Parvovirus B19 (5th disease): an unusual epidemic in progress

Human parvovirus B19 causes an infection that is most often asymptomatic but also causes erythema infectiosum, epidemic megalerythema or fifth disease, especially in children. This is an exclusively human virus transmitted by the respiratory route. Incubation lasts on average 14 days. Exanthema begins on the face, with puffy cheeks characteristically (Fig. 1), after which after 24 hours a rash appears on the torso with crumbled edges (“garland-shaped exanthema”), sometimes combined with erythema or purpura on gloves and socks.

Regression of the rash occurs spontaneously within 10–15 days. Recurrences are possible with sun exposure, exercise, swimming or changes in temperature. The general characteristics are classically reserved.

Complications are mainly hematological, at risk of erythroblastopenic crisis or prolonged cytopenia, and fetus (in case of transmission to a pregnant woman) with risk of miscarriage and hydrops fetalis. Sometimes myocarditis or encephalitis may occur.

Expulsion from school is not recommended, but it is recommended to inform at-risk individuals (especially immunocompromised) and pregnant women about the occurrence of cluster or community cases to avoid exposure.