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Emergency And Acute Medicine - Erythema Infectiosum
Basic description
Erythema infectiosum is a characteristic viral exanthem, also known as fifth disease, historically the fifth most commonly described childhood rash. It typically presents with a mild viral prodrome followed by a “slapped-cheek” facial rash and a subsequent diffuse, lacy, reticular eruption, with or without arthropathy. It most commonly affects school-aged children younger than 14 years and is usually self-limited with lifelong immunity. Chronic or severe disease is rare but may occur in patients with congenital anemias or immunosuppression. Infection during pregnancy carries a risk of serious fetal complications.
Etiology
The condition is caused by human parvovirus B19, a small single-stranded DNA virus that infects human erythroid progenitor cells and transiently suppresses erythropoiesis. Transmission occurs via respiratory droplets, blood products, and vertical maternal–fetal spread. It is most common in late winter and spring. The incubation period ranges from 4 to 21 days, and patients are most contagious during the week before rash onset. Most adults have serologic evidence of prior infection.
Diagnosis – signs and symptoms
Young children typically develop a bright erythematous “slapped-cheek” rash accompanied by low-grade fever and malaise. Four to fourteen days later, a diffuse, pruritic, lacy rash may appear, most prominent on the extremities and usually sparing the palms and soles. Adolescents and adults may develop symmetric polyarthropathy, particularly involving small joints, while children more commonly experience knee involvement. Many patients remain asymptomatic or experience only mild viral symptoms.
History
Symptoms often begin with mild constitutional complaints such as fever, headache, nasal congestion, nausea, or sore throat. Patients are contagious only before the facial rash appears.
Physical examination
Stage one consists of coalescent, warm, erythematous, edematous facial papules with circumoral pallor. Stage two features a diffuse, maculopapular, reticular rash that may persist for weeks. Stage three is marked by fading of the rash with recurrence triggered by heat, sunlight, stress, or exercise, eventually resolving without scarring.
Essential workup
Diagnosis is clinical and based on classic presentation.
Diagnosis tests and interpretation
Laboratory testing is usually unnecessary. A CBC and reticulocyte count are indicated if aplastic crisis is suspected. In immunocompromised or pregnant patients, confirmation may be obtained with parvovirus B19 PCR or serology. IgM antibodies indicate acute infection, while IgG antibodies confirm immunity. Pregnant patients may require ultrasound monitoring for hydrops fetalis.
Differential diagnosis
Allergic reaction, drug eruption, nonspecific viral exanthem, measles, rubella, roseola, scarlet fever, erysipelas, infectious mononucleosis, collagen vascular disease, rheumatoid arthritis, sunburn, and enteroviral infections.
Treatment
The disease is typically self-limited and requires no specific therapy.
Prehospital care
Supportive care and standard ABCs for severe presentations.
Initial stabilization and therapy
Airway, breathing, and circulation management as needed. Supplemental oxygen and intravenous fluids may be required for severe dehydration. Severe anemia should be treated with packed red blood cell transfusion. Analgesia may be provided for arthropathy.
Emergency department treatment and procedures
No antiviral therapy or vaccine is available. Management is supportive, including antipyretics for fever, NSAIDs for joint pain if renal function permits, antihistamines for pruritus, and IV fluids when indicated. Immunocompromised patients with chronic infection or red cell aplasia may benefit from IVIG in consultation with infectious disease specialists. Hospitalization is indicated for aplastic crisis or severe complications.
Medication
Acetaminophen or ibuprofen for fever and pain. Diphenhydramine may be used for pruritus with caution regarding sedation. IVIG is reserved for select cases under specialist guidance.
Follow-up and disposition
Admission criteria
Aplastic crisis, severe anemia, hydrops fetalis, severe immunosuppression, toxic appearance, or debilitating arthritis.
Discharge criteria
Most patients can be safely discharged. Once the facial rash appears, patients are no longer contagious and may return to school or work if clinically stable.
Issues for referral
Hematology referral for patients with hereditary anemias or aplastic crisis. Infectious disease consultation for immunocompromised patients. Obstetric referral for pregnant patients with confirmed or suspected acute infection.
Follow-up recommendations
Pregnant patients with new infection require serial ultrasounds for 10–12 weeks. Patients at risk for aplastic crisis should have repeat CBC testing within 1–2 days.
Patient education
There is no vaccine. Hand hygiene reduces transmission. Children are usually no longer contagious by the time the rash appears, so exclusion from school is generally unnecessary.
Complications
Transient aplastic crisis in patients with underlying anemias, chronic anemia in immunocompromised individuals, arthropathy in adults, rare neurologic or cardiac involvement, and pregnancy-related complications including hydrops fetalis and fetal loss.
Clinical pearls and common missteps
Parvovirus B19 infection is usually mild and self-limited. Patients are not contagious once the rash appears. Always evaluate patients with anemia or immunosuppression for complications. Confirm infection in pregnancy and ensure appropriate fetal monitoring.
Basic description
Erythema infectiosum is a characteristic viral exanthem, also known as fifth disease, historically the fifth most commonly described childhood rash. It typically presents with a mild viral prodrome followed by a “slapped-cheek” facial rash and a subsequent diffuse, lacy, reticular eruption, with or without arthropathy. It most commonly affects school-aged children younger than 14 years and is usually self-limited with lifelong immunity. Chronic or severe disease is rare but may occur in patients with congenital anemias or immunosuppression. Infection during pregnancy carries a risk of serious fetal complications.
Etiology
The condition is caused by human parvovirus B19, a small single-stranded DNA virus that infects human erythroid progenitor cells and transiently suppresses erythropoiesis. Transmission occurs via respiratory droplets, blood products, and vertical maternal–fetal spread. It is most common in late winter and spring. The incubation period ranges from 4 to 21 days, and patients are most contagious during the week before rash onset. Most adults have serologic evidence of prior infection.
Diagnosis – signs and symptoms
Young children typically develop a bright erythematous “slapped-cheek” rash accompanied by low-grade fever and malaise. Four to fourteen days later, a diffuse, pruritic, lacy rash may appear, most prominent on the extremities and usually sparing the palms and soles. Adolescents and adults may develop symmetric polyarthropathy, particularly involving small joints, while children more commonly experience knee involvement. Many patients remain asymptomatic or experience only mild viral symptoms.
History
Symptoms often begin with mild constitutional complaints such as fever, headache, nasal congestion, nausea, or sore throat. Patients are contagious only before the facial rash appears.
Physical examination
Stage one consists of coalescent, warm, erythematous, edematous facial papules with circumoral pallor. Stage two features a diffuse, maculopapular, reticular rash that may persist for weeks. Stage three is marked by fading of the rash with recurrence triggered by heat, sunlight, stress, or exercise, eventually resolving without scarring.
Essential workup
Diagnosis is clinical and based on classic presentation.
Diagnosis tests and interpretation
Laboratory testing is usually unnecessary. A CBC and reticulocyte count are indicated if aplastic crisis is suspected. In immunocompromised or pregnant patients, confirmation may be obtained with parvovirus B19 PCR or serology. IgM antibodies indicate acute infection, while IgG antibodies confirm immunity. Pregnant patients may require ultrasound monitoring for hydrops fetalis.
Differential diagnosis
Allergic reaction, drug eruption, nonspecific viral exanthem, measles, rubella, roseola, scarlet fever, erysipelas, infectious mononucleosis, collagen vascular disease, rheumatoid arthritis, sunburn, and enteroviral infections.
Treatment
The disease is typically self-limited and requires no specific therapy.
Prehospital care
Supportive care and standard ABCs for severe presentations.
Initial stabilization and therapy
Airway, breathing, and circulation management as needed. Supplemental oxygen and intravenous fluids may be required for severe dehydration. Severe anemia should be treated with packed red blood cell transfusion. Analgesia may be provided for arthropathy.
Emergency department treatment and procedures
No antiviral therapy or vaccine is available. Management is supportive, including antipyretics for fever, NSAIDs for joint pain if renal function permits, antihistamines for pruritus, and IV fluids when indicated. Immunocompromised patients with chronic infection or red cell aplasia may benefit from IVIG in consultation with infectious disease specialists. Hospitalization is indicated for aplastic crisis or severe complications.
Medication
Acetaminophen or ibuprofen for fever and pain. Diphenhydramine may be used for pruritus with caution regarding sedation. IVIG is reserved for select cases under specialist guidance.
Follow-up and disposition
Admission criteria
Aplastic crisis, severe anemia, hydrops fetalis, severe immunosuppression, toxic appearance, or debilitating arthritis.
Discharge criteria
Most patients can be safely discharged. Once the facial rash appears, patients are no longer contagious and may return to school or work if clinically stable.
Issues for referral
Hematology referral for patients with hereditary anemias or aplastic crisis. Infectious disease consultation for immunocompromised patients. Obstetric referral for pregnant patients with confirmed or suspected acute infection.
Follow-up recommendations
Pregnant patients with new infection require serial ultrasounds for 10–12 weeks. Patients at risk for aplastic crisis should have repeat CBC testing within 1–2 days.
Patient education
There is no vaccine. Hand hygiene reduces transmission. Children are usually no longer contagious by the time the rash appears, so exclusion from school is generally unnecessary.
Complications
Transient aplastic crisis in patients with underlying anemias, chronic anemia in immunocompromised individuals, arthropathy in adults, rare neurologic or cardiac involvement, and pregnancy-related complications including hydrops fetalis and fetal loss.
Clinical pearls and common missteps
Parvovirus B19 infection is usually mild and self-limited. Patients are not contagious once the rash appears. Always evaluate patients with anemia or immunosuppression for complications. Confirm infection in pregnancy and ensure appropriate fetal monitoring.
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