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Shifting Seroepidemiology of Hepatitis A in Japan, 1973–2003
Author(s) -
Kiyohara Tomoko,
Sato Tomoko,
Totsuka Atsuko,
Miyamura Tatsuo,
Ito Toshihiro,
Yoneyama Tetsuo
Publication year - 2007
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2007.tb03900.x
Subject(s) - seroprevalence , hepatitis a , incidence (geometry) , transmission (telecommunications) , immunology , medicine , population , epidemiology , antibody , hepatitis a virus , demography , biology , serology , hepatitis , environmental health , virus , physics , electrical engineering , sociology , optics , engineering
Background . Hepatitis A infection is caused by hepatitis A virus (HAV) contracted through fecal‐oral transmission. Life‐long immunity is conferred after infection. Improved sanitary conditions have generally resulted in a significant decline in the incidence of hepatitis A. However, a low incidence of infection results in increased HAV susceptibility. The present study investigates the prevalence of anti‐HAV antibody and clarifies the current HAV status and HAV susceptibility in Japan at 2003. Methods . A total of 2,430 serum specimens collected during 2003 from Japanese individuals ranging in age from 0–92 years, were tested for anti‐HAV antibody using an inhibition enzyme linked immunosorbent assay. All specimens were obtained from the WHO and the National Serum Reference Bank/National Institute of Infectious Diseases, Tokyo, Japan. Results . The overall seroprevalence was 12.2%. Anti‐HAV antibodies were rarely detected in individuals between 0–44 years of age. Starting from the age of 45–49 years, seropositivity gradually increased through age 65 years and above. Seroprevalence was not affected by gender, and geographic distribution did not affect age‐specific seroprevalence until the age of 60 years. Conclusions . HAV susceptibility in Japan is increasing annually. Particularly, the prevalence of anti‐HAV antibody in individuals older than 50 years in 2003 was 50.3%, which is significantly lower than that of corresponding studies in 1994 (74.3%), 1984 (96.9%) and 1973 (96.9%). The growing susceptible population of advanced age results in more frequent HAV infection among them. The surveillance of anti‐HAV antibody prevalence is useful for implementing preventive measures and for controlling the spread of HAV.