Brucella Phagocytic Index Test

Abstract

Epidemiologists have observed that (a) a percentage of persons exposed to the risk of infection with Brucella-type abortus or suis-show either agglutinins or complement fixing antibodies in their serum and (b) clinical undulant fever is relatively infrequent in the occupational groups who come continuously and intimately in contact with Brucella organisms. Various inquiries leave no other explanation than that the Brucella abortus and probably the Brucella suis and melitensis as well are organisms endowed with a moderate degree of virulence, which rather frequently infect persons who are exposed either by contact through the skin or by alimentary ingestion. These infections are quite often subclinical and remain latent. Surveys in occupational groups have shown that the serologic tests fail to furnish a true picture of the number of unrecognized infections and therefore the allergic skin tests have been employed. Although a much more sensitive reagent to detect the existence of latent infections, the skin allergy is a variable state and in part influenced by the occupational activity. With the aid of this test one may recognize the allergic but not necessarily the latent infected and immune human being. The observations made by Huddleson, Johnson and Hamann 1 that the polymorphonuclear cells of persons who have had undulant fever in the past years or are actively infected or have no definite history of the disease may show a strikingly increased phagocytic activity offers a third procedure to detect latent infections. With the aid of a slightly modified Veitch technique 2 the usefulness of the method has been verified.