Future Breakdown Research Articles

Molecular tools for the diagnosis of periodontitis

Periodontitis is a multifactorial chronic inflammatory disease associated with dysbiotic biofilms and aberrant host inflammatory response. It is characterized by destruction of the tissues that support the teeth. Periodontitis is the major cause of tooth loss in adults significantly affecting the quality of life and is associated with many chronic non communicable diseases by contributing to systemic inflammatory burden. Early and accurate diagnosis is the key to the successful management of periodontitis as the entire treatment plan, prognosis, and maintenance directly depend on the quality of periodontal diagnosis. Traditionally the diagnosis of Periodontitis is based on recording medical and dental history, periodontal examination and radiographic findings. The current periodontal diagnostic process reveals only historical tissue destruction and does not provide any information regarding current disease activity, future progression or for monitoring response to therapy. For these reasons, new molecular diagnostic aids are being developed that allow an early detection of disease, determine the presence of current disease activity, predict sites at risk for future breakdown and monitor the response to periodontal therapy. Advanced molecular diagnostic techniques are a class of diagnostic tests that are used to detect and measure nucleic acids, proteins or metabolites in clinical samples to identify risk factors, screen asymptomatic patients, provide more accurate diagnosis and guide the process of development of an ideal therapeutic intervention. This paper provides a review of the molecular diagnostic tools that have the potential to be utilized for diagnosis and management of periodontitis.

Origin of MMP-8 and Lactoferrin levels from gingival crevicular fluid, salivary glands and whole saliva

BackgroundPathologically elevated levels of matrix metalloproteinase-8 (MMP-8) and Lactoferrin in oral fluids have been associated with the presence of gingivitis/periodontitis. This study aimed to assess the origin of MMP-8 and Lactoferrin in periodontitis patients and to identify the degree to which conventional clinical parameters correlate with their presence.MethodsA total of ten periodontitis and ten healthy patients were included in this study. Whole saliva (stimulated and unstimulated), parotid/sublingual glandular fluid and gingival crevicular fluid from pockets and sulci were tested for MMP-8 and Lactoferrin and protein concentrations were quantified using an ELISA assay. Clinical parameters were checked for potential associations with MMP-8 and Lactoferrin levels.ResultsPeriodontal patients presented higher concentrations of MMP-8 and Lactoferrin in pockets than other sources (P = 0.03). Lactoferrin measurement was higher in the parotid compared to sublingual glandular fluid in periodontitis patients (P = 0.03). Increased probing pocket depth was positively correlated with high MMP-8 and Lactoferrin levels.ConclusionsPeriodontal pockets appear to be the major source of active matrix metalloproteinase and Lactoferrin, which also may also enter the oral cavity through the salivary glands. Since clinically healthy sites in periodontitis patients also had elevated biomarker levels, gingival crevicular fluid biomarker testing may be more predictive of future tissue breakdown than conventional clinical parameters.

Future Risk of Bovine Tuberculosis (Mycobacterium bovis) Breakdown in Cattle Herds 2013-2018: A Dominance Analysis Approach.

Bovine tuberculosis (bTB) remains a significant endemic pathogen of cattle herds, despite multi-decadal control programmes being in place in several countries. Understanding the risks of future bTB breakdown (BD) and the associated characteristics of herds and index breakdowns could help inform risk categorisation. Such risk categories could then contribute to tailored management and policies. Here, we estimated the future risk of herd BD for the cohort of herds that were derestricted during 2013 in Ireland using multivariable logit regression models, with a dominance analysis approach. One third of herds that were derestricted in 2013 experienced a breakdown during the follow-up five year period (1469/4459; 33%). BD length was a significant predictor of future risk, primarily driven by long BDs > 230 days relative to short BDs < 130 days (OR 95%CI: 1.157–1.851), as was having had a previous BD (OR 95%CI: 1.012–1.366). Herd-size was the dominant predictor of future risk (accounted for 46% of predicted variance), suggesting significant increase in risk of future breakdown with increasing (log) herd-size (OR 95%CI: 1.378–1.609). There was significant spatial variation in future risk across counties, and it was the second most dominant predictor of future risk (25% of predicted variance). The size of index breakdowns was not a strong predictor of future risk over a 5-year period. These findings can inform a risk-based policy development.

Intelligent machine learning based total productive maintenance approach for achieving zero downtime in industrial machinery

The unpredicted breakdowns in any industrial plant paves way for huge loss to the industry in terms of production and profit. If near future breakdowns are known well ahead of time, zero downtime can be achieved, maintaining the demand–supply chain which leads to industry-4.0 standard. This paper addresses the challenges involved in such transformation and proposes a monitoring and control procedure to reduce catastrophic breakdown by 84%. The parameters and signatures related to the breakdown phenomenon which are restricting zero down time in industry-3.0 are analysed. Adaptive ARIMA model based machine learning to support adaptive error prediction model through varying windowing technique is proposed to predict the future breakdown before its occurrence by forecasting the important signature parameters in the machinery. The proposed maintenance approach is implemented in a high-pressure hydraulic sand moulding machine in an automotive grey casting manufacturing foundry. In this work, the oil contamination level is the parameter identified for analysis in the high pressure sand moulding line in foundry. The breakdown in minutes per month and the number of breakdown occurrences in a month due to various phenomena are analysed after implementing the proposed approach. The proposed system ensures promising results which increases Mean Time Between-Failure by 800% and thereby achieving zero downtime in industries.

Evaluation of Gingival Crevicular Fluid and Serum Tartrate-resistant Acid Phosphatase Levels in Subjects with Clinically Healthy Periodontium and Chronic Periodontitis - A Clinico-biochemical Study.

Background:Periodontitis is a chronic inflammatory disease with conglomerate etiology making it difficult to diagnose at the early stages. Potential biomarkers in gingival crevicular fluid (GCF) would determine the presence of the current disease activity, predict sites vulnerable for future breakdown, and assess the response to periodontal interventions. Merely elevated levels of inflammatory soft-tissue markers do not indicate bone destruction. Since there is no single ideal biomarker established, bone-related biomarkers such as telopeptide of type I collagen, osteocalcin, calprotectin, osteopontin, and tartrate-resistant acid phosphatase (TRAP) seem to hold great promise as predictive markers to determine bone destruction and active phases in the disease progression. The present study is intended to explore the biologic plausibility of the levels of TRAP in health and chronic periodontitis.Materials and Methods:The present cross-sectional clinico-biochemical study comprised 30 systemically healthy subjects with 15 periodontally healthy and 15 chronic periodontitis subjects who were age and gender matched. GCF and blood samples were collected from all the patients. TRAP estimation was done in both the samples using an enzyme-linked immunosorbent assay kit. The data were analyzed using independent t-test and Pearson correlation test.Results:Serum and GCF TRAP levels in chronic periodontitis subjects were significantly higher when compared to the periodontally healthy group. There were no significant correlations found among serum and GCF TRAP levels with increasing age and gender in both the groups. An increase in disease severity, i.e., increase in probing pocket depth and clinical attachment level, did not show correlation with the GCF and serum TRAP levels in the chronic periodontitis group.Conclusion:Based on the findings of the present study, increased GCF TRAP levels in chronic periodontitis seem to be a potential marker for identifying ongoing periodontal destruction.

Gingival Crevicular Fluid Cytokines in Moderate and Deep Sites of Stage III Periodontitis Patients in Different Rates of Clinical Progression.

Clinical criteria are inappropriate to measure the degree of susceptibility to progression of periodontal damage. Thus, the aim of this study was to assess whether gingival crevicular fluid (GCF) levels of cytokines could discriminate patients suffering from stage III periodontitis with moderate (Grade B) and rapid rates of progression (Grade C) prior to and 6 months after non-surgical periodontal treatment. GCF samples were obtained from moderate and deep sites of 20 patients diagnosed as Grade B and 20 patients as grade C stage III periodontitis and analyzed for interleukin (IL)-1β, IL-9, tumor necrosis factor (TNF)-α, and vascular endothelial growth factor (VEGF) using a high-sensitivity Bio-Plex Suspension Array System. At baseline, higher IL-1β but lower IL-9 GCF levels were observed in moderate sites of the grade C compared to the grade B group. In spite of comparable clinical improvement, this difference maintained after treatment, suggesting a residual pro-inflammatory state. In deep sites, no differences were observed between periodontitis groups except for VEGF levels that decreased more in Grade B periodontitis at 6 months post-therapy. A mathematical model was constructed to identify Grade C periodontitis patients based on the subjects’ GCF levels of IL-1β and IL-9, which achieved an area under the receiver-operating characteristic (ROC) curve of 0.94. This study can contribute to the early assessment of risk of future breakdown in periodontitis patients.

Wavelength dependence of nanosecond infrared laser-induced breakdown in water: Evidence for multiphoton initiation via an intermediate state

Abstract : Investigation of the wavelength dependence (725 1025 nm) of the threshold for nanosecond optical breakdown in water revealed steps consistent with breakdown initiation by multiphoton ionization, with an initiation energy of about 6.6 eV. This value is considerably smaller than the autoionization threshold of about 9.5 eV, which can be regarded as band gap relevant for avalanche ionization. Breakdown initiation is likely to occur via excitation of a valence band electron into a solvated state, followed by rapid excitation into the conduction band. Theoretical analysis based on these assumptions suggests that the seed electron density required for initiating avalanche ionization drops from 2.51015 cm-3 at 725 nm to 1.11012 cm-3 at 1025 nm. These results demand changes of future breakdown modeling for water including the use of a larger band gap than previously employed, the introduction of an intermediate energy level for initiation, and consideration of the wavelength dependence of seed electron density.

철강회사에서 기계 고장 진단 사례연구

Rotating equipment seldom fails without notice, so breakdowns can usually be predicted and avoided by watching for signs of failure. In this paper, We study case for rotary machine with a breakdown analysis. Also We analyze the solution of the safety and the future breakdown of the each rotary machine through vibration analysis using measurement data. The implementation of the measurement and the test results are discussed. The result with suggested method showed netter stable Condition Monitoring & Diagnostics.

Bovine tuberculosis in Northern Ireland: Risk factors associated with time from post-outbreak test to subsequent herd breakdown

Compulsory bovine tuberculosis testing has been implemented since 1959 in Northern Ireland. Initial rapid progress in the eradication of the disease was followed by a situation where disease levels tended to fluctuate around a low level. This study explores recrudescence of bovine tuberculosis (bTB) in Northern Ireland herds by assessing risk factors associated with time from the six-month post-outbreak skin test until a further herd breakdown. Bovine herds (n=3377) were recruited in 2002 and 2003 and their survival analysed using Kaplan–Meier survival estimates and a Cox proportional hazards model, with follow-up extending to August 2008. Exclusion criteria applied for study entry were bTB infection in a contiguous herd, changing of post restriction test to one of a higher risk status or chronic infection. Chronic infection was defined as any situation where disclosure preceded the post-outbreak test by two years or more. The application of these exclusion criteria meant that herds recruited to the study were largely cleared of infection and not directly contiguous to other infected herds. Of the 3377 herds, 1402 (41.5%) suffered a further herd breakdown before the end of follow-up. Median survival time was 582 days (interquartile range=336–1002 days). Breakdown severity (defined as the number of Single Intradermal Comparative Tuberculin Test (SICTT) reactors at disclosure test), local bTB prevalence, herd size and type were identified as significant risk factors (p<0.05), as was the purchase of higher numbers (n>27.38 per year) of cattle. Consistent with other studies this work shows bTB confirmation to not be predictive of a future herd breakdown. This work shows bTB history as not being a risk factor for a future breakdown. This result could be reflective of the exclusion criteria used in the study, which may have selected for incidents where historical status was of less importance.

Shadow Banking: Policy Challenges for Central Banks

Central banks responded with exceptional liquidity support during the financial crisis to prevent a systemic meltdown. They broadened their tool kit and extended liquidity support to nonbanks and key financial markets. Many want central banks to embrace this expanded role as “market maker of last resort” going forward. This would provide a liquidity backstop for systemically important markets and the shadow banking system that is deeply integrated with these markets. But how much liquidity support can central banks provide to the shadow banking system without risking their balance sheets? I discuss the expanding role of the shadow banking sector and the key drivers behind its growing importance. There are close parallels between the growth of shadow banking before the recent financial crisis and earlier financial crises, with rapid growth in near monies as a common feature. This ebb and flow of shadow-banking-type liabilities are indeed an ingrained part of our advanced financial system. We need to reflect and consider whether official sector liquidity should be mobilized to stem a future breakdown in private shadow banking markets. Central banks should be especially concerned about providing liquidity support to financial markets without any form of structural reform. It would indeed be ironic if central banks were to declare victory in the fight against too-big-to-fail institutions, just to end up bankrolling too-big-to-fail financial markets.

Periodontium biotype modification prior to an orthodontic therapy: Case report

IntroductionThin periodontium is frequently characterized by osseous defects and dehiscence; moreover, it exhibits pathological changes like gingival recession when subjected to traumatic surgical insults or orthodontic force more than thick periodontium. Therefore, this case report aimed to validate the need for bio-modification of thin periodontium before an orthodontic treatment. Case descriptionA 30-year old female patient who had started on orthodontic treatment which was not completed because of hypermobility of the anterior teeth. Periodontal diagnosis revealed a localized chronic slight periodontitis and severe crowding in the anterior mandibular arch and ridge defects (Siebert class I) at the sites of missing maxillary lateral incisors. The patient was prepared for periodontal surgery by scaling and root planning. Periodontal surgery included frenectomy and simultaneous bone augmentation using GBR procedure which was done using 0.5mg of BioOss® and 20×30mm size/GBR membrane (AlloDerm®) then 625mg Augmentin® TID and 400 Ibuprofen® TID, were prescribed for 7days. ResultsThe patient responded well to the surgical treatment and neither bleeding pockets nor probing depth exceeding 4mm was detected at the follow-up examinations. The mobility of Teeth #11 and #21 reduced from grade II to almost normal status. The soft tissues were well adapted and the defects in the sites of the missing maxillary lateral incisors disappeared. One year later the orthodontic therapy was restarted. ConclusionsThe outcomes of this case treatment showed that the thickening of the soft tissues, before an orthodontic treatment has a clinical positive effect. Moreover; transferring the case from thin periodontium to thick periodontium would have reduced the possibility of future breakdown of the periodontium during the orthodontic therapy.

Comparison of bovine tuberculosis recurrence in Irish herds between 1998 and 2008

During the last several decades in Ireland, there has been substantial scientific progress in our understanding and related policy changes in the bovine tuberculosis (bTB) eradication programme. A range of performance measurements are routinely available, each highlighting a steadily improving situation in Ireland. However, recent research has highlighted an on-going problem of residual infection, contributing to recurrent breakdowns. In light of this general improvement, but also cognisant of residual infection, a critical evaluation of changes in effectiveness of managing recurrence is particularly valuable. Therefore, the objective of the study was to compare the herd-level risk of recurrence of bTB in Ireland between 1998 and 2008. A retrospective cohort study was carried out, using a Cox proportional-hazards model, to compare the risk of restriction recurrence in herds derestricted during 1998 and 2008. These herds were observed for up to 3 years from the end of the ‘index restriction’. At the univariable level, 46.4% and 34.8% of study herds derestricted in 1998 and 2008, respectively, had a subsequent breakdown during the study period (χ2=70.6, P<0.001). In the multivariable analysis, there has been a significant reduction in bTB recurrence in Ireland, with 2008-derestricted herds being 0.74 times (95% confidence interval: 0.68–0.81) as likely to be restricted during the subsequent study period compared with 1998-derestricted herds. In the final Cox model, the rate of a future breakdown increased with increasing herd size, increasing number of standard reactors in the index restriction, increasing percentage of newly restricted herds within the District Electoral Division (DED) and if the herd had a previous bTB episode in the previous 5 years. The risk varied across herd type. The results from the current study provide further reassurance of an improved national situation, both in terms of limiting the establishment of new infection (bTB incidence) and in effectively clearing infection once detected (recurrence following derestriction). Recurrence of bTB requires effective implementation of multiple control strategies, focusing on identifying and removing residually infected cattle, and limiting environmental sources of infection, which in Ireland primarily relates to badgers.

The exponential eigenmodes of the carbon-climate system, and their implications for ratios of responses to forcings

Abstract. Several basic ratios of responses to forcings in the carbon-climate system are observed to be relatively steady. Examples include the CO2 airborne fraction (the fraction of the total anthropogenic CO2 emission flux that accumulates in the atmosphere) and the ratio T/QE of warming (T) to cumulative total CO2 emissions (QE). This paper explores the reason for such near-constancy in the past, and its likely limitations in future. The contemporary carbon-climate system is often approximated as a set of first-order linear systems, for example in response-function descriptions. All such linear systems have exponential eigenfunctions in time (an eigenfunction being one that, if applied to the system as a forcing, produces a response of the same shape). This implies that, if the carbon-climate system is idealised as a linear system (Lin) forced by exponentially growing CO2 emissions (Exp), then all ratios of responses to forcings are constant. Important cases are the CO2 airborne fraction (AF), the cumulative airborne fraction (CAF), other CO2 partition fractions and cumulative partition fractions into land and ocean stores, the CO2 sink uptake rate (kS, the combined land and ocean CO2 sink flux per unit excess atmospheric CO2), and the ratio T/QE. Further, the AF and the CAF are equal. Since the Lin and Exp idealisations apply approximately to the carbon-climate system over the past two centuries, the theory explains the observed near-constancy of the AF, CAF and T/QE in this period. A nonlinear carbon-climate model is used to explore how future breakdown of both the Lin and Exp idealisations will cause the AF, CAF and kS to depart significantly from constancy, in ways that depend on CO2 emissions scenarios. However, T/QE remains approximately constant in typical scenarios, because of compensating interactions between CO2 emissions trajectories, carbon-climate nonlinearities (in land–air and ocean–air carbon exchanges and CO2 radiative forcing), and emissions trajectories for non-CO2 gases. This theory establishes a basis for the widely assumed proportionality between T and QE, and identifies the limits of this relationship.

Utilization of a major brown rust resistance gene in sugarcane breeding

Brown rust, caused by Puccinia melano- cephala, has had devastating effects on sugarcane (Saccharum spp.) breeding programs and commercial production. The discovery of Bru1, a major gene conferring resistance to brown rust, represented a substantial breakthrough. Markers for Bru1 are the first available for sugarcane molecular breeding. The contribution of Bru1 towards brown rust resistance in the Canal Point (CP) sugarcane breeding program was determined as a means of directing future breeding strategies. Bru1 was detected in 285 of 1,072 (27 %) clones used for crossing; this germplasm represents the genetic base for cultivar development in Florida. The frequency of Bru1 was greatest in CP clones (42 %) and lowest among Louisiana clones (6 %). Bru1 was not detected in clones with year assignments before 1953. However, Bru1 frequency increased from 15 % (assignments 1975-1985) to 47 % in the current decade. The increase coincided with the introduction of brown rust to Florida. Bru1 was detected in 155 (32 %) of 485 parental clones tested for brown rust susceptibility at two field locations. Of clones classed resistant to brown rust, 154 (59 %) contained Bru1, yet none of 100 susceptible clones contained the gene. Bru1 was detected in 667 (44 %) clones in the second clonal stage of selection, 87 % of which were free of brown rust symptoms. Bru1 is the predominant source of resistance in the Florida sugarcane genetic base. Efforts to identify and integrate new brown rust resistance genes must be pursued to minimize risks associated with a future breakdown in major gene resistance provided by Bru1.

Joint Prediction of Continuous and Discrete States in Time-Series Based on Belief Functions

Forecasting the future states of a complex system is a complicated challenge that is encountered in many industrial applications covered in the community of prognostics and health management. Practically, states can be either continuous or discrete: Continuous states generally represent the value of a signal while discrete states generally depict functioning modes reflecting the current degradation. For each case, specific techniques exist. In this paper, we propose an approach based on case-based reasoning that jointly estimates the future values of the continuous signal and the future discrete modes. The main characteristics of the proposed approach are the following: 1) It relies on the K-nearest neighbor algorithm based on belief function theory; 2) belief functions allow the user to represent his/her partial knowledge concerning the possible states in the training data set, particularly concerning transitions between functioning modes which are imprecisely known; and 3) two distinct strategies are proposed for state prediction, and the fusion of both strategies is also considered. Two real data sets were used in order to assess the performance in estimating future breakdown of a real system.

The economics of evolution: Henry Ford and the Model T

For the past 30 years evolutionary biologists have used a fictional tale about engineer and businessman Henry Ford to help illustrate the undesirability of over-design. Thus, on discovering that kingpins were rarely damaged in scrapped Model T automobiles, Henry Ford is alleged to have concluded that the kingpins were unnecessarily durable and asked that they be built to a cheaper specification. The general lesson that has been drawn from this tale is that natural selection will act to equalize the mortality risks accruing from damage to each part of the organism's body. Yet it is well known, at least as far as humans are concerned, that death is more likely to be attributed to a failure of some organs compared to others. To understand why this might be so, we use some graphical and mathematical models to show that even if all body organs were equally important to survivorship, then the optimal investment solution that maximizes whole-organism longevity will typically not be the solution that equalizes the fail-times of the individual organs. As with natural organisms, the key to any optimal investment policy in multi-component systems is understanding what ‘bang you can get for your buck’. Moreover, we use a specific model to show that, even following selection to ameliorate the effects of damage, those body parts that receive more damage are still more likely to be the ultimate cause of death – that is, there is ‘under-compensation’. Therefore, the decision to make the kingpins more cheaply should not have been based only on the fact they rarely cause car failure compared to other car components. Such arguments wrongly assume that if one car part (or body part) is less durable than the others, then it will always be the reason for any future breakdown (or death).

Lessons from the past: managing insecticide resistance in malaria control and eradication programmes

The distribution of insecticide-treated bednets to help combat the burden of malaria in sub-Saharan Africa has accelerated in the past 5 years. Additionally, many countries are also considering, or have already begun, indoor residual spraying campaigns. These are positive developments, since vector control has repeatedly proven to be an effective means of reducing malaria transmission. However, the sustainability of these insecticide-based interventions relies on the continuing susceptibility of the anopheles vectors to the limited number of available insecticides. Continual monitoring for early signs of insecticide resistance and the adoption of carefully considered resistance management strategies are therefore required. Regrettably, this essential monitoring component is frequently given a low priority in the push to meet ambitious coverage targets. We outline the key requirements for establishing an insecticide resistance surveillance system and urge all those involved in malaria vector control, either directly or as facilitators, to ensure that these measures are incorporated into control programmes. Failure to act now will inevitably lead to a future breakdown in disease control and jeopardise hopes of eradicating this major public-health problem.

Stellite Failure on a P91 HP Valve — Failure Investigation and Modelling of Residual Stresses

The sequence of the primary welding process and the following secondary processes of machining, and heat treatment has been modelled to predict the residual conditions in a Stellite 6 overlay weld on a P91 steam turbine valve. The different process steps are coupled in order to transfer the residual conditions from preceding processes to the ones following. The integrated model has been used to analyse a premature rupture in the weld zone between P91 and Stellite. An accurate prediction of the stress level in the weld zone is imperative for the assessment of the quality of the component, and this provides a tool for process modification in order to minimize the risk for future breakdown. Both classical time independent and time dependent plasticity models have been used to describe the different material behaviours during the different process steps. The description of the materials is highly temperature dependent. The welding process is modelled by adding material to the calculation domain, while the machining process is modelled by removing material from the calculation domain to redistribute the stress fields. An in-house iso-parametric FEM-code is used for the implementation of the material models and the discretization of the appropriate addition and removal of material. The return mapping algorithm is used for the time discretization of the time independent plasticity model, and a Norton’s power law model is used for the time dependent model. Results from the numerical calculations are presented.

Breakdown severity during a bovine tuberculosis episode as a predictor of future herd breakdowns in Ireland

A retrospective cohort study of Irish cattle herds investigated whether the severity of a herd’s bovine tuberculosis (BTB) breakdown was a predictor of the hazard of a future BTB breakdown in that herd. Data on 10,926 herds not having had BTB in 1995 (the “non-exposed” group) were obtained using a 10% random sample from all herds without BTB in 1995. Data on 6757 herds that had a new BTB breakdown in 1995 (the “exposed” group) were obtained and categorized into five increasing exposure-severity classes based on the total number of standard reactors (to the single intra-dermal comparative cervical tuberculin test) detected during the breakdown. Exposed herds were deemed to be free of BTB after they passed a 6-month check test; non-exposed herds were deemed free as of the date of the first negative herd-test in 1995. In the 5 years after 1995, 18% of the non-exposed herds had a BTB breakdown, whereas 31% of the exposed herds had a subsequent breakdown. Relative to the hazard for non-exposed herds, the hazard for the first future singleton standard reactor breakdown, was 1.6-times higher for exposed herds with only 1 standard reactor in 1995, and 1.8-times higher for those exposed herds with 4–8 standard reactors during the 1995 episode. When the outcome for future breakdowns was 2 or more standard reactors, the hazard ratios ranged from 1.6 for exposed herds with only 1 standard reactor in 1995 up to 2.9 in exposed herds with 8 or more standard reactors during the 1995 episode. The latter hazard ratio varied over time, decreasing to 1.7 after 3 years of risk. The hazard of a future BTB breakdown increased directly with number of cattle in the herd, a positive history of previous BTB in the herd, and the local herd prevalence of BTB. The presence of confirmed BTB lesions in reactor cattle was not predictive of the future breakdown hazard when the effects of other factors were controlled.

Breakdown severity during a bovine tuberculosis episode as a predictor of future herd breakdowns in Ireland

A retrospective cohort study of Irish cattle herds investigated whether the severity of a herd’s bovine tuberculosis (BTB) breakdown was a predictor of the hazard of a future BTB breakdown in that herd. Data on 10,926 herds not having had BTB in 1995 (the “non-exposed” group) were obtained using a 10% random sample from all herds without BTB in 1995. Data on 6757 herds that had a new BTB breakdown in 1995 (the “exposed” group) were obtained and categorized into five increasing exposure-severity classes based on the total number of standard reactors (to the single intra-dermal comparative cervical tuberculin test) detected during the breakdown. Exposed herds were deemed to be free of BTB after they passed a 6-month check test; non-exposed herds were deemed free as of the date of the first negative herd-test in 1995. In the 5 years after 1995, 18% of the non-exposed herds had a BTB breakdown, whereas 31% of the exposed herds had a subsequent breakdown. Relative to the hazard for non-exposed herds, the hazard for the first future singleton standard reactor breakdown, was 1.6-times higher for exposed herds with only 1 standard reactor in 1995, and 1.8-times higher for those exposed herds with 4–8 standard reactors during the 1995 episode. When the outcome for future breakdowns was 2 or more standard reactors, the hazard ratios ranged from 1.6 for exposed herds with only 1 standard reactor in 1995 up to 2.9 in exposed herds with 8 or more standard reactors during the 1995 episode. The latter hazard ratio varied over time, decreasing to 1.7 after 3 years of risk. The hazard of a future BTB breakdown increased directly with number of cattle in the herd, a positive history of previous BTB in the herd, and the local herd prevalence of BTB. The presence of confirmed BTB lesions in reactor cattle was not predictive of the future breakdown hazard when the effects of other factors were controlled.