CONTAGIOUS ABORTION

Waikato Times, Volume 124, Issue 20728, 11 February 1939, Page 26 (Supplement)

CONTAGIOUS ABORTION

RESISTANCE TO INFECTION RESEARCH IN AMERICA In most outbreaks of contagious abortion some cows in the diseased herds are resistant to infection. These resistant cows, states an American authority, do not abort. Their blood often does not show a positive reaction. The blood reaction, if it occurs is seldom strongly pronounced, and the animals soon cease to react. The question naturally arises, “What factors are responsible fori-the resistance of these animals which are able to throw off infection which causes serious disease in the great majority of cows similarly exposed to the infection? Supported in part by funds from the United States Department of Agriculture, two American research workers have been attempting to answer this question. Rabbits were first used as the experimental animals (rabbits do not contract contagious abortion naturally, but do show the characteristic abortion symptoms when certain abortus organisms are injected). The Americans, working on the belief that the power of the resistant animals to throw off infection was in some way associated with the ability of the blood of these resistant animals to kill the invading bacteria, devised a method of measuring in the laboratory the bacteriidal power of the whole blood. The data secured showed wide differences in the killing power of the whole blood. It was found that 86 per cent of the animals with blood having a low killing power proved susceptible when actually tested by injection, while 74 per cent of those having blood with a high killing power of the blood seemed definitely correlated with resistance to disease, and low killing power with susceptibility.