In 2002, I was in a serious car accident, in an induced coma for two weeks, and in the hospital for 2 1/2 months, yet none of the tests done uncovered the virus. At the same time, I am positive that I was infected in 1999 when I shared a needle. Unless you give blood or have your blood specifically screened for such viral infections, you will not know whether you are infected or not. And how many of you ever give blood? When was the last time you gave blood at a blood drive? Can you imagine how many people became infected through blood transfusions, tattoo needles, intravenous drug use, and the like before there were proper screening and safety procedures?
Addressing a growing epidemic
The HCV Infected (the best statistics available):
Over 160 Million Worldwide
2.7 to 6 Million United States
Country Estimated 2004 total Estimated HCV Population studied
population (millions) seroprevalence (%)
China 1300 3·2 Nationally representative sample (n=68 000)
India 1087 0·9 Community-based, West Bengal (n=3579)
USA 294 1·8 Nationally representative sample (n=21 214)
Indonesia 219 2·1 Volunteer blood donors (n=7572)
Brazil 179 1·1 Volunteer blood donors (n=66 414)
Pakistan 159 4·0 Volunteer blood donors (n=103 858)
The word "hepatitis" means inflammation of the liver and also refers to a group of viral infections that affect the liver. The most common types are hepatitis A, hepatitis B, and hepatitis C. Hepatitis C is a liver infection caused by the hepatitis C virus (HCV). HCV infection is the most common chronic bloodborne infection in the United States; approximately 4-6 million persons are chronically infected. San Francisco has the highest liver cancer rate in the nation, most of which is attributed to high rates of hepatitis B and hepatitis C virus infections.
Hepatitis C virus (HCV) infection is the most common chronic bloodborne infection in the United States; approximately 3.2 million persons are chronically infected. Although HCV is not efficiently transmitted sexually, persons at risk for infection through injection drug use might seek care in STD treatment facilities, HIV counseling and testing facilities, correctional facilities, drug treatment facilities, and other public health settings where STD and HIV prevention and control services are available.
Sixty to 70% of persons newly infected with HCV typically are usually asymptomatic or have a mild clinical illness. HCV RNA can be detected in blood within 1–3 weeks after exposure. The average time from exposure to antibody to HCV (anti-HCV) seroconversion is 8–9 weeks, and anti-HCV can be detected in >97% of persons by 6 months after exposure. Chronic HCV infection develops in 70%–85% of HCV-infected persons; 60%–70% of chronically infected persons have evidence of active liver disease. The majority of infected persons might not be aware of their infection because they are not clinically ill. However, infected persons serve as a source of transmission to others and are at risk for chronic liver disease or other HCV-related chronic diseases decades after infection.
HCV is most efficiently transmitted through large or repeated percutaneous exposure to infected blood (e.g., through transfusion of blood from unscreened donors or through use of injecting drugs). Although much less frequent, occupational, perinatal, and sexual exposures also can result in transmission of HCV.
The role of sexual activity in the transmission of HCV has been controversial. Case-control studies have reported an association between acquiring HCV infection and exposure to a sex contact with HCV infection or exposure to multiple sex partners. Surveillance data also indicate that 15%–20% of persons reported with acute HCV infection have a history of sexual exposure in the absence of other risk factors. Case reports of acute HCV infection among HIV-positive MSM who deny injecting-drug use have indicated that this occurrence is frequently associated with other STDs (e.g., syphilis). In contrast, a low prevalence (1.5% on average) of HCV infection has been demonstrated in studies of long-term spouses of patients with chronic HCV infection who had no other risk factors for infection. Multiple published studies have demonstrated that the prevalence of HCV infection among MSM who have not reported a history of injecting-drug use is no higher than that of heterosexuals. Because sexual transmission of other bloodborne viruses, such as HIV, is more efficient among homosexual men than in heterosexual men and women, the reason that HCV infection rates are not substantially higher among MSM is unclear. Overall, these findings indicate that sexual transmission of HCV is possible but inefficient.
What is the incidence of HCV infection in the United States?
Although only 849 cases of confirmed acute Hepatitis C were reported in the United States in 2007, CDC estimates that approximately 17,000 new HCV infections occurred that year, after adjusting for asymptomatic infection and underreporting. Persons newly infected with HCV are usually asymptomatic, so acute Hepatitis C is rarely identified or reported.
What is the prevalence of chronic HCV infection in the United States?
Approximately 3.2 million persons in the United States have chronic HCV infection. Infection is most prevalent among those born during 1945–1965, the majority of whom were likely infected during the 1970s and 1980s when rates were highest.
Who is at risk for HCV infection?
The following persons are at known to be at increased risk for HCV infection:
- Current or former injection drug users, including those who injected only once many years ago
- Recipients of clotting factor concentrates made before 1987, when more advanced methods for manufacturing those products were developed
- Recipients of blood transfusions or solid organ transplants before July 1992, when better testing of blood donors became available
- Chronic hemodialysis patients
- Persons with known exposures to HCV, such as
- health care workers after needlesticks involving HCV-positive blood
- recipients of blood or organs from a donor who tested HCV-positive
- Persons with HIV infection
- Children born to HCV-positive mothers
Is it possible for someone to become infected with HCV and then spontaneously clear the infection?
Yes. Approximately 15%–25% of persons clear the virus from their bodies without treatment and do not develop chronic infection; the reasons for this are not well known.
How likely is HCV infection to become chronic?
HCV infection becomes chronic in approximately 75%–85% of cases.
Why do most persons remain chronically infected with HCV?
A person infected with HCV mounts an immune response to the virus, but replication of the virus during infection can result in changes that evade the immune response. This may explain how the virus establishes and maintains chronic infection.
What are the chances of someone developing chronic HCV infection, chronic liver disease, cirrhosis, or liver cancer or dying as a result of Hepatitis C?
Of every 100 persons infected with HCV, approximately
- 75–85 will go on to develop chronic infection
- 60–70 will go on to develop chronic liver disease
- 5–20 will go on to develop cirrhosis over a period of 20–30 years
- 1–5 will die from the consequences of chronic infection (liver cancer or cirrhosis)
Can persons become infected with a different strain of HCV after they have cleared the initial infection?
Yes. Prior infection with HCV does not protect against later infection with the same or different genotypes of the virus. This is because persons infected with HCV typically have an ineffective immune response due to changes in the virus during infection. For the same reason, no effective pre- or postexposure prophylaxis (i.e., immune globulin) is available.
Is Hepatitis C a common cause for liver transplantation?
Yes. Chronic HCV infection is the leading indication for liver transplants in the United States.
How many deaths can be attributed to chronic HCV infection?
Chronic HCV infection accounts for an estimated 8,000–10,000 deaths each year in the United States.
Is there a Hepatitis C vaccine?
No vaccine for Hepatitis C is available. Research into the development of a vaccine is under way.
Transmission and Symptoms
How is HCV transmitted?
HCV is transmitted primarily through large or repeated percutaneous (i.e., passage through the skin) exposures to infectious blood, such as
- Injection drug use (currently the most common means of HCV transmission in the United States)
- Receipt of donated blood, blood products, and organs (once a common means of transmission but now rare in the United States since blood screening became available in 1992)
- Needlestick injuries in health care settings
- Birth to an HCV-infected mother
HCV can also be spread infrequently through
- Sex with an HCV-infected person (an inefficient means of transmission)
- Sharing personal items contaminated with infectious blood, such as razors or toothbrushes (also inefficient vectors of transmission)
- Other health care procedures that involve invasive procedures, such as injections (usually recognized in the context of outbreaks)
What is the prevalence of HCV infection among injection drug users (IDUs)?
The most recent surveys of active IDUs indicate that approximately one third of young (aged 18–30 years) IDUs are HCV-infected. Older and former IDUs typically have a much higher prevalence (approximately 70%–90%) of HCV infection, reflecting the increased risk of continued injection drug use. The high HCV prevalence among former IDUs is largely attributable to needle sharing during the 1970s and 1980s, before the risks of bloodborne viruses were widely known and before educational initiatives were implemented.
Is cocaine use associated with HCV transmission?
There are very limited epidemiologic data to suggest an additional risk from non-injection (snorted or smoked) cocaine use, but this risk is difficult to differentiate from associated injection drug use and sex with HCV-infected partners.
What is the risk of acquiring HCV infection from transfused blood or blood products in the United States?
Now that more advanced screening tests for HCV are used in blood banks, the risk is considered to be less than 1 chance per 2 million units transfused. Before 1992, when blood screening for HCV became available, blood transfusion was a leading means of HCV transmission.
Can HCV be spread during medical or dental procedures?
As long as Standard Precautions and other infection control practices are used consistently, medical and dental procedures performed in the United States generally do not pose a risk for the spread of HCV. However, HCV has been spread in health care settings when injection equipment, such as syringes, was shared between patients or when injectable medications or intravenous solutions were mishandled and became contaminated with blood. Health care personnel should understand and adhere to Standard Precautions, which includes safe injection practices and other guidance aimed at reducing bloodborne pathogen risks for patients and health care personnel. If health care-associated HCV infection is suspected, this should be reported to state and local public health authorities.
Can HCV be spread within a household?
Yes, but this does not occur very often. If HCV is spread within a household, it is most likely a result of direct, through-the-skin exposure to the blood of an infected household member.
What are the signs and symptoms of acute HCV infection?
Persons with newly acquired HCV infection usually are asymptomatic or have mild symptoms that are unlikely to prompt a visit to a health care professional. When symptoms occur, they can include
- Fever
- Fatigue
- Dark urine
- Clay-colored stool
- Abdominal pain
- Loss of appetite
- Nausea
- Vomiting
- Joint pain
- Jaundice
What percentage of persons infected with HCV develop symptoms of acute illness?
Approximately 20%–30% of those newly infected with HCV experience fatigue, abdominal pain, poor appetite, or jaundice.
How soon after exposure to HCV do symptoms appear?
In those persons who do develop symptoms, the average time period from exposure to symptom onset is 4–12 weeks (range: 2–24 weeks).
What are the signs and symptoms of chronic HCV infection?
Most persons with chronic HCV infection are asymptomatic. However, many have chronic liver disease, which can range from mild to severe, including cirrhosis and liver cancer. Chronic liver disease in HCV-infected persons is usually insidious, progressing slowly without any signs or symptoms for several decades. In fact, HCV infection is often not recognized until asymptomatic persons are identified as HCV-positive when screened for blood donation or when elevated alanine aminotransferase (ALT, a liver enzyme) levels are detected during routine examinations.
Testing and Diagnosis
Who should be tested for HCV infection?
HCV testing is recommended for anyone at increased risk for HCV infection, including:
- Persons who have ever injected illegal drugs, including those who injected only once many years ago
- Recipients of clotting factor concentrates made before 1987
- Recipients of blood transfusions or solid organ transplants before July 1992
- Patients who have ever received long-term hemodialysis treatment
- Persons with known exposures to HCV, such as
- health care workers after needlesticks involving HCV-positive blood
- recipients of blood or organs from a donor who later tested HCV-positive
- All persons with HIV infection
- Patients with signs or symptoms of liver disease (e.g., abnormal liver enzyme tests)
- Children born to HCV-positive mothers (to avoid detecting maternal antibody, these children should not be tested before age 18 months)
What blood tests are used to detect HCV infection?
Several blood tests are performed to test for HCV infection, including:
- Screening tests for antibody to HCV (anti-HCV)
- enzyme immunoassay (EIA)
- enhanced chemiluminescence immunoassay (CIA)
- Recombinant immunoblot assay (RIBA)
- Qualitative tests to detect presence or absence of virus (HCV RNA polymerase chain reaction [PCR])
- Quantitative tests to detect amount (titer) of virus (HCV RNA PCR)
Objective: To describe the HCV-infected population in the United States.
Design: Nationally representative household survey.
Setting: U.S. civilian, noninstitutionalized population.
Participants: 15 079 participants in the National Health and Nutrition Examination Survey between 1999 and 2002.
Measurements: All participants provided medical histories, and those who were 20 to 59 years of age provided histories of drug use and sexual practices. Participants were tested for antibodies to HCV (anti-HCV) and HCV RNA, and their serum alanine aminotransferase (ALT) levels were measured.
Results: The prevalence of anti-HCV in the United States was 1.6% (95% CI, 1.3% to 1.9%), equating to an estimated 4.1 million (CI, 3.4 million to 4.9 million) anti-HCV–positive persons nationwide; 1.3% or 3.2 million (CI, 2.7 million to 3.9 million) persons had chronic HCV infection. Peak prevalence of anti-HCV (4.3%) was observed among persons 40 to 49 years of age. A total of 48.4% of anti-HCV–positive persons between 20 and 59 years of age reported a history of injection drug use, the strongest risk factor for HCV infection. Of all persons reporting such a history, 83.3% had not used injection drugs for at least 1 year before the survey. Other significant risk factors included 20 or more lifetime sex partners and blood transfusion before 1992. Abnormal serum ALT levels were found in 58.7% of HCV RNA–positive persons. Three characteristics (abnormal serum ALT level, any history of injection drug use, and history of blood transfusion before 1992) identified 85.1% of HCV RNA–positive participants between 20 and 59 years of age.
Limitations: Incarcerated and homeless persons were not included in the survey.
Conclusions: Many Americans are infected with HCV. Most were born between 1945 and 1964 and can be identified with current screening criteria. History of injection drug use is the strongest risk factor for infection.
No comments:
Post a Comment