DISEASE IN CALVES.

New Zealand Herald, Volume LXVIII, Issue 20827, 20 March 1931, Page 16

DISEASE IN CALVES.

COMBATING TUBERCULOSIS.

A GREAT VACCINE

Tuberculosis in cattle—tho great scourge of farming—may ono flay be eliminated from the Empire's herds if the success of three years' experiments carried out at Cambridge University and financed by tho Empire Marketing Board is followed up. These experiments show that tho immunisation of calves against bovine tuberculosis with "8.C.G." vaccine is definitely practicable. This announcement has been made following tho claims recently put forward that calves had been rendered immune to tuberculosis by means of a secret vaccine used by Mr. Spahlinger on a farm in Norfolk. Tho Cambridge experiments, which began in 1927, aro being carried out by Professor J. B. Buxton, head of tho Department of Animal Pathology at the university, and Dr. Stanley Griffith, an officer of the Medical Research Council, with the aid of an Empire Marketing Board grant. Similar tests have been made at the Ministry of Agriculture's laboratories.

Alive Three Years Later. Many of tlie calves which were inoculated with B.C.G. vaccine, and subsequently given powerful doses of virile tuberculosis germs injected straight into the veins, were alive eight to twenty months afterwards. "Control" calves, which were not given the 8.C.G., but received the same dose of virulent tubercle germs, died in about three weeks. One animal which was vaccinated as a heifer calf and then given a fatal dose of tubercle germs is still alive and well three years afterwards. In the interval she has had a calf which does not react to the standard test for tuberculosis and so is free from infection.

"8.C.G." vaccine, or Bacillus-Calmette-Guerin, is so called because it was first discovered by a French scientist, Professor Calmette, at tho Pasteur Institute in 1906. It consists of a strain of living though non-virulent germs. These bacilli were bred for 13 years on bile-soaked potatoes in the laboratories and at the end of this time they were found to have lost their virulence and to be incapable of producing tuberculosis in _ calves, horses, etc., or even in guinea-pigs, the most susceptible of animals. Animals vaccinated with B.C.G. which were slaughtered over a year after severe intravenous injections of tubercle bacilli at Cambridge were found to be suffering only from slight chronic symptoms of the disease, although similar "control" calves —without the vaccine—died from acute tuberculosis in three weeks. Only One Failure.

B.C.G. vaccine does not always confer so high a degree of immunity. In some cases the vaccinated calves dje of tuberculosis or meningitis (caused by tubercle infection of the membranes of the brain) in three to seven months after infection. But in only one case has a calf intravenously vaccinated with B.C.G. failed to show increased resistance to tuberculosis.

These results are even more encouraging than they appear at first sight. In many of the tests tho calves are infected, with T.B. by the injection of millions of living germs into the blood-stream. This is very much more severe than the normal infection to whicli they aro exposed under farm conditions, when they pick up the germs by breathing or with their feed: It is safe to assume that where B.C.G. renders calves partially resistant to tuberculosis in laboratory tests it would have a very much greater effect under normal conditions.