Infectious diseases in children: Fifth disease (Slapped cheek disease)

Fifth disease, also known as erythema infectiosum and slapped cheek disease, is one of the common viral rash-causing diseases of childhood. This article describes the disease, explains why it matters and reviews the characteristics of the viral exanthems that it can resemble

What's in a name? Many diseases are named after the person who first described them. However, Fifth was not a person but a number, and the name dates back to Victorian times, when bacteria and viruses had not yet been identified and diseases were often named after their appearance. The problem for the Victorians was that fifth disease looks like a whole lot of red rashes; it was hard — at times — to find a way of distinguishing between them, and so an attempt was made to classify them.

In the late 1890s,¹ a list of common childhood exanthems (red rashes) was drawn up. First disease was measles, second scarlet fever, third rubella, fourth 'Duke's disease' (probably staphylococcal scalded skin syndrome) and sixth was roseola.

Fifth disease was also thought to be related to rubella and called erythema infectiousum. Later it acquired the colloquial and descriptive name of slapped cheek disease, after the characreristic appearance of patchy bright red cheeks. This name is now been immortalised by a Read code and that tends to be the name we use.

In Hungary it is called butterfly pox and in Japan, apple sickness.

CAUSATIVE AGENT

Fifth disease is one manifestation of infection by the erythrovirus, which is also previously called parvovirus B19. As is the case with strep pyogenes (which can cause scarlet fever), the erythrovirus does not always cause slapped cheek disease: about 20% of infections are asymptomatic.²

Transmission is via respiratory droplet infection and the virus is contagious, so outbreaks in nursery and preschool are common.³

THE DISEASE

In young children Fifth disease is normally a mild, short disease, although the facial rash can look quite dramatic. It has incubation period of anything from a few days to nearly three weeks.

The full syndrome begins with a mild fever, a headache and prodromal URTI symptoms such as a stuffy nose and sometimes nausea. These last only a few days, and tend to pass off as the rash appears. Often the first presentation to the nurse or doctor is with the rash.

The facial rash is the most obvious sign of Fifth disease. The florid red patches on the cheeks — hence 'slapped cheek disease' — can cross the bridge of the nose too.

The rest of the body may also develop a rash, particularly on the arms and legs, and by the time it appears the patient is no longer infectious.

The rash, which is often pale and lacy, can last days or weeks and it can come and go recurrently over this time, particularly on exposure to sunlight. It can be itchy, particularly on the soles of the feet and, unless the classic slapped cheeks are seen and noted, there are multiple differential diagnoses.

In Fifth disease the period of contagiousness ends with the appearance of the rash. Table 1 provides a reminder of some of the features of the common red rashes of childhood.

TREATMENT

None is needed and in fact there is none to give other than antipyretics and, if needed, calamine or other soothing creams for the rash.

WHY IT MATTERS

Fifth disease is usually a mild, self-limiting viral illness seen in children under 5 years. Its importance to the practice nurse is threefold:

• It is one of the differential diagnoses of a red rash in a mildly unwell young child with a fever.
• Like many childhood viral illnesses the disease is a worse in adults, who tend to develop marked arthralgia
• The virus has haematological effects on red cell production: these are mild and transient, so of minor or no significance in healthy people. However, they can cause catastrophic anaemia those with inherited red cell abnormalities such as congenital spherocytosis and sickle cell disease, and to the developing fetus.

TEENAGERS AND ADULTS

In teenagers and in adults, Fifth disease is more unpleasant, a pattern seen in several other viral childhood illnesses including chicken pox, rubella and glandular fever. The facial rash is less common but a painful multi-joint arthritis develops. This is symmetrical, affecting small and large joints of hands, feet, knees, shoulders, elbows, causing pain and stiffness. The only clues to the cause of the symptoms may be contact with an affected child, unless serology is checked. However, the arthropathy can last weeks or even months and the differential diagnosis as such a long time passes will include rheumatoid arthritis and other inflammatory arthropathies.

It is useful therefore to keep this diagnosis in mind in patients who present with joint pains, although by the time months have elapsed serology may be unhelpful. The usefulness of serology as a diagnostic test depends on picking up two or more changing immune responses to a recent infection, as the pattern of immunoglobulins in the body changes from none, prior to infection, to IgM, which is the body's first defence, followed by IgG which initially rises then eventually sinks to a baseline low positive level.

PREGNANCY

Fifth disease can be unpleasant and fairly long lasting in older sufferers. Its consequences in pregnancy are more serious: infection between week 9 and week 20 can result in severe foetal anaemia, with a significant risk of hydrops fetalis, or foetal heart failure, which can be fatal to the developing baby.^4,5

In women diagnosed with new parvovirus infection during pregnancy serial scans are offered to look for signs of developing fetal hydrops. It is possible to support the fetus through the disease with in-utero transfusion, until the effect of the virus passes. This is a risky and difficult procedure, but it does offer hope. It is also important to remember that most of women who contract Fifth disease in pregnancy suffer no foetal harm.

Who is at risk of pregnancy complications?

In the UK, around 70% of women are immune prior to pregnancy due to earlier exposure (immunity is usually long term). When infection does occur in this critical period, 5—10% of those affected will experience harm to their baby, falling to less than 1% where infection occurs later than 20 weeks).⁵

It is therefore essential to offer pregnant woman serological testing if they either

• have contact with a red rash which could have been Fifth disease
• develop an unexplained red rash, or
• develop unexplained multi-joint arthralgia

An initial blood test will look for pre-existing immunity, and a follow-up compares antibody levels to ascertain if they are rising, suggesting recent exposure.

Pregnancy and Fifth disease: what to do

Most pregnant women will have had Fifth disease in childhood (although they are rather less likely to know this than in the case with chicken pox). The first action, therefore, if a woman has knowingly contacted Fifth disease is to check for existing immunity. (Contact with a red rash of unknown origin should lead to testing serology for immunity to both Fifth disease and rubella).

Those who had the disease are likely to have long-term immunity.

SUMMARY

Most of the common viral exanthems of childhood have particularly specific features. However these are not invariably present, and the diagnostic sieve must always include meningococcal disease and Kawasaki disease.

Fifth disease causes a fever and rash, but it is not often confused with either of these two. Its importance lies with those — many — patients who might have encountered it when pregnant or those with compromised immunity or red cell structure abnormalities. With no cure and no vaccine, it will remain an important part of our knowledge bank for the foreseeable future.

REFERENCES

1. Lissauer T and Clayden G; Illustrated Textbook fo Paediatrics 4th Ed 2011 pub Mosby

2. Medline Plus (US National Library of Medicine) - Fifth Disease - http://www.nlm.nih.gov/medlineplus/fifthdisease.html

3. GP notebook: Fifth Disease - http://www.gpnotebook.co.uk/simplepage.cfm?ID=127533056

4. Patient.co.uk Parvovirus Infection (including erythema infectiosum) http://www.patient.co.uk/doctor/Parvovirus-Infection-%28Including-Erythema-Infectiosum%29.htm

5. Staroselsky A et al. Exposure to fifth disease in pregnancy. Can Fam Physician. 2009;55(12):1195-8 http://www.cfp.ca/content/55/12/1195.ful