Herd-level risk factors for infection with Mycobacterium paratuberculosis in US dairies and association between familiarity of the herd manager with the disease or prior diagnosis of the disease in that herd and use of preventive measures

Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St Paul 55108, USA.
Journal of the American Veterinary Medical Association (Impact Factor: 1.67). 05/2000; 216(9):1450-7. DOI: 10.2460/javma.2000.216.1450
Source: PubMed

ABSTRACT To evaluate associations among herd infection status, herd management practices, and familiarity of the herd manager with Mycobacterium paratuberculosis (Johne's disease) or prior disease diagnosis in that herd to support development of Johne's disease-control programs.
Population-based cross-sectional study.
1,004 US dairies, each with > or = 30 cows, representing 79.4% of US dairy cows.
Questionnaires were administered to dairy managers, and blood samples were collected from cows during herd visits. Sera were tested for antibodies to M paratuberculosis, using a commercially available ELISA. Multivariable logistic regression analyses were used to evaluate associations between use of management practices, herd disease status, and familiarity of the manager with Johne's disease or prior diagnosis of Johne's disease in that herd.
Results from serologic testing revealed that 3.4% of cows and 21.6% of dairy herds were infected with M paratuberculosis. Factors associated with infection included number of cows in herd, region of country, percentage of cows born at other dairies, group housing for periparturient cows, and group housing for preweaned calves. Few preventive practices were positively associated with prior diagnosis of Johne's disease (time of separation of newborn calf from dam) or familiarity of the manager with the disease (teats and udder washed before colostrum collected).
Risk factors associated with Johne's disease in this study confirmed those management practices generally recommended for disease control. An educational problem, however, is the finding that herd managers familiar with Johne's disease generally use management practices similar to those used by managers unfamiliar with the disease.

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    • "Without management changes designed to reduce the farm-level prevalence of MAP infection, it will continue to reduce farm income by increasing premature removal from the herd (Lombard et al 2005). MAP is usually introduced into dairy herds through the purchase of infected but clinically normal cattle (Sweeney 1996); other routes, such as the introduction of contaminated feces by vehicles or equipment are less common but may be involved (Wells and Wagner 2000). In a herd, younger animals are the most susceptible to MAP infection, especially shortly after birth. "
    Archivos de Medicina Veterinaria 12/2013; 46(1):39-44. DOI:10.4067/S0301-732X2014000100006 · 0.41 Impact Factor
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    • "There are other factors that appear to act in preventing seroprevalence (Muskens et al. 2003). Important preventive measures identified through risk analysis included limiting contact between the young stock and the adult herd, and correct hygiene and housing practices -given that faecal contamination of the animals' environment is one of the main ways that the infection is spread (Wells & Wagner 2000). There are a number of studies available which evaluate the potential risk factors associated with the transmission of paratuberculosis in cattle (Jakobsen et al. 2000, Daniels et al. 2002, Muskens et al. 2003, Dieguez et al. 2008). "
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    ABSTRACT: The aim of this study was evaluate the risk factors for Mycobacterium avium subsp. paratuberculosis (Map) seroprevalence in sheep in the North of Portugal. The effects on seroprevalence of several variables such as individual characteristics, management practices, farm characteristics, animal health, and available veterinary services were evaluated. This information was then used in a multivariable logistic regression model in order to identify risk factors for Map seropositivity. Univariable analysis was used to screen the variables used in the logistic regression model. Variables that showed p values of <0.15 were retained for the multivariable analysis. Fifteen variables were associated with paratuberculosis in univariable analysis. The multivariable logistic regression model identified a number of variables as risk factors for seropositivity like sheep pure local and/or a cross of a local breed (OR=2.02), herd size with 31-60 head (OR=2.14), culling during the Spring-Summer season (OR=1.69) and the use of an anti-parasitic treatment such as Ivermectin as the only anti-parasitic medication (OR=5.60). Potential risk factors identified in this study support current recommendations for the control of paratuberculosis.
    Pesquisa Veterinária Brasileira 11/2010; 30(11):903-908. DOI:10.1590/S0100-736X2010001100001 · 0.44 Impact Factor
    • "The authors explain this phenomenon by the increase in the number of susceptible animals in larger herds, in association with the decreased probability of effective contact. This finding contrasts with observed data from which the seroprevalence of paratuberculosis appears to be positively correlated to herd size (Wells and Wagner, 2000; Muskens et al., 2003). Herd size is likely to influence the results when modeling Map transmission within a cattle herd. "
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    ABSTRACT: Epidemiological models have been developed to test hypotheses on Mycobacterium avium ssp. paratuberculosis (Map) transmission in a herd, and to compare different paratuberculosis control strategies and alternatives for certification-and-surveillance schemes. The models are simplified representations of existing biological processes tailored to the questions they are intended to answer. Such models depend on available knowledge about the underlying processes, notably in relation to pathogen transmission. All decisions relating to integration of specific aspects of the herd structure and transmission mechanisms as well as modeling objective will influence model behavior and simulation results. This paper examines assumptions on pathogen transmission and risk mitigation represented in 8 epidemiological models of within-herd Map transmission in dairy cattle. We describe available models' structure and examine them in the context of current knowledge about host infection and pathogen transmission pathways. We investigate how population structure and herd management are modeled with regard to their influence on contact structure and pathogen transmission. We show that assumptions about routes of transmission and their contribution within a herd vary greatly among models. Gaps of knowledge that are pivotal to defining transmission equations and parameters, such as variation of susceptibility with age and variability of pattern of shedding, are identified. Quantitative estimates of this incomplete information should be targeted by future research. Existing models could be improved by considering indirect transmission via the environment taking account of Map survival and contact structure between animals in a herd, and by including calf-to-calf transmission, which has recently been proven as being important.
    Journal of Dairy Science 10/2010; 93(10):4455-70. DOI:10.3168/jds.2010-3139 · 2.55 Impact Factor
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