Erythema infectiosum (human parvovirus or slapped cheek)

Notification requirement for erythema infectiosum

Notification is not required.

Primary school and children’s services centre exclusion for erythema infectiosum

Exclusion is not required.

Infectious agent of erythema infectiosum

The causative agent is human parvovirus B19.

Identification of erythema infectiosum

Clinical features

Asymptomatic infection with human parvovirus B19 is common (20–25 per cent). In children, it causes a mild illness with little or no fever but a striking ‘slapped cheek” rash on the face – hence the alternative name of ‘slapped cheek disease’. There is often a lacy red rash on the trunk and limbs that fades within a week, but may recur over several weeks on exposure to heat or sunlight. Headache, itch or common cold–type symptoms may precede the rash. In adults, the rash is often absent or atypical. Adults may have cold-like symptoms; sometimes, painful or swollen joints (arthralgias) lasting days to months or even years may occur, resembling rheumatoid arthritis.

Parvovirus affects the development of red blood cells. As a result, several groups of people are at increased risk of developing complications:

• Infection in the first half of pregnancy can cause fetal anaemia with hydrops fetalis (abnormal fluid accumulation in the fetus). Fetal death occurs in less than 10 per cent of these cases.
• People with haemolytic anaemia may develop transient aplastic crises (abnormal decrease in reticulocytes), often in the absence of a rash.
• Immunosuppressed people may develop severe chronic anaemia from red cell aplasia.

Diagnosis

Diagnosis can be suspected on clinical grounds, particularly during outbreaks. However, confirmation depends on demonstrating the presence of specific IgM antibodies against parvovirus B19 or a rise in B19 IgG antibodies. Comparison of the current antibody status against prenatal screening serology for parvovirus is often useful in pregnancy.

Specific IgM antibody titres decline 2–3 months after infection, while IgG levels, which appear 2 weeks after infection, can persist indefinitely.

Polymerase chain reaction (PCR) testing for B19 DNA is the most sensitive of tests. It will often be positive during the first month of acute infection and for prolonged periods in some people, particularly those with transient aplastic crisis or pure red cell aplasia.

Incubation period of human parvovirus B19

The incubation period varies from 4 to 20 days for development of rash or symptoms of aplastic crisis.

Public health significance and occurrence of erythema infectiosum

Human parvovirus infection occurs worldwide and is a common childhood disease. Outbreaks occur during winter and spring, with epidemics occurring every 3–4 years.

Up to 50 per cent of susceptible household contacts and 10–60 per cent of childcare or school contacts may be infected during outbreaks.

Reservoir of human parvovirus B19

Humans are the reservoir.

Mode of transmission of human parvovirus B19

The virus is transmitted by contact with infected respiratory secretions. It may be spread vertically from mother to fetus and, rarely, by transfusion of blood products.

Period of communicability of erythema infectiosum

Children with erythema infectiosum are most infectious before the onset of the rash and are probably not infectious after the rash appears.

Patients with an aplastic crisis are infectious for a week after the onset of symptoms.

Immunosuppressed people with chronic anaemia due to infection may excrete virus for years.

Susceptibility and resistance to erythema infectiosum

Infection generally confers immunity. Serological surveys suggest that 5–15 per cent of preschool children and 50–60 per cent of all adults are immune.

Control measures for erythema infectiosum

Preventive measures

There is no vaccine available.

All people who are nonimmune to parvovirus, are immunosuppressed, have chronic haemolytic disorders or are pregnant are at increased risk of complications.

These people should be advised of the risk that parvovirus infection may pose to them. They should avoid close contact with children or adults in settings where parvovirus infection may occur, such as schools, childcare centres and healthcare facilities.

Washing hands before eating or touching the face and practising cough etiquette can help prevent infection. Sharing of cutlery, cups and plates should be avoided.

Control of case

No specific treatment is required for uncomplicated infection.

Specialist advice should be sought if a patient with immunodeficiency or a blood disorder contracts parvovirus infection.

Control of contacts

Intrauterine infection may rarely result in fetal anaemia with hydrops fetalis or death if infection occurs within the first 20 weeks of pregnancy. Medical advice should be sought for pregnant women who have been in close contact with a case of parvovirus infection. Specific antibody testing (parvovirus IgG) should be performed to determine the woman’s immune status to parvovirus.

Control of environment

Not applicable.

Special settings

Patients and healthcare workers with acute parvovirus infection should not have contact with high-risk hospitalised patients, such as pregnant women, the immunosuppressed and those with a chronic haemolytic anaemia.

Outbreak measures for erythema infectiosum

General public health measures include:

• advising high-risk people of relevant outbreaks
• advising patients and contacts to observe strict hand washing after coughing and sneezing, and before eating.