Common Skin Infections

Parvovirus infection 'Slapped cheek'

50% infections are asymptomatic. Otherwise there is commonly a biphasic illness consisting of a brief prodrome of a non-specific febrile illness with a cough, followed by recovery and approximately seven symptom free days. Then the classical fiery red, macular ‘slapped cheek’ rash develops which spares the area around the mouth (circumoral pallor) and has slightly raised edges. The rash spreads 1-4 days later to involve the trunk and limbs and becomes maculopapular, resolving with central clearing to form a lacy (reticular) pattern. It is most prominent on extensor surfaces and is itchy. It rarely affects the palms or the soles and can look very similar to rubella. It lasts 1-3 weeks and fluctuates with environmental factors e.g. it may flare after a hot bath.

Caused by Parvovirus B19 it is spread by droplets. It is usually benign but may cause the following problems:

• Joint involvement is rare in children but common in adult females (80% infections with a rash). In this group joint arthritis may occur without a rash, and is commonly a sudden onset symmetrical arthritis affecting the small joints of the hand, usually the proximal interphalangeal joints (PIPs). The arthritis usually resolves within 4 months.
• Aplastic crises may occur in patients with chronic haemolytic anaemia e.g. sickle cell disease. There is a sudden fall in haemoglobin which may last 5-7 days due to a lack of red cell precursors (reticulocyte count will be low). The patient will present with symptoms of anaemia.
• Chronic anaemia may occur in immunocompromised patients who have failed to produce neutralising antibodies and have chronic parvovirus infection. The anaemia resolves after administration of Normal Human Immunoglobulin (NHIG) and these patients may develop a rash illness subsequently, due to the deposition of immune complexes.
• There is no evidence that parvovirus causes birth defects. However, foetal hydrops may occur due to 2nd or 3rd trimester infection and may occur from 2-12 weeks after the rash. For this reason women who have had parvovirus infection in pregnancy should be monitored closely to assess the development of hydrops in the foetus. Such babies may require foetal exchange transfusions. Termination is not advised if there is no evidence of hydrops and the pregnancy is proceeding normally but specialist advice should be sought. Miscarriage has been reported in the first trimester following contact with B19.

Diagnosis is usually clinical but if necessary a clotted blood sample can be sent for the detection of parvovirus specific IgM (indicating current infection) and IgG (indicating previous/current infection). Ideally a blood sample should also be sent from the index case to confirm parvovirus infection. In the case of immunocompromised patients the virus can be detected using PCR to detect viral DNA in the serum.

B19 can also cause the Purpuric Glove and Stocking eruption in adults.

Slapped cheek