General Description: Mononucleosis is a viral illness frequently caused by the Epstein-Barr virus that causes fever, sore throat and swollen lymph nodes, enlarged spleen, generalized weakness and malaise, and atypical lymphocytes in the blood. The weakness and malaise resolve over weeks. The swollen glands and enlarged spleen regress over time. The severity of the illness is variable and infections are frequently unrecognized except by blood antibody tests. In cases of mononucleosis, estimates of spontaneous rupture of an enlarged spleen range from 0.1 to 0.2%.
Mode of Transmission: Person to person spread through saliva. Mononucleosis is known as the “kissing disease” because of its transmission among young adults.
Efficiency of Transmission/Attack Rate: In developed countries, persons frequently become infected with the Epstein-Barr virus in young adulthood. It is most commonly seen in high school students or young adults.
Period of Communicability: Many persons shed the virus for prolonged periods of time, up to 1 year and beyond.
Effect on LEO Fitness for Duty: Abdominal trauma may be encountered in routine patrol activities or training, so concern focuses on the risk of splenic rupture. One case series found that almost all splenic ruptures occurred between the 4th and 21st day of illness; in all cases, the spleen was enlarged, and in half the cases, there was no associated trauma. An evidence-based review of the medical literature stated that “clinical severity, laboratory results and physical exam are not reliable predictors of rupture (strength of association, case control study). Clinical evidence indicates that most splenic ruptures occur within 4 weeks of symptom onset, which correlates with ultrasound data showing resolution of splenomegaly by 30 days from symptom onset (strength of association, case-control study).”13 However, the review notes that there were no quality studies that evaluated the risks of physical activity in infectious mononucleosis. A consensus-based recommendation from the sports medicine literature suggests that contact sports may be resumed 4 weeks after symptom onset if there is no documentation of splenomegaly, the patient is clinically well, and all other complications were resolved.14
The LEO with mononucleosis who has recovered clinically may return to restricted duty. The restriction should be exclusion from physical training and routine patrol duties for 4 weeks from the onset of symptoms.
LEO-specific Clinical Studies and Reports: None known.