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result(s) for
"Marquetoux, Nelly"
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Evaluation of the accuracy of the IDvet serological test for Mycoplasma bovis infection in cattle using latent class analysis of paired serum ELISA and quantitative real-time PCR on tonsillar swabs sampled at slaughter
2023
Mycoplasma bovis
(Mbovis) was first detected in cattle in New Zealand (NZ) in July 2017. To prevent further spread, NZ launched a world-first National Eradication Programme in May 2018. Existing diagnostic tests for Mbovis have been applied in countries where Mbovis is endemic, for detecting infection following outbreaks of clinical disease. Diagnostic test evaluation (DTE) under NZ conditions was thus required to inform the Programme. We used Bayesian Latent Class Analysis on paired serum ELISA (ID Screen Mycoplasma bovis Indirect from IDvet) and tonsillar swabs (qPCR) for DTE in the absence of a gold standard. Tested samples were collected at slaughter between June 2018 and November 2019, from infected herds depopulated by the Programme. A first set of models evaluated the detection of active infection, i.e. the presence of Mbovis in the host. At a modified serology positivity threshold of
SP
%> = 90, estimates of animal-level ELISA sensitivity was 72.8% (95% credible interval 68.5%—77.4%), respectively 97.7% (95% credible interval 97.3%—98.1%) for specificity, while the qPCR sensitivity was 45.2% (95% credible interval 41.0%—49.8%), respectively 99.6% (95% credible interval 99.4%—99.8%) for specificity. In a second set of models, prior information about ELISA specificity was obtained from the National Beef Cattle Surveillance Programme, a population theoretically free—or very low prevalence—of Mbovis. These analyses aimed to evaluate the accuracy of the ELISA test targeting prior exposure to Mbovis, rather than active infection. The specificity of the ELISA for detecting exposure to Mbovis was 99.9% (95% credible interval 99.7%—100.0%), hence near perfect at the threshold SP%=90. This specificity estimate, considerably higher than in the first set of models, was equivalent to the manufacturer’s estimate. The corresponding ELISA sensitivity estimate was 66.0% (95% credible interval 62.7%-70.7%). These results confirm that the IDvet ELISA test is an appropriate tool for determining exposure and infection status of herds, both to delimit and confirm the absence of Mbovis.
Journal Article
Environmental, Occupational, and Demographic Risk Factors for Clinical Scrub Typhus, Bhutan
by
Phuentshok, Yoenten
,
Dorji, Kezang
,
McKenzie, Joanna
in
Aged patients
,
Animals
,
Annual reports
2023
Underdiagnosis and underreporting of scrub typhus has increasingly affected public health in Bhutan since its initial detection in 2008. Identifying scrub typhus risk factors would support early diagnosis and treatment for this nonspecific febrile disease, reducing the incidence of potentially fatal complications. We conducted a hospital-based, case‒control study during October‒December 2015 in 11 scrub typhus‒prone districts. We identified harvesting cardamom as the major risk factor (odds ratio 1,519; p<0.001); other factors were traditional housing, largely caused by an outside toilet location, as well as owning a goat and frequently sitting on grass. Harvesting vegetables, herding cattle in the forest, and female sex were protective. Age had a nonlinear effect; children and the elderly were more likely to seek treatment for clinical scrub typhus. This study has informed public health policies and awareness programs for healthcare workers through development of National Guidelines for Prevention, Treatment and Control of Scrub Typhus in Bhutan.
Journal Article
Evaluation of the accuracy of the IDvet serological test for Mycoplasma bovis infection in cattle using latent class analysis of paired serum ELISA and quantitative real-time PCR on tonsillar swabs sampled at slaughter
2023
Presents a descriptive analysis of serology conducted by the New Zealand Mycoplasma bovis (Mbovis) eradication programme between June 2018 and November 2019, and the outcomes of latent class analysis (LCA) conducted on paired serology and polymerase chain reaction (PCR) data collected by the programme at slaughter. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Journal Article
What Are Sheep Doing? Tri-Axial Accelerometer Sensor Data Identify the Diel Activity Pattern of Ewe Lambs on Pasture
2021
Monitoring activity patterns of animals offers the opportunity to assess individual health and welfare in support of precision livestock farming. The purpose of this study was to use a triaxial accelerometer sensor to determine the diel activity of sheep on pasture. Six Perendale ewe lambs, each fitted with a neck collar mounting a triaxial accelerometer, were filmed during targeted periods of sheep activities: grazing, lying, walking, and standing. The corresponding acceleration data were fitted using a Random Forest algorithm to classify activity (=classifier). This classifier was then applied to accelerometer data from an additional 10 ewe lambs to determine their activity budgets. Each of these was fitted with a neck collar mounting an accelerometer as well as two additional accelerometers placed on a head halter and a body harness over the shoulders of the animal. These were monitored continuously for three days. A classification accuracy of 89.6% was achieved for the grazing, walking and resting activities (i.e., a new class combining lying and standing activity). Triaxial accelerometer data showed that sheep spent 64% (95% CI 55% to 74%) of daylight time grazing, with grazing at night reduced to 14% (95% CI 8% to 20%). Similar activity budgets were achieved from the halter mounted sensors, but not those on a body harness. These results are consistent with previous studies directly observing daily activity of pasture-based sheep and can be applied in a variety of contexts to investigate animal health and welfare metrics e.g., to better understand the impact that young sheep can suffer when carrying even modest burdens of parasitic nematodes.
Journal Article
A synthesis of the patho-physiology of Mycobacterium avium subspecies paratuberculosis infection in sheep to inform mathematical modelling of ovine paratuberculosis
by
Marquetoux, Nelly
,
Ridler, Anne
,
Mitchell, Rebecca
in
carrier state
,
Causes of
,
Chronic granulomatous disease
2018
This literature review of exposure to
Mycobacterium avium
subsp.
paratuberculosis
(MAP) in sheep enabled a synthesis of the patho-physiology of ovine paratuberculosis (PTB). These results could be used to inform subsequent modelling of ovine PTB. We reviewed studies of both experimental and natural exposure. They were generally comparable. Possible outcomes following exposure were latent infection, i.e. mere colonization without lesions; active infection, with inflammatory histopathology in the intestinal tissues resulting in mild disease and low faecal shedding; and affection, with severe intestinal pathology, reduced production, clinical signs and high faecal shedding. Latent infection was an uninformative outcome for modelling. By contrast, histological lesions and their grade appeared to be a good marker of active infection and progression stages to clinical disease. The two possible pathways following infection are non-progression leading to recovery and progression to clinical disease, causing death. These pathways are mediated by different immune mechanisms. This synthesis suggested that host-related characteristics such as age at exposure and breed, combined with pathogen-related factors such as MAP dose, strain and inoculum type for experimental infection, have a strong influence on the outcome of exposure. The material reviewed consisted of disparate studies often with low numbers of sheep and study-level confounders. Hence comparisons between and across studies was difficult and this precluded quantitative model parameter estimation. Nevertheless, it allowed a robust synthesis of the current understanding of patho-physiology of ovine PTB, which can inform mathematical modelling of this disease.
Journal Article
Evaluation of post-exposure prophylaxis practices to improve the cost-effectiveness of rabies control in human cases potentially exposed to rabies in southern Bhutan
2020
Background
Rabies is endemic in southern Bhutan, associated with 1–2 human deaths and high post exposure prophylaxis (PEP) costs annually. Evaluation of clinicians’ management of human cases potentially exposed to rabies could contribute to improving PEP prescribing practices to both reduce unnecessary costs associated with PEP and reach the target of zero human deaths due to rabies by 2023.
Methods
A cross-sectional survey of 50 clinicians’ management of human cases potentially exposed to rabies was conducted in 13 health centers in high-rabies-risk areas of Bhutan during February–March 2016.
Results
Data were collected on clinicians’ management of 273 human cases potentially exposed to rabies. The 50 clinicians comprised health assistants or clinical officers (55%) and medical doctors (45%) with a respective median of 19, 21 and 2 years’ experience. There was poor agreement between clinicians’ rabies risk assessment compared with an independent assessment for each case based on criteria in the National Rabies Management Guidelines (NRMG). Of the 194 cases for which clinicians recorded a rabies risk category, only 53% were correctly classified when compared with the NRMG. Clinicians were more likely to underestimate the risk of exposure to rabies and appeared to prescribe PEP independently of their risk classification.. Male health assistants performed the most accurate risk assessments while female health assistants performed the least accurate. Clinicians in Basic Health Units performed less accurate risk assessments compared with those in hospitals.
Conclusions
This study highlights important discrepancies between clinicians’ management of human cases potentially exposed to rabies and recommendations in the NRMG. In particular, clinicians were not accurately assessing rabies risk in potentially exposed cases and were not basing their PEP treatment on the basis of their risk assessment. This has significant implications for achieving the national goal of eliminating dog-mediated human rabies by 2030 and may result in unnecessary costs associated with PEP. Recommendations to improve clinician’s management of human cases potentially exposed to rabies include: reviewing and updating the NRMG, providing clinicians with regular and appropriately targeted training about rabies risk assessment and PEP prescription, and regularly reviewing clinicians’ practices.
Journal Article
Clinicians management of patients potentially exposed to rabies in high-risk areas in Bhutan: A cross-sectional study
by
Dorji, Chendu
,
Kinley Penjor
,
Marquetoux, Nelly
in
Animal bites
,
Clinical medicine
,
Decision making
2018
Background: Rabies is endemic in southern Bhutan, associated with 1 2 human deaths annually and accounting for about 6% of annual national expenditure on essential medicines. A WHO-adapted National Rabies Management Guidelines (NRMG) is available to aid clinicians in PEP prescription. An understanding of clinical practice in the evaluation of rabies risk in endemic areas could contribute to improve clinicians PEP decision-making. Methods: A cross-sectional survey of clinicians was conducted in 13 health centers in high-rabies-risk areas of Bhutan during February March 2016. Data were collected from 273 patients examined by 50 clinicians. Results: The majority (69%) of exposure was through dog bites. Half the patients were children under 18 years of age. Consultations were conducted by health assistants or clinical officers (55%), or by medical doctors (45%), with a median age of clinicians of 31 years. Rabies vaccines were prescribed in 91% of exposure cases. The overall agreement between clinician s rabies risk assessment and the NRMG for the corresponding exposure was low (kappa =0.203, p<0.001). Clinicians were more likely to underestimate the risk of exposure than overestimate it. Male health assistants were the most likely to make an accurate risk assessment and female health assistants were the least likely. Clinicians from district or regional hospitals were more likely to conduct accurate risk assessments compared to clinicians in Basic Health Units (Odds Ratios of 7.8 and 17.6, respectively). Conclusions: This study highlighted significant discrepancies between clinical practice and guideline recommendations for rabies risk evaluation. Regular training about rabies risk assessment and PEP prescription should target all categories of clinicians. An update of the NRMG with more specific criterions for the prescription of RIG might contribute to increase the compliance, along with a regular review of decision-making criteria to monitor adherence to the NRMG.