The symptoms of erythema infectiosum occurs late in the course of events, with the rash appearing 17 - 18 days after inoculation, and arthralgia a day or so later. These symptoms are likely to be immune mediated. It appears that an early erythrocyte precursor is susceptible to B19 infection. From Course BS335 Lecture Notes by Dr. Alan Cann C. Epidemiology B19 virus is present throughout the year, in temperate climates outbreaks of infection are more common in the spring and summer. Infection is commonest amongst 4 - 10 yr olds.
Respiratory spread is the usual route of transmission of the virus.
The frequency of seropositivity among haemophiliac children is significantly higher than normal. The common manifestation of B19 infection is a mild febrile illness with a maculopapular rash. In children, a slapped cheek appearance is common. In adults,this is less common but the rash is frequently followed by joint involvement. There is a period of 7 before the onset of the rash.