The pathogenesis of diseases associated with B19 virus

B19 virus infection is common in the population and is frequently asymptomatic. However, a viraemia and prompt antibody response occurs in normal individuals and this is associated with mild, non-specific respiratory tract symptoms at the time of the viraemia and/or a rash-illness a week or ten days later. Infection of red cell precursors is a regular occurrence and this leads to aplastic crisis if B19 virus infection occurs in an individual with chronic heamolytic anaemia. Fetal infection sometimes takes place if infection occurs during pregnancy and some fetuses fail to clear the infection, develop anaemia leading to heart failure and hydrops fetalis. Some immunocompromised patients also fail to clear the viraemia and this results in a persistent or relapsing anaemia.