* This is the Professional Version. *
Hepatitis C, Acute
Hepatitis C is caused by an RNA virus that is often parenterally transmitted. It sometimes causes typical symptoms of viral hepatitis, including anorexia, malaise, and jaundice but may be asymptomatic. Fulminant hepatitis and death rarely occur. Chronic hepatitis develops in about 75% and can lead to cirrhosis and rarely hepatocellular carcinoma. Diagnosis is by serologic testing. Treatment is supportive. No vaccine is available.
In the US, about 2000 cases of acute hepatitis C infection are reported annually. However, because many cases are not recognized or not reported, the CDC estimates that the actual number of new infections is close to 30,000 annually (see CDC Hepatitis C FAQs).
Hepatitis C virus (HCV) is a single-stranded RNA flavivirus that causes acute viral hepatitis and is a common cause of chronic viral hepatitis. Six major HCV subtypes exist with varying amino acid sequences (genotypes); these subtypes vary geographically and in virulence and response to therapy. HCV can also alter its amino acid pattern over time in an infected person, producing quasispecies.
HCV infection sometimes occurs simultaneously with specific systemic disorders, including the following:
The mechanisms are uncertain.
In addition, up to 20% of patients with alcoholic liver disease harbor HCV. The reasons for this high association are unclear because concomitant alcohol and drug use accounts for only a portion of cases. In these patients, HCV and alcohol act synergistically to worsen liver inflammation and fibrosis.
Infection is most commonly transmitted through blood, primarily when parenteral drug users share needles, but also through tattoos or body piercing.
Sexual transmission and vertical transmission from mother to infant are relatively rare.
Transmission through blood transfusion has become very rare since the advent of screening tests for donated blood.
Some sporadic cases occur in patients without apparent risk factors.
HCV prevalence varies with geography and other risk factors.
Hepatitis C may be asymptomatic during the acute infection. Its severity often fluctuates, sometimes with recrudescent hepatitis and roller-coaster aminotransferase levels for many years or even decades. Fulminant hepatitis is extremely rare.
HCV has the highest rate of chronicity (about 75%). The resultant chronic hepatitis C is usually asymptomatic or benign but progresses to cirrhosis in 20 to 30% of patients; cirrhosis often takes decades to appear. Hepatocellular carcinoma can result from HCV-induced cirrhosis but results only rarely from chronic infection without cirrhosis (unlike in hepatitis B).
In the initial diagnosis of acute hepatitis, viral hepatitis should be differentiated from other disorders causing jaundice (see Figure: Simplified diagnostic approach to possible acute viral hepatitis.). If acute viral hepatitis is suspected, the following tests are done to screen for hepatitis viruses A, B, and C:
If the anti-HCV test is positive, HCV-RNA is measured to distinguish active from past hepatitis C infection (see Table: Hepatitis C Serology).
In hepatitis C, serum anti-HCV represents chronic, past, or acute infection; the antibody is not protective. In unclear cases, HCV-RNA is measured. Anti-HCV usually appears within 2 wk of acute infection but is sometimes delayed; however, HCV-RNA is positive sooner.
No treatments attenuate acute viral hepatitis, including hepatitis C.
There are a number of new, highly effective direct-acting antiviral drugs for chronic hepatitis C that may decrease the likelihood of developing chronic infection. However, the regimens are very expensive and have not been studied in acute infection; current recommendations are to follow patients for 6 mo to allow spontaneous clearance and then treat those who have persistent viremia (ie, chronic hepatitis C).
Alcohol should be avoided because it can increase liver damage. Restrictions on diet or activity, including commonly prescribed bed rest, have no scientific basis.
Most patients may safely return to work after jaundice resolves, even if AST or ALT levels are slightly elevated.
For cholestatic hepatitis, cholestyramine 8 g po once/day or bid can relieve itching.
Viral hepatitis should be reported to the local or state health department.
Patients should be advised to avoid high-risk behavior (eg, sharing needles to inject drugs, getting tattoos and body piercings).
Blood and other body fluids (eg, saliva, semen) are considered infectious. Risk of infection after a single needlestick exposure is about 1.8%. Barrier protection is recommended, but isolation of patients is of no value in preventing acute hepatitis C.
Risk of transmission from HCV-infected medical personnel appears to be low, and there are no CDC recommendations to restrict health care workers with hepatitis C infection.
Posttransfusion infection is minimized by avoiding unnecessary transfusions and screening all donors for HBsAg and anti-HCV. Screening has decreased the incidence of posttransfusion hepatitis, probably to about 1/100,000 units of blood component transfused.
No product exists for immunoprophylaxis of HCV. The propensity of HCV for changing its genome hampers vaccine development.
Hepatitis C is usually transmitted by parenteral contact with contaminated blood; transmission from mucosal contact with other body fluids and perinatal transmission from infected mothers are rare.
About 75% of patients with acute hepatitis C develop chronic hepatitis C, which leads to cirrhosis in 20 to 30%; some patients with cirrhosis develop hepatocellular carcinoma.
Diagnose by testing for antibody to HCV and other serologic markers.
There is no vaccine for hepatitis C.
* This is the Professional Version. *