The patient is usually an adolescent or a young adult between the ages of 15 and 25 who complains of several days of fever, malaise, lassitude, myalgias, and anorexia, culminating in a severe sore throat. The physical examination is remarkable for generalized lymphadenopathy, including the anterior and posterior cervical chains, and huge tonsils, perhaps meeting in the midline and covered with a dirty-looking exudate. There may also be palatal petechiae and swelling, periorbital edema (an early finding), splenomegaly (often not evident clinically), hepatomegaly, and, less commonly, a diffuse maculopapular rash or jaundice (more common in patients who are older than 40 years of age).
What To Do:
Perform a complete physical examination, looking for signs of other ailments and the rare complications of airway obstruction, encephalitis, hemolytic anemia, thrombocytopenic purpura, myocarditis, pericarditis, hepatitis, and rupture of the spleen.
Send blood samples to be tested. Obtain a differential white cell count (looking for atypical lymphocytes) and a heterophil or monospot test. Either of these tests, along with the generalized lymphadenopathy, will help confirm the diagnosis of mononucleosis. Atypical lymphocytes are less specific, because they are present in several viral infections.
Culture the throat or obtain a rapid Streptococcus test. Patients with mononucleosis harbor group A Streptococcus and require penicillin with approximately the same frequency as anyone else with a sore throat.
When the diagnosis has been confirmed, warn the patient that the period of convalescence for mononucleosis is longer than that for most other viral illnesses (typically 2 to 4 weeks, occasionally more) and that he should seek attention if he experiences lightheadedness, abdominal or shoulder pain, or any other sign of the rare complications mentioned earlier.
Symptomatic treatment is the mainstay of care. This includes adequate hydration, analgesics, antipyretics, and adequate rest. Bed rest should not be enforced, and the patient’s energy level should guide activity.
Patients should be warned that, in a few cases, fatigue, myalgias, and an excessive need for sleep may persist for several months.
Corticosteroids, acyclovir, and antihistamines are not recommended for routine treatment. If there is impending airway obstruction caused by tonsillar swelling, hospitalization is necessary, along with IV fluids, humidified air, and corticosteroids.
Dexamethasone, in doses up to 10 mg, has been used to treat impending airway obstruction caused by markedly enlarged “kissing tonsils.”
Arrange for medical follow-up.
What Not To Do:
Do not routinely begin therapy with penicillin for the pharyngitis, and certainly do not use ampicillin. In a patient with mononucleosis, ampicillin will produce an uncomfortable maculopapular rash (in 95% to 100% of cases), which incidentally does not imply that the patient is allergic to ampicillin.
Do not routinely evaluate the degree of splenomegaly with ultrasonography to determine when an athlete may return to contact sports. There is little evidence to support its routine use.
Do not unnecessarily frighten the patient about possible splenic rupture. If the spleen is clinically enlarged, he should avoid contact sports, but spontaneous ruptures are rare, usually occurring within 3 weeks of onset of symptoms, with an incidence of 0.1% to 0.5% (spontaneous or after mild trauma).
Infectious mononucleosis is caused by Epstein-Barr virus (EBV). EBV is a tumorigenic herpes virus that is ubiquitous in the adult population. EBV establishes a harmless lifelong infection in almost everyone worldwide and rarely causes disease unless the host-virus balance is upset. After an acute infection, a patient can shed and transmit virus through saliva for up to 3 months, and persistent virus shedding has been reported for up to 18 months. The incubation period for infectious mononucleosis is 4 to 8 weeks. In most cases, primary infection occurs subclinically during childhood, often spread between family members by salivary contact. It is commonly assumed that those who remain uninfected throughout childhood generally become infected as adolescents through kissing (thus it is called the kissing disease). It is when the primary infection is delayed until adolescence or beyond that clinical illness is caused by an intense immunopathologic reaction. Similar mononucleosis-like illnesses can be caused by other infectious agents, including cytomegalovirus, streptococcal infection, adenovirus, and Toxoplasma gondii. Infectious mononucleosis should be suspected in patients who are 10 to 30 years of age who present with sore throat, fever, and lymphadenopathy.
Atypical lymphocytosis of at least 20%, or atypical lymphocytosis of at least 10% plus lymphocytosis of at least 50%, strongly supports the diagnosis, as does a positive heterophil antibody test. False-negative results of monospot tests are relatively common early in the course of infection. Patients with negative results may have another infection, such as the examples given earlier. Although reasonably specific, positive tests are also seen in other conditions, including human immunodeficiency virus (HIV), lymphoma, systemic lupus, rubella, parvovirus, and other viral infections.
Mild thrombocytopenia, elevations of hepatocellular enzymes, microscopic hematuria, and proteinuria are often present but self-limiting abnormalities.
Although there are some cases of prolonged fatigue after infectious mononucleosis, there is no convincing evidence that EBV infection or recurrence of EBV infection is linked to a chronic fatigue syndrome. For previously healthy adolescents and young adults, infectious mononucleosis is a self-limited illness. Many have symptoms for less than 1 week, and most have returned to their usual state of health within a month.
Because concern for splenic rupture is the major consideration in limiting athletes from returning to strenuous sports, interestingly, more than half of the cases of splenic rupture related to infectious mononucleosis had no clearly notable previous trauma.