[Parvovirus B19 and pediatric pathology]

B 19 parvovirus is a widespread virus with primary infestation generally occurring in childhood through family and community outbreaks. Its most typical manifestation is transient erythroblastopenia with aplastic crisis, often profound, mostly affecting patients with chronic hemolytic anemia, and eventually patients with defective erythropoiesis (chronic hypoplastic anemia, iron deficiency anemia). In normal individuals the primary infestation is usually asymptomatic but may give transient hematological signs for few days: moderate reticulocytopenia, thrombopenia and neutropenia. Clinically two phases of the infection are described: 1.) a first phase of viremia of 2 to 3 days which may be accompanied by fever and myalgias; 2.) a second phase which may last for several weeks with dermatological signs, the most typical being erythema infectiosum, vasculitis, arthralgias or arthritis. In pregnant women, the primary infestation with B 19 parvovirus may lead to fetal anemia and hydrops fetalis with uneven outcomes: fetal death, chronic erythroblastopenia after birth, spontaneous resolution. Although the incidence of fetal infestation in non immunized pregnant women is still unknown, the question is raised of the recognition and protection of non immunized pregnant women at high risk of exposition to infested subjects. Long term persistence of the virus in the organism may be responsible for chronic manifestation, essentially but not exclusively in immunodeficient-patients: prolonged erythroblastopenia and chronic rheumatologic manifestations. It may be also responsible for cases of juvenile arthritis, thrombocytopenic purpura and chronic neutropenia of childhood. The diagnosis of the viral infestation is mainly based upon the detection of specific IgM, then IgG, antibodies by Elisa technique.