Erythema Infectiosum (Fifth Disease - Parvovirus B19)
Overview
Plain-Language Overview
Erythema Infectiosum, also known as Fifth Disease, is a common viral illness that mainly affects children. It is caused by the parvovirus B19 and primarily involves the skin and blood cells. The disease is best known for its distinctive red rash on the face, often described as a 'slapped cheek' appearance. It can also cause a mild fever, runny nose, and joint pain in some cases. The infection usually resolves on its own without serious complications, but it can affect the bone marrow and cause anemia in certain individuals. The virus spreads through respiratory secretions, making it contagious during the early stages. Overall, it is a generally mild illness that affects the skin and blood system.
Clinical Definition
Erythema Infectiosum is an acute viral exanthem caused by parvovirus B19, a single-stranded DNA virus that targets erythroid progenitor cells in the bone marrow. The infection leads to a characteristic immune-mediated rash and mild systemic symptoms, primarily affecting children. The hallmark clinical feature is the 'slapped cheek' facial rash, followed by a lacy, reticular rash on the trunk and extremities. The virus's tropism for erythroid precursors can cause transient erythroblastopenia, which is clinically significant in patients with underlying hemolytic anemias or immunodeficiency. Transmission occurs via respiratory droplets, and the incubation period is typically 4 to 14 days. Diagnosis is important due to potential complications such as aplastic crisis and fetal hydrops in pregnant women. The disease is self-limited in immunocompetent hosts but can have serious hematologic consequences in vulnerable populations.
Inciting Event
Inhalation of respiratory droplets containing parvovirus B19 initiates infection.
Close contact with an infected person during the prodromal phase triggers transmission.
Exposure to contaminated fomites in daycare or school environments.
Vertical transmission from mother to fetus during maternal viremia.
Blood transfusion with infected blood products in rare cases.
Latency Period
The incubation period is typically 4-14 days after exposure to the virus.
Rash usually appears 1-2 weeks after initial nonspecific symptoms.
Arthritis symptoms may develop days to weeks after rash onset.
Aplastic crisis occurs during the acute viremic phase before rash appears.
Fetal hydrops develops 1-2 weeks after maternal infection.
Diagnostic Delay
Early nonspecific symptoms such as mild fever and malaise are often mistaken for viral upper respiratory infections.
The characteristic rash may be absent or atypical in adults, leading to misdiagnosis.
Arthritis symptoms can mimic rheumatoid arthritis or other autoimmune diseases.
Lack of awareness of parvovirus B19 as a cause of aplastic crisis delays diagnosis in hemolytic patients.
Serologic testing is not routinely performed early, delaying confirmation.
Clinical Presentation
Signs & Symptoms
Prodromal flu-like symptoms including low-grade fever, malaise, and headache precede rash onset.
Slapped cheek appearance with bright red facial rash is the hallmark sign.
Lacy, reticular rash develops on the trunk and limbs days after facial rash.
Mild arthralgia or arthritis occurs mainly in older children and adults.
Transient aplastic crisis may present with fatigue and pallor in patients with hemolytic anemia.
History of Present Illness
Initial prodrome includes low-grade fever, malaise, and upper respiratory symptoms lasting 1-2 days.
After 1-2 weeks, a bright red 'slapped cheek' rash appears on the face.
A lacy, reticular rash develops on the trunk and extremities following the facial rash.
In adults, symmetric small joint arthritis of the hands, wrists, and knees may occur.
Patients with hemolytic anemia may report sudden onset of fatigue, pallor, and dyspnea due to aplastic crisis.
Past Medical History
History of chronic hemolytic anemia such as sickle cell disease or thalassemia increases risk of aplastic crisis.
Previous episodes of immune-mediated arthritis may be relevant in adults.
Immunosuppressive conditions or therapies may predispose to persistent infection.
Pregnancy history is important due to risk of fetal complications.
No prior vaccination or immunity to parvovirus B19 is typical as no vaccine exists.
Family History
No known hereditary syndromes directly associated with erythema infectiosum.
Family members in close contact may have recent history of similar rash illness.
Genetic hemolytic disorders such as sickle cell disease or thalassemia may be present in family history.
No familial predisposition to severe complications from parvovirus B19 infection is established.
Awareness of family members with autoimmune arthritis may be relevant in adult presentations.
Physical Exam Findings
Characteristic slapped cheek rash with bright red erythema on the cheeks sparing the nasolabial folds.
Lacy, reticular, or net-like erythematous rash on the trunk and proximal extremities appearing after the facial rash.
Mild fever and pharyngitis may be present during the prodromal phase.
Mild cervical lymphadenopathy can be observed in some cases.
Arthralgia or arthritis primarily affecting small joints may be seen in adolescents and adults.
Diagnostic Workup
Diagnostic Criteria
Diagnosis of erythema infectiosum is primarily clinical, based on the presence of the classic slapped cheek rash and subsequent reticular rash on the body. Confirmation can be achieved by detecting parvovirus B19-specific IgM antibodies in serum, indicating recent infection. PCR testing for viral DNA may be used in immunocompromised patients or atypical cases. Laboratory findings may show transient anemia or reticulocytopenia due to bone marrow suppression. The combination of characteristic rash and serologic evidence is sufficient for diagnosis in most cases.
Pathophysiology
Key Mechanisms
Parvovirus B19 infects and destroys erythroid progenitor cells in the bone marrow, causing transient erythroblastopenia.
Immune complex deposition leads to the characteristic slapped-cheek rash and lacy reticular rash on the body.
Viral replication in the respiratory epithelium facilitates spread and initial symptoms of malaise and fever.
In patients with underlying hemolytic disorders, increased red cell destruction combined with marrow suppression causes aplastic crisis.
In some adults, immune-mediated arthritis occurs due to immune complex formation triggered by the virus.
| Involvement | Details |
|---|---|
| Organs | Lymph nodes may be involved due to immune activation during infection. |
Spleen participates in immune clearance of infected cells and immune complexes. | |
| Tissues | Bone marrow is affected due to viral infection of erythroid progenitor cells causing transient erythroblastopenia. |
Skin shows immune-mediated inflammation resulting in the characteristic slapped-cheek rash. | |
| Cells | Erythroid precursor cells are the primary target of parvovirus B19, leading to transient aplastic crisis in susceptible individuals. |
T lymphocytes mediate the immune response responsible for the characteristic rash and joint symptoms. | |
| Chemical Mediators | Interferon-gamma is involved in antiviral immune responses against parvovirus B19. |
Cytokines such as tumor necrosis factor-alpha contribute to systemic symptoms like fever and malaise. |
Treatments
Pharmacological Treatments
Acetaminophen
- Mechanism:
Inhibits central prostaglandin synthesis to reduce fever and alleviate mild pain.
- Side effects:
Hepatotoxicity with overdose
Rare allergic reactions
- Clinical role:
First-line
NSAIDs
- Mechanism:
Inhibit cyclooxygenase enzymes to reduce inflammation, fever, and joint pain.
- Side effects:
Gastrointestinal irritation
Renal impairment
Increased bleeding risk
- Clinical role:
Supportive
Non-pharmacological Treatments
Rest and hydration to support recovery during the febrile and symptomatic phases.
Avoidance of contact with pregnant women to prevent fetal complications from parvovirus B19 infection.
Prevention
Pharmacological Prevention
No approved vaccine or antiviral prophylaxis is available for parvovirus B19.
No routine use of immunoglobulin prophylaxis except in select immunocompromised patients.
Non-pharmacological Prevention
Avoidance of close contact with infected individuals during the contagious viremic phase reduces transmission.
Good hand hygiene and respiratory etiquette limit spread of respiratory droplets.
Screening and counseling pregnant women about exposure risks to prevent fetal infection.
Isolation of infected children from school or daycare during the febrile and early rash phase.
Outcome & Complications
Complications
Transient aplastic crisis in patients with underlying hemolytic disorders causing severe anemia.
Hydrops fetalis and fetal loss due to parvovirus B19 infection during pregnancy.
Chronic arthritis resembling rheumatoid arthritis in adults.
Pure red cell aplasia in immunocompromised patients with persistent infection.
| Short-term Sequelae | Long-term Sequelae |
|---|---|
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Differential Diagnoses
Erythema Infectiosum (Fifth Disease - Parvovirus B19) versus Rubella
Erythema Infectiosum (Fifth Disease - Parvovirus B19) | Rubella |
|---|---|
Rash has a characteristic 'slapped cheek' appearance followed by a lacy reticular rash on the trunk and limbs | Rash begins on the face and spreads downward, is maculopapular, and fades in 3 days |
Mild or absent prodromal symptoms, sometimes mild fever and arthralgia | Mild fever, lymphadenopathy, and arthralgia are common |
Positive parvovirus B19 IgM serology or PCR | Positive rubella IgM serology or PCR |
Erythema Infectiosum (Fifth Disease - Parvovirus B19) versus Measles
Erythema Infectiosum (Fifth Disease - Parvovirus B19) | Measles |
|---|---|
Rash has a slapped cheek appearance with a lacy reticular pattern on the body | Rash starts at hairline and spreads downward, is confluent and maculopapular |
Mild or absent prodrome, no Koplik spots | High fever, cough, coryza, conjunctivitis, and Koplik spots on buccal mucosa |
Transient anemia due to erythroid precursor infection | Transient immunosuppression with lymphopenia |
Erythema Infectiosum (Fifth Disease - Parvovirus B19) versus Scarlet Fever
Erythema Infectiosum (Fifth Disease - Parvovirus B19) | Scarlet Fever |
|---|---|
Slapped cheek rash with lacy reticular rash on trunk and limbs | Fine, sandpaper-like rash starting on the neck and trunk, sparing the face except for circumoral pallor |
Usually no pharyngitis or tonsillar exudates | Pharyngitis with tonsillar exudates and strawberry tongue |
Positive parvovirus B19 serology or PCR | Positive rapid antigen detection test or throat culture for group A Streptococcus |
Erythema Infectiosum (Fifth Disease - Parvovirus B19) versus Kawasaki Disease
Erythema Infectiosum (Fifth Disease - Parvovirus B19) | Kawasaki Disease |
|---|---|
Lacy reticular rash following slapped cheek appearance | Polymorphous rash often involving the trunk and extremities, not a lacy pattern |
Mild or absent fever, no mucous membrane or extremity changes | Fever lasting >5 days, conjunctival injection, mucous membrane changes, cervical lymphadenopathy, and extremity changes |
Supportive care; no specific treatment required | Responds to intravenous immunoglobulin and aspirin |
Erythema Infectiosum (Fifth Disease - Parvovirus B19) versus Roseola Infantum (HHV-6)
Erythema Infectiosum (Fifth Disease - Parvovirus B19) | Roseola Infantum (HHV-6) |
|---|---|
Common in children 5-15 years old | Typically affects infants 6-24 months old |
Mild or absent fever, rash appears without preceding high fever | High fever for 3-5 days followed by sudden onset of maculopapular rash as fever resolves |
Slapped cheek rash followed by lacy reticular rash on trunk and limbs | Rash starts on the trunk and spreads to face and extremities, not a slapped cheek pattern |