PROBABLE INFECTIOUS MONONUCLEOSIS WITHOUT POSITIVE HETEROPHIL AGGLUTINATION TESTS

Abstract

In a series of 54 cases of infectious mononucleosis, 3 revealed no positive heterophile antibody test (5.5% incidence). The first two cases were dominated clinically by a septic type temperature of 3 weeks'' duration. The 3d case was characterized by 25 days of lower grade fever and pneumonia, with a rise of cold hemagglutinins. The outstanding clinical data are compared with two other reported groups of heterophile-negative cases which mimic infectious mononucleosis in some respects: 11 cases of "undescribed infectious exanthem" described by Blake, Welt and Craige in 1942; and 12 cases of "undefined virus disease" described by the writer in 1953. Although many explanations are advanced for the occasional failure to obtain a positive serologic test in infectious mononucleosis, the author favors two: (1) That two different but related viruses exist; or (2) that occasional individuals with the disease may be serologically "inert". The validity of the diagnosis of infectious mononucleosis in seronegative cases still remains to be established with certainty and will continue in some doubt until the etiologic agent is identified and an unquestioned diagnostic test results.