Epidemiology

Spontaneous HCV clearance more common than previously thought

Last Updated: 2006-04-19 13:49:43 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Spontaneous clearance of hepatitis C virus (HCV) after chronic infection is thought to be a rare event, but new research suggests that clearance rates as high as 8% may occur.

Roughly 15% to 30% of people who become infected with HCV will clear the virus during the acute phase. Until recently, it was believed that the remaining patients with chronic infection seldom, if ever, clear the virus.

In a Japanese study reported in 2003, an HCV clearance rate of 3.7% was described in patients with chronic infection. The present findings, which appear in Clinical Infectious Diseases for April 1, suggest that the rate may be higher still.

The study involved 139 Alaskan natives who had tested positive for HCV RNA on three separate occasions and were followed on a regular basis for a mean period of 7 years.

Eleven of the patients (8%) had at least one test with undetectable HCV RNA during follow-up. Seven of these patients were considered to have probable or possible HCV clearance, yielding an annual clearance rate of 0.74% per person year.

Follow-up testing of nine of the seronegative patients identified five that still appeared to be virus-free, the report indicates. A low HCV RNA titer predicted spontaneous nondetectability of HCV RNA.

In a related editorial, Dr. Georg M. Lauer and Dr. Arthur Y. Kim, from Harvard Medical School in Boston, point out that "more studies are needed before we can feel confident about the incidence of spontaneous viral clearance in chronic HCV infection or before we start investigating the genetic disposition of Alaska Natives and its relevance to viral control."

"Meanwhile, clinicians should stay alert to this rare outcome of HCV infection, and further investigations of this phenomenon should be strongly encouraged," the editorialists add.

Clin Infect Dis 2006;42:945-954.