Hepatitis C Virus

Single, positive-stranded RNA virus of approximately 10,000 nucleotides
Small (less than 50 nanometers in diameter); lipid-enveloped virus
Member of the Flaviviridae family

Routes of Transmission

HCV is a blood-borne virus. There are no known cases of HCV transmitted enterically (oral-fecal) through breast milk, semen, or saliva. The following routes of transmission are well-documented:

Percutaneous

Contaminated needlestick (injecting drug use and occupational exposure)
Hemodialysis
Human bite
Transplant or transfusion of unscreened blood or blood products
Acupuncture, tattooing, and body-piercing with unsterilized needles

Permucosal

Sexual intercourse
Perinatal – infant born to HCV infected mother
Contact with infected household objects (i.e., toothbrush or razor that may have blood on it)

Individuals at Risk

Injecting drug users
Persons occupationally exposed to blood
Hemodialysis patients
Transfusion and transplant recipients (prior to 1992)

Incidence/Prevalence

Because acute infection is asymptomatic in most cases, incidence data on a global scale is not well known. It is important to note that since the availability of multi-antigen testing in 1992, the incidence of post-transfusion HCV has declined significantly. The risk is now less than 1 in 1,000,000 units transfused.¹

In the U.S., the annual number of newly acquired acute HCV infections has declined from an estimated 240,000 in the mid-1980s to about 25,000 in 20011
In terms of prevalence, an estimated 3.9 million Americans (1.8 percent) have been infected with the virus (2.7 million chronically infected)¹
WHO estimates that up to 3.0 percent of the world’s population has been infected with HCV
Worldwide, there may be more than 170 million chronic carriers of HCV

CDC Hepatitis Information

Global Distribution of Hepatitis C, 2001²
HCV

Serologic Pattern of Acute HCV Infection With Progression to Chronic Infection³
HCV

Diagnostic Testing for Hepatitis C

HCV is diagnosed serologically by detecting antibodies specific to the hepatitis C virus (anti-HCV), and active infection is confirmed and monitored by measurements of HCV virus levels.There are limitations on using any anti-HCV assay alone to diagnose or monitor a case of hepatitis. Retesting for anti-HCV may be necessary if the initial result is negative, but clinical signs and symptoms suggest a HCV infection. Furthermore, anti-HCV does not distinguish between an acute, chronic or resolved infection. A supplemental test, RIBA (recombinant immunoblot assay), can also be used to confirm a positive anti-HCV result.⁴

Nevertheless, as a screening assay for the blood supply, current anti-HCV assays have been very effective in the U.S. at reducing post-transfusion hepatitis to a very low level.

Abbott Diagnostics has a broad offering of Hepatitis C testing on the ARCHITECT i2000/i2000SR, and AxSYM.

Developments in HCV Testing

Researchers have developed assays that detect and accurately measure HCV RNA. These assays detect the viral genome and measure the level of circulating virus in an infected individual. The level of HCV RNA in the blood is often referred to as the “viral load.” Several polymerase chain (PCR) tests for HCV RNA are now available.⁵
Applications for hepatitis C virus RNA assays include:⁵

Directly assess circulating virus in an infected individual
Evaluate suspect HCV infection before seroconversion occurs
Assess viral load before antiviral therapy is administered (patients with low, pretreatment viral load are more likely to respond; however, a high HCV RNA should not preclude treatment)⁵
Monitor the effectiveness of antiviral therapy (interferon and ribavirin)
Detect HCV infection in cases with ambiguous serology

Prevention/Prophylaxis

There is currently no vaccine for HCV. The difficulty in developing a vaccine is due, in part, to the mutability of the HCV genome. In addition, there is no effective, short-term prevention such as HBIG or immune globulin. In the absence of the above, all precautions to prevent HCV infection must be taken.

WHO recommendations on measures to prevent HCV include:

Screening of blood and blood products
Destruction of disposable needles and adequate sterilization of reusable material such as surgical or dental instruments
Effective use of universal precautions and barrier techniques (such as use of sterile equipment, the wearing of gloves, and wearing eye/face protection)
Education about the risks of using unsterilized material and high-risk drug and sexual behaviors

Additional information on HCV

References

Viral Hepatitis C Fact Sheet. Available at CDC Web site, http://www.cdc.gov/ncidod/diseases/hepatitis/c/fact.htm. Updated Oct. 1, 2003.
Global Distribution of Hepatitis A, B, and C, 2001. Wkly Epidemiol Rec. 2002; vol. 77, No. 6: 41-48.Available at Web site, http://www.who.int/wer.
Epidemiology and Prevention of Viral Hepatitis A to E: An Overview. Slide Presentation and Technical notes to accompany slide presentation from the Hepatitis Branch, Centers for Disease Control and Prevention. Updated May 16, 2003; Hepatitis A updated July 9, 2003. Available at Web site, http://www.cdc.gov/ncidod/diseases/hepatitis/slideset/index.htm (html format). Ref 3: Introduction, ref 3A: Hepatitis A, ref 3B: Hepatitis B, ref 3C: Hepatitis C, ref 3D: Hepatitis D, and ref 3E: Hepatitis E section of CDC slide/technical notes presentation.
Viral Hepatitis C: Frequently Asked Questions. Available at CDC Web site,
http://www.cdc.gov/ncidod/diseases/hepatitis/c/faq.htm. Updated Oct. 1, 2003.
Management of Hepatitis C: 2002. NIH Consens State Sci Statements. 2002 Jun. 10-12; 19(3)1-46.