Bovine TB in humans – the real facts

BC Plymouth recently published on its website a statement that: "In 2006, of nearly 300 cases of TB in the South West, six were transmitted from cattle to humans.  Last year there were two cases."

Trevor Lawson, the Trust’s public affairs adviser wrote to the station challenging the implication behind the statement and giving the full context.  He wrote: The Health Protection Agency's web site currently states: "The current risk posed by M.  bovis to human health in the UK is considered negligible."It goes on to explain: "Three quarters of the 440 human cases reported to the HPA between 1994 and 2006 were aged 50 years and above and only 44 cases (16%) were known to be non-UK born.   This suggests that a majority of the cases seen in the UK are attributable to reactivation of latent infection, probably acquired prior to more widespread implementation of controls, principally milk pasteurisation and meat inspection."

In other words, of the six cases that you refer to, all were actually transmitted prior to the pasteurisation of milk or were acquired outside the UK.   Your copy should make this clear.   Furthermore, the disease was not transmitted "from cattle to humans".  It is acknowledged that virtually all cases are transmitted from cattle milk to humans.  This is a significant difference and contradicts the claim made by Ian Johnson from the NFU that there is no risk from food or milk products.

Many of the emergent cases dating back to pre-pasteurisation infection result from the consumption of unpasteurised milk by farm workers.  The risk today is minimal, but exists nonetheless.  The meat from cattle slaughtered with bovine TB is sold into the food chain where, it is assumed, the disease will be killed by the heat of cooking.  Milk pasteurisation kills bovine TB and, provided EU rules are followed, milk from known TB-infected cattle must be dumped and not entered into the bulk tank of milk collected from the rest of the herd.  

The UK only updated its controls for these EU rules in 2007, however, following a visit by EU officials in 2006 (DG (SANCO) / 8323/2006).  Furthermore, the inadequacies and infrequency of the TB test mean that milk from TB-infected cattle will frequently enter the milk supply chain.  In 2004, for example, EU officials noted that: "some shortcomings were noted concerning the delivery of milk from inconclusive and reactor animals to milk establishments, and in GB this milk is also fed to calves without a prior heat treatment.  Moreover, milk from inconclusive and reactor animals can end up in a milk establishment of another Member State" (DG (SANCO) /7251/2004).The rules have been updated since 2004 but it is not clear that these are actively enforced, and so there is the theoretical possibility that, as a result of illegal activity, people in the UK and Europe could unwittingly consume dairy products containing unpasteurised milk from infected cattle.

(Signed) Trevor Lawson