This is a very common question for a very common problem. 'Slapped cheek syndrome', sometimes referred to as erythema infectiosum or 'fifth disease', is caused by a virus called parvovirus B19. It is usually spread through coughing or sneezing, although it may also be transmitted from a mother to her unborn child with potentially fatal results, and also through blood transfusions.
It is so common that around six in every ten adults show evidence of previous parvovirus infection. Most cases occur in the winter or spring. Epidemics occur around every five years. Most cases are seen in children between five and 15 years of age, and girls are slightly more affected than boys.
INCUBATION AND SYMPTOMS
The incubation period - that is, the time between exposure to infection and symptoms appearing - is around a week to ten days, although some literature does quote up to three weeks. Symptoms are fairly non-specific in the early stage. They include headache, runny nose, sore throat and fever. Making a definite diagnosis of parvovirus at this stage is impossible without sophisticated blood tests.
Joint pains occur in around one in ten children, but one in two adults. The small joints of the hands are most commonly affected, and the arthritis associated with parvovirus may be mistaken for rheumatoid arthritis. In addition to the small joints of the hand, the wrists, knees and ankles may also become inflamed, but this occurs less frequently. Abdominal pain may also feature. Rarely, the virus affects the heart muscle, known as myocarditis; the covering of the brain, causing meningitis; or infection of the brain itself, known as encephalitis.
Just over a week after this initial phase, the cheeks appear very red in colour, giving the appearance of having been slapped. The skin around the mouth and the folds of skin from the nose to the mouth are usually not affected. A mild itchy rash on the arms and legs can also occur. Once the rash appears, the patient is no longer infectious.
RARE SCENARIO
Parvovirus infections in people with sickle cell anaemia, thalassaemia or other anaemias are susceptible to developing an aplastic crisis. In this rare scenario, the patient becomes severely deficient in all blood cells, causing anaemia, low white blood cells and low platelets.
Severe anaemia can cause breathlessness and cardiac failure. Low white cells renders the patient open to infections, which may be severe, and low platelets causes bruising and bleeding such as very heavy nose bleeds. This condition may be fatal. People who suffer an aplastic crisis continue to shed parvovirus until they have started making blood cells again.
IN PREGNANCY
Parvovirus infections contracted during the first 20 weeks of pregnancy may cause severe anaemia in the unborn child and miscarriage. Only women who have not been exposed to parvovirus in the past are at risk. Severe anaemia puts the heart under such strain that the foetus may die due to cardiac failure, a condition known as hydrops foetalis or foetal hydrops.
Research has shown, however, that fewer than one in ten women who contract parvovirus infection during the first half of their pregnancy go on to miscarry. Women are most vulnerable in the very early stages of their pregnancy. If a woman is exposed to somebody infected with parvovirus, she should be advised to see her GP.
Tests can then be done on the pregnant woman to assess whether she has previously been exposed or has a current infection. Foetal scans may be done in cases of maternal parvovirus infection and if the baby is affected, blood transfusions may be carried out in the unborn child, in order to treat the anaemia and prevent cardiac failure.
TREATMENT
There is no specific treatment for uncomplicated cases of slapped cheek syndrome. By the time the diagnosis is made - that is, when they have red cheeks - they are no longer infectious and it is too late to advise staying off school or staying away from pregnant women. People who are concerned about parvovirus infection should contact NHS Direct or their doctor. Useful information is found on the NHS Choices website at: www.nhs.uk/conditions/ slapped-cheek-syndrome/pages/introduction.aspx.
- Dr Raj Thakkar BSc(Hons) MBBS MRCGP MRCP(UK) is a full-time GP in Buckinghamshire
