The evaluation of rapid tests in human brucellosis.

Blood cultures and tube-agglutination tests performed as a matter of routine would reveal most cases of human brucellosis, but many laboratories are not equipped to perform them and prefer the more rapid slide-agglutination test for which, however, many commercial antigens are unsatisfactory. The skin test is also frequently used but there has been no satisfactory criterion for its interpretation. The author has therefore tried to improve certain rapid tests in order to get good qualitative results with a minimum of false-positive reactions. Details are given of the methods used in the spot test, the surface-fixation test, and the skin test. A careful comparison of the results of these tests with those of blood cultures and tube-agglutination tests showed that the spot and surface-fixation tests gave positive reactions in all proved cases of human brucellosis. The skin-test reactions, however, were 50% positive in the first three months of the disease rising to about 90% positive in the sixth month. A number of persons also had positive skin-test reactions but negative blood-cultures and negative or non-significant agglutination tests. The author concludes from his studies that use of the three rapid tests will reveal more suspected cases than either the blood culture or the tube-agglutination test. They should also prove more satisfactory than the skin-test alone or the slide-agglutination test, as they provide for quick bedside differentiation which may be rapidly corroborated. Whenever possible, however, patients should be referred to specialized laboratories for fuller testing.