten farms had used hoof bathing and hoof trimming without causing bleeding, ten had used individual treatments and flock vaccines to gain the free status and ten had become free through whole-flock systemic macrolide treatment. For every farm, three risk-based collected pool samples were analysed for the occurrence of virulent and benign D nodosus by PCR detection of aprV2/aprB2. RESULTS: Six flocks from any treatment group tested positive for aprB2 in all pools. Clinical signs were absent at the time of sampling, but some flocks had experienced non-progressive interdigital inflammation previously. Two flocks tested aprV2-positive in the high-risk pool. One of them underwent a progressive footrot outbreak shortly after sampling. Individual retesting indicated, that virulent D nodosus most likely was reintroduced by a recently purchased ram. In the second flock, a ram was tested positive and treated before clinical signs occurred. CONCLUSIONS: All treatment strategies eliminated the causative agent and were found to be suitable for implementation in the PCR-based eradication process. PCR-testing proved to be more sensitive than visual scoring, as it also detected clinically healthy carriers. It will be of benefit as a diagnostic tool in elimination and surveillance programs.
Assuntos
Dichelobacter nodosus/isolamento & purificação , Pododermatite Necrótica dos Ovinos/prevenção & controle , Infecções por Bactérias Gram-Negativas/veterinária , Doenças dos Ovinos/prevenção & controle , Criação de Animais Domésticos/métodos , Animais , Dichelobacter nodosus/efeitos dos fármacos , Dichelobacter nodosus/patogenicidade , Desinfetantes/uso terapêutico , Feminino , Pododermatite Necrótica dos Ovinos/tratamento farmacológico , Pododermatite Necrótica dos Ovinos/microbiologia , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/prevenção & controle , Casco e Garras/microbiologia , Macrolídeos , Masculino , Prevalência , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Ovinos , Doenças dos Ovinos/diagnóstico , Suíça , Vacinação/veterináriaRESUMO
Footrot is a contagious foot disease caused by the bacterium Dichelobacter nodosus (D. nodosus) that affects sheep worldwide. Due to substantial economic and welfare impact, various countries have developed control programs against footrot. The aim of this cross-sectional study was to estimate the national prevalence of virulent and benign D. nodosus in Switzerland in the four domestic ruminant species sheep, cattle, goats and South American camelids (SAC) to detect potential host populations and to propose targeted disease control measures. Risk factors for infection with the virulent strain of D. nodosus, based on a survey carried out among farmers, were investigated on animal and herd level. Overall, 613 farms and 2920 animals were investigated during 2017-18 applying a two-stage cluster sampling strategy. A Real-Time PCR method for simultaneous detection of virulent and benign strains of D. nodosus was used for the first time in such a large study. On animal level, the true prevalence (TP) of virulent D. nodosus in sheep was estimated at 16.9% (95% confidence interval (CI95%): 9.5-24.3%). In cattle and goats no virulent D. nodosus was detected and in SAC an apparent prevalence (AP) of 0.2% (CI95%: 0.0-0.4%) was observed. On farm level, a TP of virulent D. nodosus of 16.2% (CI95%: 8.4-25.2%) for sheep and an AP of 1.5% (CI95%: 0.3-5.2%) for SAC herds was estimated. Since the Swiss control program only targets the virulent strains of D. nodosus, it was concluded that cattle, goats and SAC do not play a role in footrot epidemiology in Switzerland. Adult sheep were at higher risk of infection for virulent D. nodosus compared to lambs and yearlings. On herd level, risk factors for infection with virulent D. nodosus in sheep were earlier occurence of footrot, winter compared to summer and autumn, and goat contact on pasture. Liming pastures had a protective effect on D. nodosus infection. For benign D. nodosus, the TP in sheep was 6.3% (CI95%: 1.6-11.0%) and in cattle 88.4% (CI95%: 83.8-93.0%). The TP for benign D. nodosus in sheep farms was 2.8% (CI95%: 0.0-10.5%) and in cattle farms 95.9% (CI95%: 91.7-98.1%). In goat and SAC farms, the AP was 6.6% (CI95%: 3.4-11.5%) and 7.4% (CI95%: 3.8-13.1%), respectively. These findings could be relevant for wild ruminants such as Alpine ibex (Capra ibex ibex), which can develop clinical footrot after infection with benign D. nodosus. The findings of this study are crucial for assessing targeted disease control measures in Switzerland.
Assuntos
Camelídeos Americanos , Doenças dos Bovinos/epidemiologia , Dichelobacter nodosus/isolamento & purificação , Pododermatite Necrótica dos Ovinos/epidemiologia , Doenças das Cabras/epidemiologia , Infecções por Bactérias Gram-Negativas/veterinária , Doenças dos Ovinos/epidemiologia , Animais , Bovinos , Doenças dos Bovinos/microbiologia , Doenças dos Bovinos/prevenção & controle , Estudos Transversais , Feminino , Pododermatite Necrótica dos Ovinos/microbiologia , Pododermatite Necrótica dos Ovinos/prevenção & controle , Doenças das Cabras/microbiologia , Doenças das Cabras/prevenção & controle , Cabras , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/prevenção & controle , Masculino , Prevalência , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Ovinos , Doenças dos Ovinos/microbiologia , Doenças dos Ovinos/prevenção & controle , Carneiro Doméstico , Suíça/epidemiologiaRESUMO
Sites of persistence of bacterial pathogens contribute to disease dynamics of bacterial diseases. Footrot is a globally important bacterial disease that reduces health and productivity of sheep. It is caused by Dichelobacter nodosus, a pathogen apparently highly specialised for feet, while Fusobacterium necrophorum, a secondary pathogen in footrot is reportedly ubiquitous on pasture. Two prospective longitudinal studies were conducted to investigate the persistence of D. nodosus and F. necrophorum in sheep feet, mouths and faeces, and in soil. Molecular tools were used to detect species, strains and communities. In contrast to the existing paradigm, F. necrophorum persisted on footrot diseased feet, and in mouths and faeces; different strains were detected in feet and mouths. D. nodosus persisted in soil and on diseased, but not healthy, feet; similar strains were detected on both healthy and diseased feet of diseased sheep. We conclude that D. nodosus and F. necrophorum depend on sheep for persistence but use different strategies to persist and spread between sheep within and between flocks. Elimination of F. necrophorum would be challenging due to faecal shedding. In contrast D. nodosus could be eliminated if all footrot-affected sheep were removed and fade out of D. nodosus occurred in the environment before re-infection of a foot.
Assuntos
Infecções Bacterianas/microbiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Doenças dos Ovinos/microbiologia , Animais , Infecções Bacterianas/patologia , Infecções Bacterianas/veterinária , Dichelobacter nodosus/patogenicidade , Pododermatite Necrótica dos Ovinos/patologia , Infecções por Fusobacterium/microbiologia , Infecções por Fusobacterium/patologia , Infecções por Fusobacterium/veterinária , Fusobacterium necrophorum/patogenicidade , Casco e Garras/microbiologia , Casco e Garras/patologia , Ovinos/genética , Ovinos/microbiologia , Doenças dos Ovinos/patologia , Virulência/genéticaRESUMO
OBJECTIVE: Dichelobacter nodosus is the primary aetiological agent of footrot in sheep. Ovine footrot causes considerable economic losses and substantial animal welfare issues in the Australian sheep industry. Current methods for detecting D. nodosus are difficult, laborious and time-consuming. Recently, we developed a robust LAMP assay (VDN LAMP) that was able to identify aprV2 positive D. nodosus in-field. A major advantage of LAMP technology is the ability of the assay to be performed by non-specialists with minimal training. We aimed to assess the performance of the VDN LAMP in-field in comparison to a laboratory-based aprV2/aprB2 rtPCR when used by secondary users after training by the authors. RESULTS: Two animal health officers (termed secondary users) from Department of Primary Industries and Regions, South Australia (PIRSA) were trained in the use of VDN LAMP, before carrying out in-field testing on several locations in South Australia. The performance of VDN LAMP assay by secondary user 1 was shown to successfully detect 73.91% (n = 53) aprV2 positive samples, while secondary user 2 detected 37.93% (n = 30) aprV2 positive samples. Overall, the ability to identify virulent D. nodosus by VDN LAMP by secondary users was mixed for various reasons, however, this could be rectified by additional training and commercial production of the LAMP kits to increase stability. We envisaged in the future VDN LAMP will able to be used by non-specialists to aid control programs.
Assuntos
Técnicos em Manejo de Animais/estatística & dados numéricos , Proteínas de Bactérias/genética , Dichelobacter nodosus/genética , Pododermatite Necrótica dos Ovinos/diagnóstico , Infecções por Bactérias Gram-Negativas/veterinária , Técnicas de Amplificação de Ácido Nucleico/métodos , Serina Endopeptidases/genética , Doenças dos Ovinos/diagnóstico , Técnicos em Manejo de Animais/normas , Animais , Dichelobacter nodosus/fisiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/microbiologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Ovinos , Doenças dos Ovinos/microbiologia , Austrália do SulRESUMO
INTRODUCTION: Ovine footrot caused by Dichelobacter nodosus is a highly contagious and painful disease representing an economic as well as an animal welfare problem. In order to get more information on the infection dynamics, 26 lambs and 4 ewes enrolled in an in-contact infection trial were monitored over two weeks for the presence of D. nodosus-specific DNA. Two D. nodosus-positive ewes were housed together with 13 confirmed negative lambs. The control group consisted of another 13 lamb siblings and two confirmed D. nodosus-negative ewes. Every foot of all sheep was sampled seven times over the two weeks experiment period and subsequently analyzed for the presence of D. nodosus by quantitative real-time PCR. The control group was negative at the beginning and the end of the experiment and showed no clinical symptoms of footrot. The two positive ewes showed a high, but hundred fold differing level of virulent D. nodosus that remained constant over time with one of the ewes being also weakly positive for benign D. nodosus. All lambs of the infection group were positive for virulent D. nodosus at 14 days post infection (dpi). The first positive animals were observed on 3 dpi. The D. nodosus load remained at a low level and only increased in a few lambs at the end of the trial. Five of the contact lambs showed suspicious clincal signs (score 1-2) at 14 dpi corroborating the PCR results and indicating that the disease starts as early as two weeks after contact with positive sheep.
INTRODUCTION: Le piétin causé par Dichelobacter nodosus est une maladie hautement contagieuse et douloureuse qui représente à la fois un problème économique et de bien-être animal. Pour avoir plus informations sur la dynamique de l'infection, 26 agneaux et 4 brebis appartenant à un groupe d'essai d'infection par contact ont été contrôlés pendant deux semaines quant à la présence d'ADN spécifique de D. nodosus. Deux brebis positives pour D. nodosus ont été mises en contact avec 13 agneaux confirmés négatifs. Le groupe témoin était formé de 13 autres agneaux et deux brebis confirmées négatives. Sept échantillons sur écouvillon ont été prélevés sur chaque pied de chaque mouton au cours des deux semaines de la période expérimentale et analysés quant à la présence de D. nodosus par PCR quantitative en temps réel. Le groupe témoin était négatif au début et à la fin de l'expérience et n'a montré aucun symptôme clinique de piétin. Les deux brebis positives ont montré une forte présence de D. nodosus virulent, mais de cent niveaux différents, qui est restée constant dans le temps, l'une des brebis étant aussi faiblement positive pour D. nodosus bénin. Tous les agneaux du groupe infecté étaient positifs pour D. nodosus virulent 14 jours après l'infection (dpi). Les premiers animaux positifs ont été observés à 3 dpi. La charge de D. nodosus est restée faible et n'a augmenté que chez quelques agneaux à la fin de l'expérience. Cinq des agneaux en contact ont présenté des symptômes suspects (score 1-2) à 14 dpi, corroborant les résultats de la PCR et indiquant que l'infection commence dès deux semaines après le contact avec des moutons positifs.
Assuntos
Infecções por Bactérias Gram-Negativas/veterinária , Animais , Carga Bacteriana , Dichelobacter nodosus/fisiologia , Feminino , Pododermatite Necrótica dos Ovinos/diagnóstico , Pododermatite Necrótica dos Ovinos/epidemiologia , Pododermatite Necrótica dos Ovinos/microbiologia , Pododermatite Necrótica dos Ovinos/transmissão , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/transmissão , Reação em Cadeia da Polimerase , Ovinos , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/microbiologia , Doenças dos Ovinos/transmissão , Suíça/epidemiologiaRESUMO
Fusobacterium necrophorum is a Gram negative, rod-shaped and aero tolerant anaerobe. In animals, it is an opportunistic pathogen frequently associated with necrotic infections, generally called necrobacillosis, such as calf diphtheria, foot rot and liver abscesses in cattle. Two subspecies exist: subsp. necrophorum and subsp. funduliforme. Among several virulence factors, leukotoxin (Lkt) is considered to be a major factor and a protective antigen. The objective of the study was to utilize BL3 cells and measure the release of lactic dehydrogenase to quantify Lkt activity of F. necrophorum. The assay was used to examine the effects of storage and handling conditions, growth media, polymyxin B addition on the cytotoxicity and evaluate Lkt activities of F. necrophorum strains isolated from bovine liver abscesses and foot rot. The Lkt activity peaked at 9â¯h of incubation. There was a significant decrease in the cytotoxicity measured in the samples after each freeze and thaw cycle. No difference was observed in the cytotoxicity for the samples handled aerobically versus anaerobically. Lkt activities of strains grown in anaerobic Brain-Heart Infusion broth were higher compared to Vegitone broth. A small reduction in the cytotoxicity activity was observed after the addition of polymyxin. The Lkt activity was consistently higher in strains of subsp. necrophorum than subsp. funduliforme of liver abscess origin. Among the strains isolated from cattle foot rot, Lkt activities of subsp. necrophorum strains appear to be much more variable. Use of BL3 cells in combination of lactic acid dehydrogenase assay appears to be a simple and valid assay to measure Lkt activity of F. necrophorum.