Infectious mononucleosis
|
|
Infectious mononucleosis (also known as mono, the kissing disease, Pfeiffer's disease, and glandular fever) 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 through saliva or blood, often through kissing, or by sharing a drinking glass, an eating utensil or a needle, but the disease isn't very contagious. The virus is also found in the mucus of the infected person, so it is also easily spread through coughing or sneezing. It is estimated that 95% of adults in the world have been infected with the Epstein-Barr virus at some point in their lives. The most common age range of people who get mono is between the ages of 15-17.
The virus infects B cells (B-lymphocytes), producing a reactive lymphocytosis and the atypical T cells (T-lymphocytes) which give the disease its name.
| Contents |
Symptoms and physical signs
A person can be infected with the virus for weeks or months before any symptoms begin to appear. Symptoms usually begin to 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 lymph nodes - particularly the posterior cervical lymph nodes, on both sides of the neck.
- Sore throat (throat infection) - nearly all patients with EBV-mononucleosis have tonsillitis, usually accompanied by thick exudate.
- Fatigue (sometimes extreme fatigue)
Some patients may also display:
- Enlarged spleen or liver
- Abdominal pain
- Aching muscles
- Headache
- Loss of appetite
- Jaundice
- Sinus infection
- Depression
- Weakness
- Skin rash
The symptoms of infectious mononucleosis usually last 1-2 months, but 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.
Since mononucleosis can cause the spleen to swell, it may in rare cases 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). Infectious mononucleosis is rarely fatal, however death may result from severe hepatitis or splenic rupture.
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.
Symptoms similar to those of mononucleosis can be caused by adenovirus and the protozoan Toxoplasma gondii.
Laboratory tests
The laboratory hallmark of the disease is the presence of so-called atypical lymphocytes (a type of mononuclear cell) 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 cells. 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.
Treatment
Because mononucleosis is a viral infection, antibiotics are not effective. There is no specific treatment for mononucleosis, other than generic remedies to reduce the severity of the symptoms. 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. Duration of symptoms is very variable, ranging from weeks to months, but some cases have lasted from six months to a year. Even after the initial symptoms are gone, there may still be a risk of a ruptured spleen. Athletes involved in contact sports should receive medical clearance before resuming full activity.
Interactions with common drugs
- 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, corticosteroids may be judiciously prescribed, although some studies have shown that such treatment may increase the risk of the EBV virus causing lymphomas in later years.
External links
- CDC information on EBV (http://www.cdc.gov/ncidod/diseases/ebv.htm)
de:Drüsenfieber fr:Mononucléose infectieuse he:מחלת הנשיקה it:Mononucleosi id:Demam kelenjar nl:Klierkoorts pl:Mononukleoza zakaźna sv:Körtelfeber