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Parvovirus B19 infection

SNOMED: 710491002827 words•Updated 03/03/2026
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Exam Tips

  • Classic sequence: mild prodrome then "slapped cheek" rash followed by lacy reticular body rash; child often looks well.
  • High infectivity occurs before the rash, so by the time rash appears transmission risk is much lower.
  • In OSCEs, always identify high-risk groups: pregnancy, haemolytic anaemia, and immunocompromise.
  • Key investigation logic in pregnancy: IgG+/IgM- means past immunity; IgG-/IgM- means susceptible and needs repeat testing after exposure window.
  • Parvovirus B19 uniquely links rash illness to aplastic crisis (reticulocytopenia) and non-immune hydrops fetalis.

Definition

Parvovirus B19 infection is a common viral illness in children that typically causes erythema infectiosum ("slapped cheek" or fifth disease) and a later lacy rash on the body. It is spread mainly via respiratory droplets, has an incubation period of about 14-21 days, and targets erythroid precursor cells, which explains its haematological and fetal complications in high-risk groups.

Pathophysiology

Parvovirus B19 is a small single-stranded DNA erythrovirus with tropism for rapidly dividing erythroid progenitors (via the P antigen), particularly in bone marrow and fetal liver. Viral replication temporarily suppresses erythropoiesis; in healthy children this is usually subclinical, but in people with high red-cell turnover (for example sickle cell disease, thalassaemia, hereditary spherocytosis) it can precipitate transient aplastic crisis with reticulocytopenia. In pregnancy, transplacental infection can cause severe fetal anaemia, high-output cardiac failure, and non-immune hydrops fetalis, typically a few weeks after maternal infection. Immune-complex mechanisms also contribute to rash and arthropathy, especially in adults.

Risk Factors

  • Age 6-10 years (peak clinical infection in children)
  • Close household/school exposure during community outbreaks (late winter and spring)
  • Pregnancy, especially infection between 9-20 weeks' gestation
  • Haemolytic or high red-cell-turnover disorders (for example sickle cell disease, thalassaemia, hereditary spherocytosis, autoimmune haemolytic anaemia)
  • Immunocompromise (for example HIV, chemotherapy, haematological malignancy, transplant recipients)

Clinical Features

Symptoms

  • Mild prodrome: low-grade fever, headache, coryzal symptoms, sore throat, abdominal discomfort
  • Pruritic or non-pruritic rash developing after prodrome
  • Arthralgia or symmetrical polyarthropathy (more common in adults, often small joints of hands/wrists, also knees/ankles)
  • Fatigue and malaise
  • In severe anaemia: breathlessness, lethargy, reduced exercise tolerance

Signs

  • Bright malar erythema with perioral pallor ("slapped cheek" appearance; see Figure: classic facial rash in paediatric viral exanthems)
  • Maculopapular eruption on trunk/limbs evolving to a lacy reticular pattern (see Figure: reticular exanthem pattern)
  • Usually systemically well child despite rash
  • In aplastic crisis: pallor, tachycardia, tachypnoea, possible flow murmur
  • Rare papular-purpuric gloves and socks syndrome

Investigations

Clinical diagnosis in otherwise healthy child with typical rash pattern:Typical biphasic exanthem; laboratory confirmation usually unnecessary
Parvovirus B19 IgM and IgG serology (pregnancy or significant diagnostic uncertainty):IgM positive suggests recent infection; IgG positive with IgM negative suggests past immunity
Parvovirus B19 PCR (viral DNA):High-titre viral DNA confirms active infection, especially useful in immunocompromise or equivocal serology
Full blood count with reticulocyte count:Anaemia with marked reticulocytopenia in transient aplastic crisis/pure red cell aplasia
Pregnancy fetal surveillance (specialist-led ultrasound +/- MCA Doppler):Evidence of fetal anaemia or non-immune hydrops typically appearing 3-5 weeks after maternal infection
Rubella testing in pregnancy when rash illness assessed:Used to exclude alternative congenital-risk viral exanthem

Management

Lifestyle Modifications

  • Provide safety-net advice: return urgently for reduced oral intake, breathing difficulty, severe lethargy, syncope, or signs of anaemia
  • Hydration and rest during febrile/prodromal phase
  • Explain infectivity is greatest before rash onset; once rash appears, exclusion from school/nursery is usually not required if otherwise well
  • Pregnancy exposure or suspected maternal infection requires same-day discussion with virology/microbiology and obstetric team
  • Advise high-risk contacts (pregnant, immunocompromised, chronic haemolytic disorders) to seek prompt medical assessment after exposure

Pharmacological Treatment

Analgesic/antipyretic

  • Paracetamol oral: children 3 months-15 years 15 mg/kg every 4-6 hours (max 4 doses in 24 hours); age-band dosing per BNF can be used
  • Paracetamol oral: adults and >=16 years 500 mg-1 g every 4-6 hours when needed (max 4 g/day)

First-line for fever/discomfort. Check total daily dose from all formulations to avoid hepatotoxicity; use weight-based dosing in children.

NSAID (if needed for pain/arthralgia)

  • Ibuprofen oral (child >=3 months and >=5 kg): 5-10 mg/kg per dose 3 times daily (max 30 mg/kg/day)
  • Ibuprofen oral (adult): 200-400 mg up to 3 times daily with food; use lowest effective dose for shortest duration

Avoid in dehydration, active GI ulceration, severe renal impairment, NSAID hypersensitivity, and aspirin-sensitive asthma; caution if varicella is possible.

Specialist therapy for severe/complicated disease

  • Human normal immunoglobulin (IVIG) for chronic parvovirus-associated pure red cell aplasia in immunocompromised patients (for example 400 mg/kg/day for 5 days, specialist protocol)
  • Red cell transfusion for severe symptomatic anaemia/aplastic crisis (haematology-led)

Reserved for hospital specialist care. Monitor for transfusion reactions/volume overload; IVIG dosing and repeat courses are individualized.

Surgical / Interventional

  • Intrauterine transfusion for severe fetal anaemia/hydrops fetalis due to maternal parvovirus B19 infection (fetal medicine specialist procedure)

Complications

  • Transient aplastic crisis with severe anaemia and absent reticulocyte response
  • Pure red cell aplasia/chronic marrow suppression in immunocompromised patients
  • Non-immune hydrops fetalis due to fetal anaemia
  • Fetal loss (risk increased with infection before 20 weeks, especially 9-20 weeks)
  • Maternal mirror syndrome (pre-eclampsia-like oedematous state associated with fetal hydrops)
  • Neurological complications (for example encephalitis, meningitis, stroke, peripheral neuropathy; rare)
  • Myocarditis/cardiomyopathy, hepatitis, nephritic syndrome, vasculitis (rare)

Prognosis

In immunocompetent children, prognosis is excellent: illness is usually mild and self-limiting, with lifelong immunity after infection. The rash may recur transiently with heat, sunlight, or stress. Adult arthropathy can persist for weeks to months but usually settles. Prognosis is more guarded in pregnancy, immunocompromise, and underlying haemolytic disorders because of risks of fetal complications or severe anaemia.

Sources & References

✅NICE Guidelines(1)

📖Textbook References(13)

  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1475, 1476)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1476, 1477)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1342)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1498)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1476)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1497, 1498)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1341, 1342)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1341, 1342)[context]
  • [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 354, 355)[context]
  • [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 87, 88)[context]
  • [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 343)[context]
  • [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 86, 87)[context]
  • [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 355)[context]

Sources

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