Erythema Infectiosum: Symptoms, Diagnosis, Treatment

Erythema infectiosum is also called as fifth disease (this name comes from its place on standard list of rash-causing childhood diseases). It is generally a benign childhood condition described by a typical slapped-cheeked appearance & lacy exanthema. It is a viral infection caused by an erythrovirus i.e. human parvovirus. In this disease, a classic 3-phased cutaneous eruption pursued a rarely observed prodrome.

Etiology

It is caused by human parvovirus (PV) B19, a member of parvoviridae family. This virus has the smallest & a single stranded DNA core surrounded by an un-enveloped icosahedral capsid which causes illness in humans. Transmission occurs through respiratory secretions (in the form of fomites), from mother to fetus & by blood/blood products transfusion.

Pathophysiology

PV-B19, is a heat-stable, single-stranded DNA virus, it is the only parvovirus known to cause disease in humans. In children it normally produces erythema infectiosum while in an immuno-competent, acute infection leads to a Th-1 mediated cellular immune response with the synthesis of particular IgM antibodies and consequent development of immune complexes.

Signs & symptoms of erythema infectiosum result from the deposition of this immune complex in the skin and joints of affected individuals, not from the circulating virus. The incubation period can be 7-10 days to 4-21 days.

Signs & Symptoms

Mild symptoms appear approximately after 1 week of exposure & lasts for 2-3 days.

Such as:

• Headache (20% of pediatrics patients)
• Fever (20%)
• Sore throat (15%)
• Pruritus (15%)
• Coryza (10%)
• Abdominal pain (10%)
• Arthralgia (10%)

These symptoms are followed by a symptom-free phase of about 7-10 days, which is further chased by a classic exanthem that takes place in 3 phases even though some patients may possess no symptoms.

Phase1

The exanthema starts with a classic slapped-cheek presentation. The intense red, raised erythema appears suddenly over the cheeks & is marked by nasal, perioral, & periorbital sparing. It may emerge resembling sunburn, & is rarely edematous & normally fades within 2-4 days.

Phase2

This phase starts after 1-4days & is distinguished by an erythmatous maculopapular rash on proximal extremities i.e. arms & extensor surfaces & trunk, which fades into a classic lacelike reticular pattern as confluent areas clear.

Phase3

Repeated clearing & recurrences for weeks or months may take place due to stimuli such as physical activity, irritation, stress, & overheating of skin from sunlight or hot shower.

Diagnosis

The emergence & pattern of spread of the rash are the solitary diagnostic features; conversely, a number of enteroviruses may cause comparable rashes. Serologic testing is not compulsory; however, children with an acknowledged hemoglobinopathy or immunocompromised condition should have CBC and reticulocyte count to identify hematopoietic suppression as well as viral testing. In children with transient aplastic crisis or adults with arthropathy, the existence of IgM-specific antibody to parvovirus B19, strongly supports the diagnosis. Parvovirus B19 can also be detected by quantitative PCR techniques, which are usually utilized for patients with transient aplastic crisis, immunocompromised patients with pure RBC aplasia, and infants with hydrops fetalis or congenital infection.

Treatment

Symptomatic treatment is given only (because this disease is self-limiting) by NSAIDS (ibuprofen, diclofenac sodium, piroxicam, naproxen, flurbiprofen, indomethacin) to relieve fever, malaise, headache & arthralgia with antihistamines (hydroxyzine, diphenhydramine) & topical antipruritics. Plenty of fluids & rest is also recommended. In case of acute aplastic crisis, oxygen supply & blood transfusion is also essential. Intravenous immunoglobulin (IVIG) is cooperative for chronic anemia in immuno-compromised patients.