History and exam

Key diagnostic factors

common

presence of risk factors

Risk factors include sexual activity and kissing.

fever

Ranges from 37.8°C (100°F) to 41.1°C (106°F); usually <38.9°C (102°F).

Lasts 1 to 2 weeks; rarely up to 5 weeks.

Occurs in 76% of cases.[34]

pharyngitis

Can be exudative or non-exudative.

Often resembles Streptococcus pyogenes pharyngitis.

Subsides by the second week.

Petechiae may be present on the soft palate.

Occurs in 84% of patients.[34]

cervical or generalised lymphadenopathy

Nodes typically tender, non-erythematous, and discrete.

Most prominent after second week of illness.

Occurs in 94% of cases.[34]

malaise

Occurs in 82% of cases.[34]

Other diagnostic factors

common

splenomegaly

Enlargement begins in the first week.

Lasts 3 to 4 weeks.

Occurs in 52 % of cases.[34]

uncommon

rash

Occurs in 10% of adults, but may present in up to one third of paediatric patients.[34]

Appears in the first days of illness; lasts for 1 week. Can be erythematous, maculopapular, or morbilliform.

A maculopapular pruritic rash is typically seen in adults with IM after starting treatment with ampicillin, amoxicillin, or beta-lactam antibiotics for pharyngitis.[45]

Mucosal rash and eyelid oedema more common in adults.

signs of hepatitis (hepatomegaly, jaundice)

Liver involvement is present in over 90% of IM cases, but it is often subclinical and self-limited. Jaundice is seen in a small minority (<5%) of patients.[46] Hepatomegaly is more common in young children, and occurs in 12% of cases.[34]

Systemic symptoms of IM are typically present when Epstein-Barr virus infection involves the liver, but in some cases hepatic involvement can also occur in isolation. Severe or fatal hepatitis has also been observed, especially in immunocompromised patients.[46] 

jaundice

Adults are less likely to have sore throat and lymphadenopathy, but more likely to have hepatomegaly and jaundice (due to hepatitis).[37] Liver involvement in acute EBV infection represents mild hepatitis with predominantly cholestatic features, but does not always manifest itself as a clinical jaundice.[47] The overall frequency of jaundice in adolescents and adults is about 9%.[34]

myalgia

Seen in 28% of patients at the time of initial presentation.[35]

Risk factors

weak

kissing

Epstein-Barr virus (EBV) is most commonly transmitted through saliva, hence the name ''kissing'' disease. In one study, all patients with EBV-caused IM shed virus from the oropharynx for 6 months after the disease onset.[23] In a prospective study, 22 out of 24 healthy individuals with past history of EBV infection shed virus in saliva for 15 months.[24]

sexual behaviour

The risk of Epstein-Barr virus infection increases with penetrative sexual intercourse and with increasing number of sexual partners in young women.[19][27]

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