In 25-50% of cases, glandular fever reduces the production of the three types of blood cells. It can reduce levels of:
- red blood cells, which can make you feel tired and out of breath
- white blood cells, which can make you more prone to developing a secondary infection (see below)
- platelets, which can make you bruise and bleed more easily
In most cases, the reduction in the amount of blood cells is minimal and only causes mild symptoms.
In an estimated 1 in 100 cases, the Epstein Barr virus (EBV) can affect a person's nervous system and trigger a range of neurological complications, including:
- Guillain-Barré syndrome - the nerves become inflamed, causing symptoms such as numbness and temporary paralysis
- Bell's palsy - causes temporary weakness or paralysis of the muscles in one side of the face
- viral meningitis - an infection of the protective membranes that surround the brain and spinal cord; viral meningitis, although unpleasant, is much less serious than bacterial meningitis which is life-threatening encephalitis
- - an infection of the brain
These complications will usually pass once the underlying infection has resolved. Around four out of five people will make a full recovery.
Around half of people who develop glandular fever will have a swollen spleen. A swollen spleen does not present any immediate health problems, but it increases the risk of the spleen rupturing (splitting). The main sign of a ruptured spleen is the sudden onset of a sharp abdominal (tummy) pain.
Dial 999 for an ambulance if you have glandular fever and you suddenly experience abdominal pain. If you have a ruptured spleen, emergency surgery may be required to repair it.
The risk of the spleen rupturing is small, occurring in just 1 in every 1,000 cases, but it can be life-threatening because it causes severe internal bleeding.
A ruptured spleen usually occurs as a result of damage caused by vigorous physical activities, such as contact sports. It is therefore very important to avoid these activities for at least a month after the symptoms of glandular fever begin.
Be particularly careful during the second and third week of your illness as this is when the spleen is most vulnerable. Your GP can advise you about when it is safe to start doing vigorous physical activities again.
In a small number of glandular fever cases, the initial infection spreads to other parts of the body, leading to a more serious secondary infection. Possible secondary infections arising from glandular fever include:
Secondary infections usually only occur in people who have a weakened immune system (those who are immunocompromised), such as people with HIV or AIDS or those undergoing high-dose chemotherapy.
If you have a weakened immune system and you develop glandular fever, as a precaution you may be referred to hospital for specialist treatment. This will enable your health to be carefully monitored and any secondary infection to be treated.
Around 1 in 10 of people with glandular fever will experience prolonged fatigue which lasts for six months or more after the initial infection. It is not known why some people experience prolonged fatigue after having glandular fever.
Some experts think that it may be a form of chronic fatigue syndrome (CFS). This is a poorly understood condition that causes fatigue and flu-like symptoms, such as headache and joint pain.
Recent research in Australia suggests that particularly severe glandular fever infections may affect the nervous system at the genetic level, leading to prolonged fatigue. However, further research is required to explore this more fully.
From the evidence that is available, it seems that adopting a gradual exercise plan to rebuild your strength and energy levels is the best way to prevent prolonged fatigue.
Research has found that people who have had glandular fever are twice as likely to develop multiple sclerosis in later life compared with the population at large. However, it is important to put this increase in context. Multiple sclerosis is an uncommon condition, with 1 to 5 people in every 1,000 being affected at some point in their life. Therefore, the risk of someone who has had glandular fever developing multiple sclerosis later in life is very low.
There are two main theories to explain why there is an increase in risk of developing multiple sclerosis.
- glandular fever may affect some people's immune system in a way that causes it to malfunction many years after the original infection
- there may be certain genes that make some people more vulnerable to glandular fever and multiple sclerosis