Methods: To investigate the source of HPeV3 infection and the role of asymptomatic children in the families of infected children, 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.
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. Cough and/or rhinorrhea were more frequent in children (14/22, 64%) than in adults (2/8, 25%) (P = 0.101). Fever was more frequent in adults (6/8, 75%) than in children (9/22, 41%) (P = 0.215). Stool samples from symptomatic and asymptomatic siblings/cousins of 4 HPeV3-infected patients yielded positive results for HPeVs on PCR analysis. Furthermore, VP1 nucleotide sequences of family members were 100% identical to those of the respective index cases; thus, asymptomatic family members were the probable source of infection.
Conclusion: 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.
K. Watanabe, None
T. Oishi, None
A. Saitoh, None