The mortality due to hepatocellular carcinoma (HCC) has ranged widely in various areas of Japan since 30 years ago.
Incidence was particularly high in once Schistosoma japonicum (Sj)-endemic areas.
Dr Mizokamia and colleagues from Japan undertook a study in order to estimate the spread time of hepatitis C virus (HCV) infection in the past with possible relevance to a higher incidence of HCC in once Sj-endemic than Sj-nonendemic areas.
During 2001, the investigators obtained 131 strains of HCV-1b from patients in 3 previously Sj-endemic areas, as well as Sj-nonendemic areas in Japan.
The researchers conducted a cross-sectional study on them using molecular evolutionary analyses.
| A high incidence of HCC in Sj-endemic areas would be attributed to a long duration of HCV infection since 1920s|
|Journal of Hepatology|
The research team used a phylogenetic tree reconstructed on HCV-1b sequences in the NS5B region to disclose 2 independent clusters for Sj-positive and -negative groups with a high bootstrap value.
The estimated effective number of HCV-infections indicated a transition from quiescence to rapid exponential growth in the 1920s among patients with schistosomiasis.
The researchers found this to be 20 years earlier than among patients without schistosomiasis.
Dr Mizokamia concluded, "The estimated spread time in previously Sj-endemic areas in Japan coincides with injection treatment for Sj since 1921."
"A high incidence of HCC there would be attributed to a long duration of HCV infection since 1920s."