Conditions
Erythema infectiosum (EI) is one of many disorders caused by infection with the Human Parvovirus B19 (B19).
Erythema infectiosum (EI) is one of many disorders caused by infection with the Human Parvovirus B19 (B19). Depending on the immunity of the patient, one of several conditions may appear:
- Erythema infectiosum,
- Arthritis,
- Anaemia, bone marrow suppression - possibly causing aplasia,
- Intra-uterine fetal death if the mother is infected, or
- Myocarditis - inflammation of heart muscle.
How is it spread?
The only known host for the B19 virus is human, so there are no animals carriers involved.
Sources of infection and transmission are varied:
- Respiratory: B19 is found in airways and lung secretions of infected patients, so inhalation of even tiny droplets can spread the infection.
- Blood: It has also been found in blood samples taken shortly before or after the onset of illness, making donated blood products another possible source of transmission.
- Environment: The virus can also survive in the environment, so that contaminated surfaces can provide a source of infection.
Symptoms
B19 infection in adults most often cause an arthritis which may be mistaken for rheumatoid arthritis. In children, the usual illness is that of EI, often as outbreaks at school. Most people with normal immunity have such mild symptoms that they go unnoticed.
Virus is present in the blood within a week of infection, and is followed by vague, non-specific symptoms such as:
- Fever,
- Runny nose,
- Headache - this is always significant in a child,
- Nausea, and
- Diarrhoea.
Two to five days later, the typical rash appears: flushed cheeks with paleness around the mouth. A rash may appear on the rest of the body as well. The rash fades in patches over a few days, leaving a lacy pattern. Normally, antibodies are produced, and these provide long-term immunity from reinfection.
EI typically is a mild disease, and resolves by itself, leaving no permanent problems.
Diagnosis
The diagnosis is purely clinical, based largely on the examination findings and the history given by the patient or parent.
Blood tests for antibody levels may be done if the symptoms are more severe than usual. For immune-compromised patients, a full blood count will detect bone marrow problems, which may need the attention of a haematologist.
Treatment
The symptoms of EI are usually mild, and even symptomatic treatment is seldom needed. In some adults, and very rarely in children, pain relief may be needed for arthritis.
There is no specific treatment for the virus itself.
Prevention
The best prevention is to prevent transmission from an infected host: good hygiene practices are the most effective:
- covering the mouth when coughing or sneezing,
- regular hand-washing, and
- cleaning of the environment near an infected patient.
There is no effective vaccine available at present.
Outcome
EI is a mild, self-limiting disease, with an excellent outcome and lifelong immunity against reinfection.
(Dr A G Hall)