Abstract
The protective action of supplements of copper to the diets of rats against infections with Bartonella muris, Trypanosoma lewisi and Trypanosoma equiperdum has been reported. 1 , 2 , 3 The present communication deals with the effect of additions of copper salts to the diet on a subsequently induced infection with Mycobacterium tuberculosis (bovine strain) in albino rats. It was observed 4 that the adult rat of our stock, though highly resistant to tuberculous infection, could be infected with 0.1 mg. of a virulent bovine strain of tubercle bacilli and revealed gross lesions of tuberculosis in the lungs within a period of 3 to 5 months.
The rats are from the stock raised in our laboratory for many years and maintained under constant environmental and dietary conditions. The diet has been described 2 and was found to contain the equivalent of about 0.025 mg. of elemental copper per 15 gm. of food. Supplements of copper were given in the form of copper sulphate in amounts equivalent to 0.2 mg. of copper per rat per day.∗
Fifty-six rats were divided into 4 groups; 12 received daily supplements of copper in the amounts indicated above; 12 received supplements of iron; 12 received supplements of copper and iron. All supplements were commenced 14 days prior to the injection of the tubercle bacilli, and continued during the entire experimental period. Twenty rats were fed on the normal diet. Each of the rats was injected intraäbdominally with 0.1 mg. of bovine tubercle bacilli (“Ravenel”strain). All the animals were killed 5 months after the injection of the bacteria.
From the table it may be seen that of the rats receiving copper-supplements, 6 showed no evidence of tuberculous lesions at autopsy and 6 had a few scattered tubercles in the lungs (indicated in the table as “slight infections”).
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