1. Mononucleosis mostly presents as an indistinct blend of fatigue, fever, adenopathy and sore throat. The last two appear less often in older patients. There is one specific sign that accounts for many office diagnoses: swelling around the eyes, especially puffy upper eyelids.

2. Rather too many patients are diagnosed by trial and error: they’re prescribed cephalosporins, amoxicillin or ampicillin for suspected strep throat. Five times out of six, the patient with infectious mono will react to these antibiotics with a long-lasting, itchy maculo-papular rash.

3. The Epstein-Barr virus that causes IM infects about 95% of North American adults by age 40. Most are asymptomatic childhood infections. The majority of us are asymptomatic carriers who shed virus sporadically. While the likelihood of contracting EBV falls with age, the chance of IM symptoms increases, to about 50% by late adolescence. In N. America, black people hardly ever develop IM.

4. The typical case peaks after one week, then subsides by one month. Complications include splenomegaly (about 55%), transient non-pruritic maculo-papular rash (5%), jaundice (rare in the young, 20% in over-40s), abdominal pain, thrombocytopenia, and hemolytic anemia.

5. Rarer complications include: Guillain Barré syndrome, encephalitis, airway compromise, uveitis, retinopathy, hepatomegaly and acute hepatitis. The most notorious complication is splenic rupture (1-2 per 1,000 cases).

6. Differential diagnoses include toxoplasmosis, cytomegalovirus, leukemia, strep A, common cold, influenza, and acute onset of HIV. Be sure to exclude HIV — it’s been misdiagnosed as mono before.

7. The lab tests for EBV are specific and quite sensitive, but there are caveats. The commonest serological test, the Monospot, looks for heterophile antibodies, but these may not appear in the first week. In kids, they may never appear. Use viral capsid antigen IgM test in children, and after suspected false negative Monospots.

8. Treatment is supportive, with bedrest the key. Antivirals may reduce transmission but don’t mitigate symptoms and aren’t usually given. Saltwater gargles can help pharyngitis. Use NSAIDs for headache, pain and fever, avoiding aspirin of course. Corticosteroids are used when airway obstruction threatens, or in severe thrombocytopenia or anemia. Cut splenic rupture risk by barring contact sports for at least 1 month or until US-proved normal spleen.

9. EBV is a herpes family virus, less infectious than cold or flu. The monicker “kissing disease” has it about right. Special precautions are needed only around the immunocompromised. Reports of institutional outbreaks tend to be false.

10. The link to chronic fatigue syndrome remains unproven and controversial. On a purely technical level, if active EBV infection or IM is found, it excludes diagnosis of CFS.