Viral infection in a child: Erythema infectiosum Flashcards
Define erythema infectiosum.
Erythema infectiosum is a childhood illness caused by infection with parvovirus B19. A ‘slapped cheek’ appearance with a lacy eruption on the torso and extremities is the most common presentation.
Parvovirus B19 infection can also be associated with arthropathy and a purpuric cutaneous eruption. Select populations may be at risk for chronic anaemia or transient aplastic crises. Fetal complications include hydrops fetalis and intrauterine fetal demise.
Explain the aetiology/risk factors of erythema infectiosum.
Erythema infectiosum is caused by parvovirus B19, a single-stranded, non-enveloped DNA virus. Humans are the only known hosts. Members of the family parvoviridae are frequent causes of infection in veterinary medicine but animal parvoviruses are not a cause of human infection.
Summarise the epidemiology of erythema infectiosum.
Erythema infectiosum is worldwide, can affect any age and can occur sporadically throughout the year. Epidemics are common and usually seen in the late winter and early spring and possibly follow a 6-year cycle. Spread is via direct contact and respiratory droplets, and infection is most common in school-aged children and household contacts.
The virus can be transmitted transplacentally from mother to fetus. Spread has also been reported via blood or blood products. Seroprevalence for parvovirus B19 increases with age and by 15 years old, over 50% of adolescents have antiparvovirus antibodies.
What are signs and symptoms of erythema infectiosum?
The most common tool in diagnosis of erythema infectiosum is the clinical appearance of the classic ‘slapped cheek’ rash with a lacy, reticular exanthem on the extremities and torso. There may or may not be a history of low-grade fever and non-specific influenza or respiratory symptoms occurring prior to onset of the exanthem.
Patients may develop arthralgia/arthritis, particularly of the small joints of the hands, wrists, knees or ankles, but these joint symptoms are usually self-limiting. When presented with this clinical scenario in an otherwise healthy individual, no other diagnostic investigations are required.
Immunodeficient patients do not form immune complexes, so they do not present initially with classic erythema infectiosum. This patient population includes patients with HIV, those receiving chemotherapy or immunosuppression following transplant, or patients with congenital immunodeficiencies. Persistent parvovirus B19 infection may occur, with resultant severe anaemia due to chronic red cell aplasia.
What are appropriate investigations for erythema infectiosum?
Clinical diagnosis
FBC
Reticulocyte count
Serology
DNA assays
What is the management of erythema infectiosum?
Acute: Paracetamol and supportive therapy + ibuprofen.
Secondary arthritis: NSAIDs
Persistent (> 3 weeks) Parvovirus B19 infection: Removal or reduction of underlying immunosuppression+ treatment with IVIG + RBC transfusion
What are complications associated with erythema infectiosum?
Severe fatal anaemia
Hydrops fetalis
Intrauterine death, transient aplastic crisis
What is the prognosis of erythema infectiosum?
Erythema infectiosum is self-limited and resolves without sequelae in the majority of cases.
Parents of children should be advised that the generalised exanthem may persist for several weeks and may intensify with increased body temperature (bathing, exertion), but this does not represent recrudescence of the disease.
In the immunosuppressed population, persistent B19 infection with resultant anaemia may occur.
