Asymptomatic children might transmit human parechovirus type 3 to neonates and young infants.

BACKGROUND

Human parechovirus type 3 (HPeV3) epidemics occur worldwide and can lead to severe disease in neonates and young infants. Little is known about the source of HPeV3 infection.

OBJECTIVES

To investigate the source of HPeV3 infection and the role of asymptomatic children in the families of infected children.

STUDY DESIGN

During a 2014 HPeV3 epidemic in Niigata, Japan, we analyzed (1) clinical information on sick contacts for 43 neonates and young infants with HPeV3-related disease diagnosed by PCR analysis of serum and/or cerebrospinal fluid and (2) stool samples from symptomatic and asymptomatic siblings/cousins of index patients. To confirm transmission, the P1 (VP0, VP3, and VP1) and 3D(pol) regions of HPeVs were sequenced and analyzed.

RESULTS

Sick contact with family members was confirmed for 51% (n=22) of patients. Among the 30 symptomatic family members, 67% (n=20) were siblings, 20% (n=6) were mothers, and 13% (n=4) were other relatives. Stool samples from symptomatic and asymptomatic siblings/cousins of 4 HPeV3-infected patients yielded positive results for HPeVs on PCR analysis. Furthermore, the P1 and 3D(pol) nucleotide sequences of family members were 100% identical to those of the respective index cases.

CONCLUSIONS

Identification of genetically identical virus from HPeV3-infected patients and asymptomatic children in their families suggests that the latter are a source of infection in neonates and young infants with HPeV3-related diseases.