Human parechovirus 1 infections in young children--no association with type 1 diabetes.

The epidemiology, transmission and clinical symptoms of human parechoviruses [HPeV, classified earlier as enteroviruses; echovirus 22 (HPeV1) and echovirus 23 (HPeV2)] remain poorly characterized. Enteroviruses and one parechovirus species, the Ljungan virus, have been associated with type 1 diabetes in humans and rodents. The occurrence of human parechovirus 1 (HPeV1) infections in young children and their possible association with type 1 diabetes was evaluated. The prospective birth cohort study comprised 221 Finnish children carrying genetic type 1 diabetes susceptibility and who were observed from birth. Thirty-four children developed multiple diabetes-associated autoantibodies, and 18 children progressed to clinical type 1 diabetes during the follow-up. HPeV1 infections were diagnosed by measuring neutralizing antibodies from the follow-up sera taken every 3-12 months. In addition, viral RNA was analysed by RT-PCR from stool samples taken every month from six of the participants. HPeV1 infections were found to occur early in childhood. The median age of infection was 18 months and 20% of the children had had an infection by the age of 1 year. The number of infections started to increase from the age of 6 months and most children had their first infection by 36 months. Nearly all (99%) mothers were HPeV1 antibody positive. No difference was found in infection frequency between boys and girls, nor between prediabetic, diabetic and control subjects. Most infections (87%) occurred during autumn, winter and spring.