Erythema Infectiosum (Fifth Disease) – A Complete Patient Guide

Overview

Erythema infectiosum, commonly known as Fifth disease, is a mild, self‑limited viral infection that primarily affects children. It is caused by parvovirus B19, a small DNA virus that targets red‑blood‑cell precursors in the bone marrow. The disease gets its “fifth” moniker from the historic classification of childhood rashes: first (measles), second (scarlet fever), third (rubella), fourth (diphtheria), and fifth (erythema infectiosum).

• Typical age group: 5–15 years, though it can occur in infants, adolescents, and adults.
• Prevalence: In the United States, serologic studies indicate that >50 % of children have been infected with parvovirus B19 by age 15 [1]. Outbreaks tend to be seasonal, peaking in late winter and early spring.
• Transmission: Respiratory droplets, close contact, or vertical transmission from mother to fetus.

Most infections are mild and resolve without complications, but certain groups—pregnant women, people with hemolytic anemias, or immunocompromised patients—may experience more severe outcomes.

Symptoms

Symptoms appear in three overlapping phases. Not every person experiences all phases.

1. Prodromal (pre‑rash) phase – 4–14 days

• Low‑grade fever (often < 38 °C/100.4 °F).
• Headache or mild malaise.
• Upper‑respiratory symptoms: sore throat, runny nose, or cough.
• Arthralgia (joint pain) may be present, especially in adolescents and adults.

2. Rash phase – 3–10 days

• “Slapped‑cheek” appearance: bright red facial erythema that spares the area around the mouth.
• Reticular (lace‑like) rash on the trunk, arms, and legs. The rash may become more pronounced when the child is warm or after a hot shower.
• Itching is usually mild but can be bothersome.

3. Late (post‑rash) phase – 2–4 weeks

• Rash fades, often leaving a faint pink discoloration that may persist for weeks.
• Joint pain may linger, especially in adults.

Rarely, patients may develop erythema multiforme‑like lesions or purpuric rashes if they have underlying blood‑forming disorders.

Causes and Risk Factors

Cause – Parvovirus B19

Parvovirus B19 is highly stable in the environment and spreads through:

• Respiratory droplets (coughing, sneezing).
• Direct contact with infected secretions.
• Maternal‑fetal transmission across the placenta (≈30 % of infections in pregnant women).

Risk Factors

• Age: Children in school or daycare settings have the highest exposure.
• Close‑contact environments: Military barracks, nursing homes, and households with multiple children.
• Pregnancy: Women in the 2nd trimester are at risk for fetal complications.
• Underlying hemolytic disorders (e.g., sickle cell disease, hereditary spherocytosis) because the virus destroys red‑cell precursors.
• Immunosuppression (e.g., HIV, chemotherapy) can lead to prolonged viremia and chronic anemia.

Diagnosis

Diagnosis is primarily clinical, supported by laboratory testing when the presentation is atypical or complications are suspected.

Clinical Evaluation

• Characteristic “slapped‑cheek” rash with preceding mild viral symptoms.
• History of exposure to school or daycare outbreaks.

Laboratory Tests

• Serology: Detection of IgM antibodies (appears 7–10 days after infection) confirms recent infection; IgG indicates past exposure and immunity.
• PCR (polymerase chain reaction): Detects viral DNA in blood, marrow, or amniotic fluid—useful in immunocompromised patients or pregnant women.
• Complete blood count (CBC): May show transient aplastic crisis (markedly low reticulocyte count) in patients with hemolytic anemia.
• Fetal monitoring: In pregnant women, ultrasound may be performed to assess for hydrops fetalis.

Treatment Options

Fifth disease is usually self‑limiting; treatment focuses on symptom relief and management of complications.

Symptomatic Care

• Fever & pain: Acetaminophen or ibuprofen (avoid aspirin in children).
• Itching: Calamine lotion, cool compresses, or antihistamines (e.g., cetirizine).
• Hydration: Encourage fluids, especially during fever.

Specific Interventions

• Aplastic crisis: Red blood cell transfusion for patients with severe anemia (e.g., sickle cell disease).
• Pregnancy: Close obstetric monitoring; in rare cases, intrauterine transfusion may be required for severe fetal anemia.
• Immunocompromised hosts: Intravenous immunoglobulin (IVIG) can hasten viral clearance and improve anemia.

When Medications Are Not Indicated

Antibiotics have no role because the illness is viral. Overuse contributes to antimicrobial resistance and should be avoided.

Living with Erythema Infectiosum (Fifth Disease)

Although the condition resolves in 1–3 weeks for most, the following tips help patients and families navigate the illness.

• School / daycare: Children can return once the fever resolves and the rash is no longer highly contagious—typically 5–7 days after rash onset.
• Comfort measures: Use soft, breathable clothing; keep the child’s skin cool to reduce rash intensity.
• Nutrition: Iron‑rich foods (lean meats, beans, leafy greens) support red‑cell production, especially important for children with pre‑existing anemia.
• Activity: Light activity is fine; avoid strenuous exercise if joint pain persists.
• Follow‑up: Schedule a pediatric visit if the rash does not fade after 3 weeks or if joint symptoms linger.
• Pregnant women: Report any suspicion of exposure to the obstetrician promptly; early serologic testing guides monitoring.

Prevention

Because parvovirus B19 spreads via respiratory droplets, the following measures reduce risk:

• Hand hygiene: Wash hands with soap for ≥20 seconds, especially after coughing or changing diapers.
• Respiratory etiquette: Cover mouth/nose with a tissue or elbow when coughing/sneezing.
• Avoid close contact: Keep children with active rash away from high‑risk individuals (pregnant women, immunocompromised patients) until the rash fades.
• Environmental cleaning: Disinfect frequently touched surfaces (doorknobs, toys) with EPA‑approved cleaners.
• Vaccination: No vaccine exists for parvovirus B19; prevention relies on the above behavioral strategies.

Complications

Complications are uncommon in healthy children but can be serious in vulnerable populations.

• Aplastic crisis: Sudden halt of red‑cell production leading to severe anemia; can be life‑threatening in sickle cell disease or hereditary spherocytosis.
• Fetal hydrops: Accumulation of fluid in the fetus associated with severe anemia—occurs in ~5 % of maternal infections during the second trimester [2].
• Chronic anemia: Persistent low hemoglobin in immunocompromised patients.
• Arthropathy: Joint pain may become chronic, especially in adult women, mimicking rheumatoid arthritis.
• Neurologic manifestations: Rare cases of encephalitis or Guillain‑Barré syndrome have been reported.

When to Seek Emergency Care

References

1. Mayo Clinic. “Parvovirus B19 infection (fifth disease).” Updated 2023. https://www.mayoclinic.org
2. CDC. “Parvovirus B19 (Fifth Disease) – Pregnancy.” 2022. https://www.cdc.gov
3. NIH National Library of Medicine. “Parvovirus B19 infection.” StatPearls Publishing, 2024. https://www.ncbi.nlm.nih.gov
4. Cleveland Clinic. “Fifth disease (erythema infectiosum).” 2023. https://my.clevelandclinic.org
5. World Health Organization. “Parvovirus B19 infection.” WHO Fact Sheet, 2022. https://www.who.int