Makindo Medical Notes.com

Erythrovirus B19 causes Fifth’s disease and specifically infects erythroid progenitor cells, resulting in transient erythroid hypoplasia and failure of red cell production

About

• Renamed Human erythrovirus 19
• Small single stranded non-enveloped DNA
• Infects erythroid line cells
• Transmission is airborne

Aetiology

• Erythrovirus B19 only infect cells with P antigen
• These are only found on certain cells such as in the erythroid line
• Rare individuals who lack P antigen are resistant to infection with parvovirus
• If rubella is suspected in a pregnant woman, confirmation is provided either by rubella IgM antibodies in serum or by IgG seroconversion. In the exposed pregnant woman, the absence of rubella IgG indicates potential for infection. Children should be immunised against rubella as part of standard vaccination programmes using MMR (see above). Women of child-bearing age should be tested and vaccinated if seronegative Parvovirus B19 is a small (26 nm), non-enveloped, ssDNA (5.6-kb) virus
• Virus replicates in E-CFU and E-BFU of the bone marrow
• Leads to a fall in red cells, white cells and platelets
• Severe anaemia in those with pre-existing Haemolytic anaemias

Clinical

• Aplastic anaemia - anaemia, thrombocytopenia, lymphopenia
• Pregnancy: fetal anaemia, spontaneous abortion, and hydrops fetalis.
• Erythema infectiosum with a "slapped cheek" appearance
• Acute arthritis/arthralgia
• Transient aplastic crisis in those with haemolytic anaemia
• Chronic anaemia in immunodeficient patients e.g. HIV, ALL

Complications

• Fifth disease/slapped cheek appearance - tends to affect infants. Minor constitutional upset
• Gloves and socks syndrome - purpuric rash in adolescents
• Arthritis/arthralgia - adults with small joint arthropathies. Rarely children with asymmetrical large joint disease
• Red cell aplasia - mild anaemia but in can cause an aplastic crisis in those with haematological disease and shortened RBC half life.
• Hydrops fetalis - fetal aplastic crisis which can lead to spontaneous abortion

Investigations

• Reduced Hb, WCC, Platelets with reduced reticulocytes
• Erythrovirus detected in serum by PCR

Management

• May cause a sudden profound anaemia in those with a chronic haemolytic anaemia. Needs urgent blood transfusion.
• Self limiting, analgesia for arthritis
• Immunoglobulin may be given to pregnant non-immune women
• Fetal transfusion for hydrops fetalis

References

• Erythrovirus B19 infection