Hepatitis C virus
- epidemiology
- classification and characteristics
- transmission and infection
- pathogenicity and virulence
- clinical manifestations
- diagnosis
- treatment
Epidemiology
- worldwide prevalence of 20o million
- most common blood-borne infection in US
- approximately 15,000 cases yearly in Canada
- 0.5-1% baseline prevalence; 65-80% of IVDU users
- 10-70% of people with ESRD
- prison population also have very high levels
Classification and Characteristics
- small enveloped RNA virus
Transmission and Infection
- usually blood-borne: IVDUs, needlesticks, transfusion
- risk of needlestick transmission: 2-5%
- risk from sexual transmission: 1-11% per year
The risk of vertical transmission is 4-7%, higher if mother is co-infected with HIV.
Pathogenicity and Virulence
Clinical Manifesations
HCV has a 2-26 week incubation period (avg 6-7 weeks), with mild-flulike symptoms. Most people are not diagnosed with acute HCV.
chronic disease in 40-70%; perhaps 15% of people clear the virus
- 30-40% asymptomatic
- 20-30% develop jaundice
- 20% may develop cirrhosis
- hepatoma is a possible long term outcome, risk increased with HIV infection or EtOH
- cryoglobulinemia: skin (esp legs), kidney, lung, lymphoma
- fine, sandpaper, spotty rash
- glomerulonephritis or nephrotic syndrome
The disease can progress faster in males, with increased alcohol intake, age over 40 years at the time of infection, HIV or HBV co-infection.
Diagnosis
- anti-HCV Abs remain elevated for life
- chronic disease monitored using liver function tests
- EIA, qPCR, RIBA also used to confirm infection: need two positives
- EIA used as screening test; PCR confirms; RIBA used to detect low levels of infection
- immunosuppressed patients may require PCR directly, as they migh not have Abs for EIA
Treatment
Prevention is key: screening of transfused blood and organs.
No vaccine; none in development due to rapidly mutation of virus. Immunoglobulin for post-exposure prophylaxis is not available for the same reason.
- stop fibrosis
- treated with pegylated interferon alpha for 20-40 weeks
- treatment leads to fever, chills, rigors, myalgia, pain, depression in 30-50%, injection site reaction, leukopenia, thrombocytopenia, autoimmune thyroiditis
- ribavarin can also be used in combination with PEG-interferon
Can eradicate the virus with some treatment