Seropositivity and epidemiology of human parechovirus types 1, 3, and 6 in Japan

Area of Science:

• Virology
• Epidemiology
• Pediatrics

Background:

• Human parechoviruses (HPeVs) are common viral pathogens, primarily affecting young children with gastrointestinal and respiratory symptoms.
• Human parechovirus type 3 (HPeV3) is an exception, frequently causing severe systemic illness, including sepsis, in neonates and young infants.

Purpose of the Study:

• To investigate the seropositivity and epidemiological characteristics of HPeV infections in different age groups in Niigata, Japan.
• To correlate HPeV genotypes with clinical manifestations and patient demographics.

Main Methods:

• Measurement of neutralizing antibody titers against various HPeV types in human serum samples across different age demographics.
• Isolation and identification of HPeVs from diverse clinical specimens collected from patients.

Main Results:

• Seropositivity for HPeV1, HPeV3, and HPeV6 was higher in older age groups, with HPeV1 and HPeV6 antibodies maintained in adults.
• Significantly lower HPeV3 seropositivity was observed in individuals over 40 years old, suggesting increased adult susceptibility.
• HPeV1 and HPeV6 were associated with gastroenteritis in infants and young children, while HPeV3 was exclusively isolated from neonates and young infants with severe sepsis-like illness, often with respiratory involvement.

Conclusions:

• Clinical symptoms associated with HPeV infections are strongly dependent on the specific HPeV genotype and the age of the patient.
• Adults over 40 may be more susceptible to severe HPeV3 infections due to a lack of pre-existing neutralizing antibodies.