Age-stratified patterns of reactors in Great Britain.

<p><b>A</b> The relative risk of infection by age RR(a) measured relative to the risk for 0–1 year old cattle, Error bars denote 95% credible intervals. RR(a) is calculated as the ratio of the force of infection for each age group divided by the estimate for the 0–1 year old group. The force of infection is a combined estimate for all national herds (beef and dairy) calculated from reactor cattle reported between 2004–2009 as described in [<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004038#pcbi.1004038.ref021" target="_blank">21</a>]. <b>B</b> The probability of “confirmation” of reactor animals by the presence of visible lesions or culture as a function of age at slaughter, estimated as the proportion of reactor animals within each (200 day) age-class that demonstrated visible lesions or a positive culture result. Estimates are calculated using all reactor animals from within our study population of herds. The qualitative pattern is robust between different test-types and parish testing intervals [<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004038#pcbi.1004038.ref021" target="_blank">21</a>].