Erythema Infectiosum

Aetiology and epidemiology

Erythema infectiosum is caused by parvovirus B19, a highly infectious human pathogen found around the world. It is predominantly spread in respiratory droplets but can also pass from mother to fetus and in blood transfusions.

The incubation period for erythema infectiosum is usually between 4 and 14 days but can be as long as 21 days.

The infectivity period commences at exposure and lasts until the symptoms appear, i.e. at 4-14 days.

Clinical assessment

Fever and non-specific symptoms occur early and these are followed approximately 2-3 weeks later by a rash and arthropathy.

The classical rash is described as having a slapped cheek appearance and lasts for up to 4 days. The rash is a confluent, erythematous, oedematous rash with patches or plaques on cheeks, with sparing of nasal bridge and periorbital areas. This is followed by a maculopapular rash to the trunk and limbs. This rash can vary in intensity and duration. As the rash begins to fade it can take on a lacy appearance.

A broad spectrum of clinical presentations are associated with erythema infectiosum and these are presented on the next page.

Clinical presentations

The clinical presentations of erythema infectiosum are shown in Table 1.

Investigations

The majority of patients with erythema infectiosum do not need investigations unless there is a history of immunocompromise or haemoglobinopathy or unless a patient is pregnant.

Immunoglobulin M antibodies appear around 10 days post-infection and remain detectable for up to 2-3 months. Immunoglobulin G antibodies appear around 14 days post-infection and remain for life.

Management

Erythema infectiosum is a mild self-limiting illness for most children.

Treatment is largely symptomatic for the majority of patients, although analgesia may be needed to help the patient cope with joint pains.

Transfusion may also be indicated for patients with aplastic crises.

Intravenous immunoglobulin containing pooled neutralising anti-B19 antibody has been used to treat immunocompromised patients.

Pregnant women in contact with, or with, suspected parvovirus B19, should have serological testing. Referral to an obstetrician for regular monitoring and follow-up is also required.

Complications

Patients with haemoglobinopathies, immunocompromise or in pregnancy may experience complications if exposed to parvovirus B19. Under these circumstances, appropriate serological testing, investigations, management planning and follow-up are required.

Transient aplastic crises can also occur in those with, and without, underlying chronic haemolytic illness.

Viral transmission in pregnancy is more likely to occur during the first and second trimester. Foetal hydrops is more likely to occur in the second trimester. Estimated transplacental infection of women who are infected in pregnancy is around 30% with a 5-8% risk of foetal loss.