Acute Hepatitis C Infection and Spontaneous Viral Clearance in Adults and Children
Studies of acute hepatitis C virus (HCV) infection can be challenging,
since a majority of infected people do not experience symptoms, and thus do
not present for care and HCV testing.
Past research, including a meta-analysis published last year*, indicates
that approximately 25% of adults infected with HCV spontaneously clear the
virus without treatment (though different studies have found rates ranging
from about 10% to 50%). Spontaneous clearance rates tend to be higher among
women than men (40% vs 19% in the recent meta-analysis) and among
individuals who experience acute hepatitis C symptoms, which is thought to
signal a more robust immune response. Clearance, if it occurs, usually
happens within 4 months, but may take up to 18 months, or possibly even
Two recent studies provide further data about acute hepatitis C and
spontaneous HCV clearance in adults and children.
Acute HCV in Adults
In the first study, reported in the November 15, 2007 Journal of
Infectious Diseases, C.C. Wang and colleagues assessed acute HCV infection
in a cohort of 67 individuals enrolled at multiple U.S. clinics between 2003
and 2005. Acute infection was identified based on HCV seroconversion within
1 year of a previous test (n=45), new HCV antibody seropositivity plus
clinical hepatitis symptoms (n=21), or HCV viral sequencing after an
iatrogenic (medical) (n=1). Risk factors were assessed using a questionnaire
and participants were followed prospectively with serial HCV RNA
66% of subjects with acute HCV infection were injection drug users.
13 individuals (19%) had an unknown route of transmission.
Of these, 11 (85%) reported high-risk sexual behavior (which was defined broadly and included sex before age 15, more than 6 lifetime sexual partners, exchanging sex for money, sex with a prostitute, having a same-sex partner, and sex with an injection drug user or a person known to have HCV).
10 people developed acute infection within 3 months of exposure in a medical setting, and 3 had confirmed iatrogenic infection.
3 people had gotten a tattoo in the past year and 1 lived with an HCV positive household member.
Overall, 64% of study participants were asymptomatic.
After 6 months, 18% spontaneously cleared HCV without treatment.
The rate of spontaneous HCV clearance was 34% for women, compared with 3% for men (P < 0.001).
Based on these findings, the authors concluded that, “High-risk sexual or
iatrogenic exposures may be important contemporary risk factors for HCV
They added that, “The spontaneous viral clearance rate (18%) in this
contemporary study was similar to that reported for past studies of
transfusion-associated HCV infection.”
University of Washington, Seattle, WA; Public Health-Seattle and King
County, WA; Oregon Health Sciences University, Portland, OR; University of
Colorado Health Sciences University, Denver, CO; Mid-South Regional Blood
Center (Lifeblood), Memphis, TN; University of Pittsburgh, Pittsburgh, PA.
Spontaneous Clearance in Children
Fewer studies to date have
assessed acute HCV infection and rates of spontaneous viral clearance in
children. This is an interesting question, since in the case of acute
hepatitis B, about 95% of adults spontaneously clear the virus without
treatment, compared with only about 10% of infants infected at birth.
L.T. Yeung and colleagues assessed the rate of spontaneous HCV clearance in
157 children with hepatitis C identified between 1990 and 2001; most were
infected via transfusions. Clearance was defined as at least 2 positive HCV
antibody tests combined with undetectable HCV RNA. Results were reported in
the November 2007 Journal of Viral Hepatitis.
44 children (28%) cleared HCV without treatment.
The spontaneous clearance rate was similar in children infected via transfusions and those infected through other routes (28% vs 29%).
In general, younger age at follow-up predicted a greater likelihood of spontaneous clearance (P < 0.0001).
However, just 25% of children with neonatal infection cleared HCV after 7 years.
Normal alanine aminotransferase (ALT) predicted HCV clearance (P < 0.0001)
In contrast with adults, sex was not found to be a significant predictor of HCV clearance
“The rate of spontaneous clearance of childhood HCV infection was
comparable between transfusional and non-transfusional cases,” the study
authors concluded. “If clearance occurs, it tends to occur early in
infection, at a younger age.”
Unlike hepatitis B, spontaneous hepatitis C clearance seems to occur at
similar rates in adults and children.
Rouge Valley Health System; Division of Gastroenterology and Nutrition;
Hospital for Sick Children; Population Health Sciences; and Department of
Paediatrics, University of Toronto, Ontario, Canada.
CC Wang, E Krantz, J Klarquist, and others. Acute hepatitis C in a
contemporary US cohort: modes of acquisition and factors influencing viral
clearance. Journal of Infectious Diseases 196(10): 1474-1482. November 15,
LTF Yeung, T To, SM King, and others. Spontaneous clearance of childhood
hepatitis C virus infection. Journal of Viral Hepatitis 14(11): 797-805.
* JM Micallef, JM Kaldor, GJ Dore. Spontaneous viral clearance following
acute hepatitis C infection: a systematic review of longitudinal studies.
Journal of Viral Hepatitis 13(1): 34-41. January 2006.