(also known in North America as '''mono''', '''the kissing disease''' or '''Pfeiffer's disease''', and more commonly known as '''glandular fever''' in other English-speaking countries) is a
Disease seen most commonly in adolescents and young adults, characterized by
Fever , sore throat and fatigue. It is caused by the
Epstein-Barr Virus (EBV) or the
Cytomegalovirus (CMV). It is typically transmitted from asymptomatic individuals through
Saliva or
Blood , or by sharing a drinking glass, eating utensils, or needles. The disease is far less contagious than is commonly thought. Since the causative virus is also found in the mucous of the infected person, it can also spread through
Cough ing or
Sneezing .
It is estimated that 90% of adults in the world have EBV-antibodies, having been infected with the Epstein-Barr virus at some point in their lives. The vast majority of infections do not result in the development of mononucleosis. The virus infects
B Cell s (B-lymphocytes), producing a reactive
Lymphocytosis and the atypical
T Cell s (T-lymphocytes). Early childhood infections often cause no symptoms. In developed countries with less crowded conditions and better hygiene, children do not commonly become infected until adolescence. Since they also typically begin dating at that age, the co-occurrence of mono and kissing have led to its being called the "kissing disease," although this is but one of its modes of transmission.
The disease is so-named because the count of ''mononuclear leukocytes'' (white blood cells with a one-lobed nucleus) rises significantly. There are two main types of mononuclear leukocytes:
Monocyte s and
Lymphocyte s. They normally account for about 35% of all white blood cells. With Mono, it can become 50-70% Also, the total white blood count increases 10000-20000 per cubic millimeter.
The incidence of clinically recognizable infectious mononucleosis caused by EBV is estimated at 45 per 100 000 in the US.
In developing countries, an estimated 90% of children undergo an asymptomatic EBV-infection, and thus are not susceptible to infectious mononucleosis of EBV.
A person can be infected with the virus for weeks or months before any symptoms appear. Symptoms usually appear 4-7 weeks after infection, and may resemble strep throat or other bacterial or viral respiratory infections. These first signs of the disease are commonly confused with cold and flu symptoms. The typical symptoms and signs of mononucleosis are:
- Fever - this varies from mild to severe, but is seen in nearly all cases.
- Enlarged and tender Lymph Node s - particularly the posterior Cervical lymph nodes, on both sides of the neck.
- Sore Throat - seen in nearly all patients with EBV-mononucleosis
- Fatigue (sometimes extreme fatigue)
Some patients also display:
After an initial prodrome of 1-2 weeks, the fatigue of mono often lasts from 1-2 months. The virus can remain dormant in the B cells indefinitely after symptoms have disappeared, and resurface at a later date. Many people exposed to the Epstein-Barr virus do not show symptoms of the disease, but carry the virus and can transmit it to others. This is especially true in children, in whom infection seldom causes more than a very mild illness which often goes undiagnosed. This feature, along with mono's long
Incubation Period , makes
Epidemiological control of the disease impractical. About 6% of people who have had mono will relapse.
Mononucleosis can cause the
Spleen to swell, which in rare cases may lead to a
Ruptured Spleen . Rupture may occur without trauma, but impact to the spleen is usually a factor. Other complications include
Hepatitis (inflammation of the liver) causing jaundice, and
Anaemia (a deficiency of red blood cells). In rare cases, death may result from severe hepatitis or splenic rupture.
Reports of
Splenomegaly in infectious mononucleosis suggest variable prevalence rates of 25% to 75%. Among pediatric patients, a splenomegaly rate of 50% is expected,
with a rate of 60% reported in one case series.[2 Although splenic rupture is a rare complication of infectious mononucleosis, it is the basis of advice to avoid contact sports for 4-6 weeks after diagnosis.
Usually, the longer the infected person experiences the symptoms the more the infection weakens the person's immune system and the longer he/she will need to recover. Cyclical reactivation of the virus, although rare in healthy people, is often a sign of immunological abnormalities in the small subset of organic disease patients in which the virus is active or reactivated.
Although the great majority of cases of mononucleosis are caused by the E.B. virus,
Cytomegalovirus can produce a similar illness, usually with less throat pain. Due to the presence of the atypical lymphocytes on the blood smear in both conditions, most clinicians include both infections under the diagnosis of "mononucleosis." Symptoms similar to those of mononucleosis can be caused by
Adenovirus and the
Protozoa n ''
Toxoplasma Gondii ''.
In small children, the course of the disease is frequently asymptomatic. The course of the disease can also be chronic. Some patients suffer fever, tiredness, lassitude (abnormal fatigue), depression, lethargy, and chronic lymph node swelling, for months or years. This variant of mononucleosis is often referred to as chronic EBV syndrome or
Chronic Fatigue Syndrome . In case of a weakening of the immune system, a reactivation of the Epstein-Barr Virus is possible, though the course of the resultant disease is usually milder.
The laboratory hallmark of the disease is the presence of so-called
Atypical Lymphocyte s (a type of mononuclear cell, see image) on the peripheral blood smear. In addition, the overall white blood cell count is almost invariably increased, particularly the number of lymphocytes.
The ''mono spot'' tests for infectious mononucleosis by examining the patient's blood for so-called ''heterophile''
Antibodies , which cause agglutination (sticking together) of non-human red blood cells. This ''screening test'' is non-specific. Confirmation of the exact etiology can be obtained through tests to detect antibodies to the causative viruses. The mono spot test may be negative in the first week, so negative tests are often repeated at a later date. Since the mono spot test is usually negative in children less than 6-8 years old, an EBV
Serology test should be done on them if mononucleosis is suspected.
An older test is the Paul Bunnell test, in which the patient's serum is mixed with
Sheep Red Blood Cell s. If EBV is present, antibodies will usually be present that cause the sheep's blood cells to agglutinate. This test has been replaced by the ''mono spot'' and more specific EBV and CMV antibody tests.
Because mononucleosis is a
Viral infection,
Antibiotic s are not effective, but a recent study in Minnesota demonstrated that 3 grams a day of the antiviral Valtrex (acyclovir or valacyclovir) for two weeks (or longer) is effective in treating mono (
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Another antiviral, valganciclovir (Valcyte) which has a longer intracellular half-life, may be even more effective than Valtrex.
Most doctors recommend generous amounts of bed rest, drinking a lot of fluids, and avoiding
Caffeine . Trying to be active to beat the fatigue may make it worse. The duration of symptoms may vary from weeks to months, with some cases lasting from six months to a year. Even after the initial symptoms are gone, there may still be a risk of rupturing the
Spleen .
Athlete s involved in
Contact Sport s should receive medical clearance before resuming full activity.
- Aspirin should be avoided, since its use in patients with mononucleosis can cause Reye's Syndrome .
- Paracetamol (acetaminophen) should be used with caution, as it may worsen the Hepatitis that often accompanies mononucleosis.
- Ampicillin and Amoxicillin should also be avoided, since they cause an allergic-like rash in 90% of mono patients. This rash may then be incorrectly diagnosed as an allergic reaction to Penicillin .
- In cases accompanied by severe throat pain, Corticosteroid s may be judiciously prescribed, although some studies have shown that such treatment may increase the risk of the EBV causing Lymphomas in later years.
