The diagnosis of Brucella infections in man has usually been confirmed by a positive agglutination test or a positive blood culture. The agglutination reaction is of especial value, usually during the febrile stage of the disease, and for varying periods after the temperature has become normal. There may be marked variations in both the regularity and the titer of this reaction. A positive agglutination reaction is of great significance, but a negative reaction cannot be relied on particularly in this disease. A positive blood culture is diagnostic of undulant fever but there are certain difficulties which have not been overcome by the average laboratory in obtaining growth of the organism, so that at the present time only a small percentage of cases are diagnosed by this method. The allergic skin reaction is considered to be a dependable test to determine whether or not an individual is or has been infected
