The TB Team in Welsh Government have provided an update on the disease picture in the Low TB North Wales area following recent outbreaks.
Epidemiological evidence shows that bought-in cattle are the primary source of new infections in the Low TB area of Wales.
Pre and Post-Movement Testing reduces, yet does not eliminate, this risk because cattle can become infected after being tested but before being moved, or because they may be at the earliest stages of infection when the test is conducted and therefore the infection is at too early a stage to be picked up.
Welsh Government states that in the longer-term, only a mandatory system will make sure all cattle sellers disclose the disease history of the herd at the point of sale.
Low TB Area Statistics
Open incidents
There were 27 open incidents at the end of March 2020, which is the highest number of open incidents since Quarter 2 2011. However, this only accounts for 1% of herds in the Low TB Area, with the remaining 99% free of TB at the end of March 2020. The Welsh Government says that at least 70% of the open breakdowns in the Low TB Area at the end of March 2020 are primarily attributable to cattle movements. This does not mean that the remaining 30% of breakdowns were not from purchased cattle but these breakdowns may have been exposed to more than one possible disease risk.
New incidents
There were 17 new TB incidents in the Low TB Area at the end of March 2020, which is the highest number of open incidents since Quarter 1 2016. However, there is some volatility with small numbers seen in the Low TB Area and remains low in proportion to the number of Officially TB Free (OTF) herd tests. During this quarter there were 1.7 new incidents per 100 OTF herd tests, which remains the lowest in Wales.
The source of purchased cattle varied between holdings. Around two-thirds of holdings purchased cattle from higher incidence areas with nearly a fifth of holdings sourcing over half of their purchased cattle from higher incidence areas.