Clinical

Viral load criteria help distinguish acute from chronic HCV

Last Updated: 2009-09-29 19:19:45 -0400 (Reuters Health)

By David Douglas

NEW YORK (Reuters Health) - Viral load features can help to distinguish acute hepatitis C virus (HCV) infection from chronic infection, researchers report in the October 1st issue of Clinical Infectious Diseases.

"The diagnosis of acute hepatitis C infection is problematic," lead investigator Dr. Barbara H. McGovern told Reuters Health, "because HCV antibody does not distinguish between acute and chronic infection and seroconversion is often not documented, particularly in injection drug users."

"Use of virologic parameters that are uncommon in chronic infection," she added, "namely fluctuating viremia... and low level viremia... can help identify those who may have acute infection."

In an earlier prison-based pilot study, Dr. McGovern of Lemuel Shattuck Hospital in Jamaica Plain, Massachusetts and her colleagues found that serial monitoring of HCV RNA levels over 10 weeks could differentiate seroconverters who developed persistent viremia from those who attained spontaneous resolution.

In their pilot study, 81% of subjects with acute HCV infection had low-level viremia and 86% had viral load fluctuations. In contrast, only 13% of patients with chronic HCV had low-level viremia.

To validate these earlier findings, the researchers went on to prospectively study 35 high-risk injection drug users who were entering prison with suspected acute HCV infection. Patients with HCV RNA fluctuations >1 log were classified as being at "high probability" of acute HCV infection, as were patients with any single HCV RNA measurement above 100,000 IU/mL. Patients with fluctuations <1 log were "moderate probably" or "low probability" depending on their peak alanine aminotransferase level. Patients with spontaneous clearance were classified as "definite" acute infection.

Using standard diagnostic criteria, all received a diagnosis of acute HCV infection.

Using the novel criteria, however, "we were able to reclassify the (patients)...as having 'definite' (n=8), 'high probability' (n=20), 'moderate probability' (n=5), and 'low probability' (n=2) acute HCV infection," the investigators said.

Dr. McGovern commented to Reuters Health that "early treatment interventions can lead to sustained viral eradication," and indeed, her team writes, "the veracity" of the novel criteria "is reflected by...high sustained virologic response rates...in those who accepted therapy."

"The diagnosis of acute infection in HCV-seropositive patients is strengthened by the use of virologic parameters that are uncommon in chronic disease," the investigators conclude.

Clin Infect Dis 2009;49:1051-1060.