Slapped Cheek Disease

Slapped cheek disease, also called erythema infectiosum or fifth disease, is caused by human parvovirus B19, a single stranded DNA virus that infects erythroid progenitor cells.

• Epidemiology: most common in school age children (4 to 10 years); late winter and spring epidemics; incubation 4 to 14 days (up to 21); spread by respiratory secretions (infectious before rash appears, not infectious once the rash is present), blood products and vertical transmission. About 50 to 60 percent of adults are immune.
• Presentations by host:
  • Healthy children: mild or asymptomatic; the classic facial rash.
  • Adults, especially women: acute symmetric polyarthropathy of small joints (hands, wrists, knees, ankles) lasting weeks to months, with or without the rash.
  • People with increased red cell turnover (sickle cell disease, hereditary spherocytosis, thalassaemia): transient aplastic crisis with sudden severe anaemia and reticulocytopenia.
  • Immunodeficient patients: chronic pure red cell aplasia.
  • Pregnancy: fetal infection can cause non-immune hydrops fetalis, anaemia and miscarriage; maternal infection before 20 weeks carries a fetal loss risk of about 10 percent (risk of hydrops about 3 to 4 percent overall; mostly 9 to 20 weeks); mothers rarely have severe illness.
  • Papular purpuric gloves and socks syndrome in young adults.

• Prodrome: low grade fever, malaise, headache, coryza, sore throat for 2 to 5 days.
• Rash in two stages: bright red, warm, non-tender "slapped cheek" erythema sparing the nasolabial folds and perioral area (2 to 5 days); then 1 to 4 days later a lacy, reticular, pink erythematous eruption on the trunk and extensor limbs that fades and recurs for 1 to 3 weeks (sometimes months) with heat, sunlight, exercise or stress.
• Adults: joint pain and swelling, morning stiffness.
• Aplastic crisis: pallor, fatigue, tachycardia, jaundice change, breathlessness, in the setting of a recent febrile illness (child or sibling contact).
• Red flags: pregnancy (exposure or infection), haemolytic anaemia, immunosuppression, severe anaemia, fever with petechiae, persistent joint swelling, neurological symptoms, prolonged hospital contact with pregnant women or those with haemolytic disease.

• Clinical diagnosis in a healthy child with the typical rash. No tests needed.
• Serology: parvovirus B19 IgM (positive from 7 to 10 days after infection and lasts 2 to 3 months) and IgG (immune); PCR for B19 DNA (immunocompromised, aplastic crisis, fetal infection).
• Pregnant women exposed or with rash: urgent IgG and IgM within 3 weeks of contact; if non-immune, repeat in 4 weeks; if recent infection, refer to fetal medicine for serial ultrasound and middle cerebral artery Doppler peak systolic velocity (above 1.5 multiples of the median suggests fetal anaemia) every 1 to 2 weeks for up to 12 weeks after infection.
• Aplastic crisis: full blood count with reticulocytes (absent), haemoglobin.
• Differentials: rubella, measles, scarlet fever, drug rash, enterovirus, systemic lupus erythematosus, juvenile dermatomyositis, contact dermatitis, sun exposure.

• Uncomplicated childhood infection: supportive. Reassure; paracetamol 15 mg/kg every 4 to 6 hours or ibuprofen 5 to 10 mg/kg every 6 to 8 hours for fever or discomfort; emollients and cool compresses for itch; keep fluid intake adequate; antihistamines for itch (cetirizine 2.5 mg twice daily for ages 1 to 5, 5 mg daily for 6 to 11 years).
• No antiviral or antibiotic. No exclusion from school after the rash appears, as the child is no longer infectious; advise nurseries and schools so pregnant staff and those with haemolytic anaemia can seek advice.
• Adult arthropathy: NSAIDs (ibuprofen 400 mg three times daily or naproxen 500 mg twice daily with food), rest; resolves in weeks; prednisolone 0.5 mg/kg short course rarely for severe cases.
• Aplastic crisis: hospital admission, red cell transfusion for severe anaemia (haemoglobin below 5 g/dL or symptomatic) in small volumes; precautions for contagiousness (infectious before and during crisis; isolate from pregnant women).
• Chronic infection in immunodeficiency: intravenous immunoglobulin 0.4 g/kg/day for 5 days or 1 g/kg/day for 2 days; reduce immunosuppression where possible.
• Fetal infection with hydrops or severe anaemia: intrauterine red cell transfusion by fetal medicine specialists.
• Hand hygiene, respiratory etiquette; pregnant healthcare workers should avoid contact with symptomatic patients.
• Follow up: not required in healthy children; in pregnancy, serial monitoring for 12 weeks.