The Incubation Period of Infectious Mononucleosis

Abstract

Of 410 personally examined patients with infectious mono-nucleosis, 7 previously had contacts with identifiable sources of the disease. The incubation period common to all 7 cases was 34 to 49 days, inclusive. A disproportionate number of married patients became ill 6 to 7 weeks after marriage. A 2-year record of mono- nucleosis indicence at West Point showed a significant difference between the monthly distribution of cadets and noncadet cases. In cadets, periods of greatest frequency followed periods of greatest liberty by 1 or 2 months. Mononucleosis occurred 21 days after blood transfussion from a donor in the preclinical phase of the disease. The incubation period of naturally acquired mononucleosis should be regarded as being about 33-49 days, at least until the data are controverted.