IN his farming article in the Times of June 29 James McInnes addresses the issue of bovine tuberculosis. At the end he says: 'To reassure the public, TB in cattle is a different strain from the human one'. In itself this is a true statement, but the implication, for those who are not familiar with zoonotic (animal to human) diseases, is that they are not at risk from this organism. How wrong they will be to assume so.
Figures that I have just obtained from the Public Health Laboratory Service, Communicable Diseases Surveillance Service, show that between 1993 and the present there have been 291 cases of bovine TB infection reported in humans in the UK. Not a significant number you might think, but very unpleasant for those affected.
It may also be that there are a number of people out there 'carrying' the disease without showing symptoms but who could infect others — and maybe even their own cattle.
Indeed, the Merck Veterinary Manual states that '. . . in some European countries, pulmonary or genitourinary tuberculosis of man caused by bacilli of the bovine type is a source of infection in some herds where disease recurs'.
This implies that there are people working in the farming industry who are unaware that they are carrying the disease and who are infecting their own animals. The PHLS figures could therefore be deficient.
The Merck Veterinary Manual also says of this disease: 'The bovine type is capable of causing progressive disease in most warm-blooded vertebrates, including man'.
I hope that these observations will encourage people to appreciate the complex nature of disease transmission in the environment, and show that our activities have far reaching implications for both humans and other species.
David Spratt
Shell Park
North Brentor