Infectious mononucleosis

Infectious mononucleosis

Infectious mononucleosis: Due to Epstein-Barr virus, which belongs to the herpesvirus family. However, syndromes that mimic infectious mononucleosis can also be caused by other viruses, such as cytomegalovirus (CMV), toxoplasma (TXM), hepatitis A, and human immunodeficiency virus (HIV) protoinfection. The virus is usually transmitted by saliva (kissing disease) and rarely by blood. The incubation time is from a few days to a few weeks.

Fig.1: Symptoms of infectious mononucleosis

Clinical picture and examination

The clinical picture is intense, with the presence of fever, pharyngodynia with accompanying dysphagia and difficulty breathing, headache, myalgias and intense fatigue. The patient presents with painful cervical lymphadenopathy, with involvement of the posterior cervical lymph nodes, splenomegaly (50%) and hepatomegaly (10%). The disease varies in duration and severity, with mild manifestations at younger ages and more severe in adolescents and young adults (15-30 years). High fever and pharyngodynia resolve within one to two weeks, but cervical lymphadenopathy and fatigue may persist for months.

Fig.2: Exudation of parotid tonsils

During the clinical examination, there is marked swelling of the parotid tonsils, which can lead to obstructive symptoms, with the presence of exudate. Petechiae may be present on the palate, at the border of the hard and soft palate. The general blood count can show leukopenia, but more commonly there is leukocytosis, with an increase in lymphocytes and especially in the immature series. The presence of > 10% atypical lymphocytes is 92% specific for infectious mononucleosis. An increase in liver enzymes may be observed. Monotest is negative in 1/3 of patients during the first week, while 80% is positive during the second week and becomes negative after 3-6 months. In doubtful cases, IgM anti-capsid virus antibodies should be sought, which are positive for 90% in patients and persist for two to three months, whereas capsid (VCA) and core (EBNA) IgG persist for life.


Treatment is symptomatic with plenty of fluids, analgesics/anti-inflammatories and rest. Antibiotics may be given if a bacterial infection is suspected, but ampicillin or amoxicillin should be avoided, as it may cause a skin rash that can be mistaken for an allergic reaction. Corticosteroids are administered in case of obstructive phenomena, due to swelling of the tonsillar parsthmias. It is recommended to avoid any intense physical activity for a long time.

Fig.3: Skin rash from amoxicillin administration in infectious mononucleosis

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