The Diagnosis of Brucellosis

THE clinical diagnosis of undulant fever or brucellosis is frequently a matter of very great difficulty. This difficulty is made apparent by a short review of the opinions of various authors as they set them out in current textbooks of medicine. Thus, G. M. Low and N. H. Fairly in their contribution to Price's Textbook of Medicine (6th Edition) state that the differential diagnosis of undulant fever includes differentiation from "the enteric fevers, acute rheumatism, malaria, kala-azar, tuberculosis, subacute bacterial endocarditis, thoracic lymphadenoma associated with the Pel-Ebstein syndrome, amoebic abscess of the liver and occult pyogenic infections." H. L. Amoss, in Cecil's Textbook of Medicine (6th Edition), lists, in addition to the conditions cited above, influenza, tularmemia, acute appendicitis and chole-cystitis, go-norrhueal orchitis, arthritis, and neurasthenia as diseases, which infection with one of the brucella may simulate. When the protean symptomatology of the foregoing diseases is considered, it can be readily understood that the term brucellosis can cover almost any sympton to which medical science can ascribe a name. The textbooks lay great emphasis on the carrying out of agglutination tests in the detection of infection by the brucella. In practice, in the British Isles, it is sufficient only to consider those infections due to br. abortus, as the closely allied br. melitensis and br. suis do not occur. The agglutination test has a definite value, but further examination of the literature suggests that the investigation is not without its fallacies. For example, Carpenter and Boak (1930) noted that in 6 per cent. of their cases in which the brucella had been isolated from the blood the agglutination test was negative. Many other authors have reported the presence of agglutinins to brucella in sera giving positive reactions with B. The culture of br. abortus from the blood is a matter of some difficulty and, in view of the high incidence of contagious abortion in the cattle in Northern Ireland, it was decided to attempt to evaluate the presence of agglutinins to br. abortus in the blood. The sera of 2,073 apparently healthy blood donors were tested for specific agglutinins. Of these, 257 gave positive reactions to a titre of 1 in 10 or higher. This figure represents a percentage of 12.39. Huddleson (1943) states that a serum agglutination in a dilution of 1 in 40 or higher should be considered to be indicative of a past infection with br. abortus. …