Epidemiology

Spontaneous elimination of HCV documented in a Japanese population

Last Updated: 2003-10-02 10:00:11 -0400 (Reuters Health)

By Megan Rauscher

NEW YORK (Reuters Health) - Some chronic hepatitis C virus (HCV) carriers may spontaneously eliminate the virus, suggest findings from a long-term population-based cohort study conducted in Japan.

"The natural course of HCV infection has not been fully elucidated," Dr. Takafumi Saito from Yamagata University School of Medicine and colleagues note in the September issue of the Journal of Medical Virology.

"No one has clarified how many infected individuals spontaneously withdraw from a carrier status and thus have a reduced risk of progressive liver disease," Dr. Saito further explained in comments to Reuters Health.

To investigate, Dr. Saito and colleagues followed for an average of seven years 435 chronic HCV carriers living in an area endemic for the disease. Spontaneous elimination of serum HCV RNA was documented in 16, or 3.7%, during follow up. Thus, "the incidence of spontaneous HCV elimination in the infected general population is 0.5% per year," Dr. Saito reported.

In multivariate analysis, a low zinc sulfate turbidity test (ZTT < 11 Kunkel units) and the absence of chronic liver disease on ultrasound were significantly associated with spontaneous viral elimination in chronically HCV-infected individuals.

Three of 16 spontaneous HCV eliminators had biochemical evidence of chronic hepatitis. The neutralization of binding (NOB) antibody was detected in all three, and was associated with natural resolution of the disease.

Dr. Saito emphasized that the results are not generally applicable to other populations, "since all the subjects were Japanese living in a small local area, the routes of HCV infection were obscure, and the age distribution of HCV-infected individuals in this area was different from that in other countries."

"The most important point to be learned from this study," he said, "is that there are rare populations in which the virus is eliminated spontaneously in a self-limiting manner during the course of chronic HCV infection."

"This does not mean that hesitation in starting antiviral therapy for chronic hepatitis C patients is justified," he continued, "but it seems worthwhile to further clarify the genetic characteristics of such a population."

If there are indeed differences at the gene level between carriers who can clear the virus spontaneously and those who cannot, "this would provide valuable information for future strategies aimed at the control of HCV infection through translational studies of target genes associated with viral clearance," Dr. Saito said. "We are now focusing on such genome analysis," he added.

J Med Virol 2003;71:56-61.