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Hepatitis C is a blood-borne, infectious, viral disease that is caused by a hepatotropic virus called Hepatitis C virus (HCV). The infection can cause liver inflammation that is often asymptomatic, but ensuing chronic hepatitis can result later in cirrhosis and liver cancer.

The hepatitis C virus (HCV) is spread by blood-to-blood contact with an infected person's blood. Many people with HCV infection have no symptoms and are unaware of the need to seek treatment. An estimated 150-200 million people worldwide are infected with hepatitis C. It is the leading cause of liver transplant in the United States.

History

In the mid 1970’s, Harvey J. Alter, Chief of the Infectious Disease Section in the Department of Transfusion Medicine at the National Institutes of Health (NIH), and his research team demonstrated that most post-transfusion hepatitis cases were not due to hepatitis A and B viruses. Despite this discovery, international research effort to identify the virus, initially called non-A, non-B hepatitis (NANBH), failed for the next decade. In 1987, Michael Houghton, Qui-Lim Choo, and George Kuo at Chiron Corporation utilized molecular cloning to identify the unknown organism. In 1988, the virus was confirmed by Alter by verifying its presence in a panel of NANBH specimens. In April of 1989, the discovery of the virus, re-named hepatitis C virus, was published in two articles in the journal Science.^[1]^[2]^[3]^[4]

Signs and symptoms

Acute Hepatitis C

Acute hepatitis C refers to the first 6 months after infection with HCV. Remarkably, 60% to 70% of people infected develop no symptoms during the acute phase. In the minority of patients who experience acute phase symptoms, they are generally mild and nonspecific, and rarely lead to a specific diagnosis of hepatitis C. Symptoms of acute hepatitis C infection include decreased appetite, fatigue, abdominal pain, jaundice, itching, and flu-like symptoms.

The hepatitis C virus is usually detectable in the blood within one to three weeks after infection, and antibodies to the virus are generally detectable within 3 to 12 weeks. Approximately 20-30% of persons infected with HCV clear the virus from their bodies during the acute phase as shown by AlAT/AspAT normalization and plasma HCV-RNA clearance (this is known as spontaneous viral clearance). The remaining 70-80% of patients infected with HCV develop chronic hepatitis C, i.e., infection lasting more than 6 months.

Previous practice was to not treat acute infections to see if the person would spontaneously clear; recent studies have shown that treatment during the acute phase of genotype 1 infections has a greater than 90% success rate with half the treatment time required for chronic infections, but that the majority of acute hepatitis C is cleared. ^[6]

Chronic Hepatitis C

Chronic hepatitis C is defined as infection with the hepatitis C virus persisting for more than six months. Clinically, it is often asymptomatic (without jaundice) and it mostly discovered accidentally.

The natural course of chronic hepatitis C varies considerably from one person to another. Virtually all people infected with HCV have evidence of inflammation on liver biopsy, however, the rate of progression of liver scarring (fibrosis) shows significant variability among individuals. Recent data suggests that among untreated patients, roughly one-third progress to liver cirrhosis in less than 20 years. Another third progress to cirrhosis within 30 years. The remainder of patients appear to progress so slowly that they are unlikely to develop cirrhosis within their lifetimes. Factors that have been reported to influence the rate of HCV disease progression include age (increasing age associated with more rapid progression), gender (males have more rapid disease progression than females), alcohol consumption (associated with an increased rate of disease progression), HIV coinfection (associated with a markedly increased rate of disease progression), and fatty liver (the presence of fat in liver cells has been associated with an increased rate of disease progression).

Symptoms specifically suggestive of liver disease are typically absent until substantial scarring of the liver has occurred. However, hepatitis C is a systemic disease and patients may experience a wide spectrum of clinical manifestations ranging from an absence of symptoms to debilitating illness prior to the development of advanced liver disease. Generalized signs and symptoms associated with chronic hepatitis C include fatigue, flu-like symptoms, muscle pain, joint pain, intermittent low-grade fevers, itching, sleep disturbances, abdominal pain (especially in the right upper quadrant), appetite changes, nausea, dyspepsia, cognitive changes, depression, headaches, and mood swings.

Once chronic hepatitis C has progressed to cirrhosis, signs and symptoms may appear that are generally caused by either decreased liver function or increased pressure in the liver circulation, a condition known as portal hypertension. Possible signs and symptoms of liver cirrhosis include ascites (accumulation of fluid in the abdomen), bruising and bleeding tendency, bone pain, varices (enlarged veins, especially in the stomach and esophagus), fatty stools (steatorrhea), jaundice, and a syndrome of cognitive impairment known as hepatic encephalopathy.

Liver function tests show variable elevation of ALAT, AST and GGTP and periodically they might show normal results. Usually prothrombin and albumin results are normal.

Chronic hepatitis C more than other forms of hepatitis is diagnosed because of extrahepatic manifestations associated with the presence of HCV such as thyroiditis (inflammation of the thyroid) with hyperthyreosis or hypothyreosis, porphyria cutanea tarda, cryoglobulinemia (a form of vasculitis)^[7] and glomerulonephritis (inflammation of the kidney), specifically membranoproliferative glomerulonephritis (MPGN)^[8]. Hepatitis C is also associated with sicca syndrome, thrombocytopenia, lichen planus, diabetes mellitus and with B-cell lymphoproliferative disorders.^[9]

Diagnosis

The diagnosis of hepatitis C is rarely made during the acute phase of the disease because the majority of people infected experience no symptoms during this phase of the disease. Those who do experience acute phase symptoms are rarely ill enough to seek medical attention. The diagnosis of chronic phase hepatitis C is also challenging due to the absence or lack of specificity of symptoms until advanced liver disease develops, which may not occur until decades into the disease.

Chronic hepatitis C may be suspected on the basis of the medical history, unexplained symptoms, or abnormal liver enzymes or liver function tests found during routine blood testing. Occasionally, hepatitis C is diagnosed as a result of targeted screening such as blood donation (blood donors are screened for numerous blood-borne diseases including hepatitis C) or contact tracing.

Hepatitis C testing begins with serological blood tests used to detect antibodies to HCV. Anti-HCV antibodies can be detected in 80% of patients within 15 weeks after exposure, in >90% within 5 months after exposure, and in >97% by 6 months after exposure. Overall, HCV antibody tests have a strong positive predictive value for exposure to the hepatitis C virus, but may miss patients who have not yet developed antibodies (seroconversion), or have an insufficient level of antibodies to detect. While uncommon, it is important to note that a small minority of people infected with HCV never develop antibodies to the virus and therefore, never test positive using HCV antibody screening.

Anti-HCV antibodies indicate exposure to the virus, but cannot determine if ongoing infection is present. All persons with positive anti-HCV antibody tests must undergo additional testing for the presence of the hepatitis C virus itself to determine whether current infection is present. The presence of the virus is tested for using molecular nucleic acid testing methods such as polymerase chain reaction (PCR), transcription mediated amplification (TMA), or branched DNA (b-DNA). All HCV nucleic acid molecular tests have the capacity to detect not only whether the virus is present, but also to measure the amount of virus present in the blood (the HCV viral load). The HCV viral load is an important factor in determining the probability of response to interferon-base therapy, but does not indicate disease severity nor the likelihood of disease progression.

In people with confirmed HCV infection, genotype testing is generally recommended. There are six major genotypes of the hepatitis C virus, which are indicated numerically (e.g., genotype 1, genotype 2, etc.). HCV genotype testing is used to determine the required length and potential response to interferon-based therapy.

Virology

The Hepatitis C virus (HCV) is a small (50 nm in size), enveloped, single-stranded, positive sense RNA virus in the family Flaviviridae. Read more in Hepatitis C virus article.

Transmission

The hepatitis C virus (HCV) is transmitted by blood-to-blood contact. In developed countries, it is estimated that 90% of persons with chronic HCV infection were infected through transfusion of unscreened blood or blood products or via injecting drug use. In developing countries, the primary sources of HCV infection are unsterilized injection equipment and infusion of inadequately screened blood and blood products.

Although injection drug use and receipt of infected blood/blood products are the most common routes of HCV infection, any practice, activity, or situation that involves blood-to-blood exposure can potentially be a source of HCV infection.

Potential sources of exposure

Several activities and practices have been identified as potential sources of exposure to the hepatitis C virus. Anyone who may have been exposed to HCV through one or more of these routes should be screened for hepatitis C.

Those who currently or have previously injected drugs are at increased risk for getting hepatitis C because they may be sharing needles or other drug paraphernalia (includes cookers, cotton, spoons, water, etc.), which may be contaminated with HCV-infected blood. An estimated 60% to 80% of all IV drug users in the United States have been infected with HCV. HCV is also transmitted by inhalational drugs, such as intranasal cocaine usage. Harm reduction strategies are encouraged in many countries to reduce the spread of hepatitis C, through education, provision of clean needles and syringes, and safer injecting techniques.

Researchers have suggested that the transimssion of HCV may be possible through the insuffulation of illegal drugs such as cocaine and crank when straws are shared among users.^[10]

Blood transfusion, blood products, or organ transplantation prior to implementation of HCV screening (in the U.S., this would refer to procedures prior to 1992) is a decreasing risk factor for hepatitis C.

The virus was first isolated in 1989 and reliable tests to screen for the virus were not available until 1992. Therefore, those who received blood or blood products prior to the implementation of screening the blood supply for HCV may have been exposed to the virus. Blood products include clotting factors (taken by hemophiliacs), immuneglobulin, Rhogam, platelets, and plasma. As of 2001, the Centers for Disease Control and Prevention reports that the risk of HCV infection from a unit of transfused blood in the United States is less than one per million transfused units.

People can be exposed to HCV via inadequately or improperly sterilized medical or dental equipment. Examples include equipment that may harbor contaminated blood if improperly sterilized include reused needles or syringes, hemodialysis equipment, oral hygiene instruments, and jet air guns, etc. Scrupulous use of appropriate sterilization techniques and proper disposal of used equipment can bring the risk of iatrogenic exposure to HCV to virtually zero.

Medical and dental personnel, first responders (e.g., firefighters, paramedics, emergency medical technicians, law enforcement officers), and military combat personnel can be exposed to HCV through accidental exposure to blood through accidental needlesticks or blood spatter to the eyes. Universal precautions to protect against such accidental exposures significantly reduce the risk of exposure to HCV.

Contact sports and other activities that may result in accidental blood-to-blood exposure are potential sources of exposure to HCV.

Although HCV is not a sexually transmitted disease (STD), transmission can occur during unprotected sexual contact if the sexual activity involves blood-to-blood contact. It is important to note that the sexual spread of HCV is due to blood-blood contact rather than the presence of the virus in vaginal fluid or semen.

Tattooing dyes, ink pots, stylets and piercing implements can transmit HCV-infected blood from one person to another if proper sterilization techniques are not followed. Tattoos or piercings done non-professionally are particularly concerning as sterile techniques in such settings may be lacking.

Personal care items such as razors, toothbrushes, cuticle scissors, and other manicuring or pedicuring equipment can easily be contaminated with blood. Sharing such items can potentially lead to exposure to HCV.

HCV is not spread through casual contact such as hugging, kissing, or sharing eating or cooking utensils.

Vertical transmission

Vertical transmission refers to the transmission of a communicable disease from an infected mother to her child during the birth process. Mother-to-child transmission of hepatitis C has been well described, but occurs relatively infrequently. Transmission occurs only among women who are HCV RNA positive at the time of delivery; the risk of transmission in this setting is approximately 6 out of 100. Among women who are both HCV and HIV positive at the time of delivery, the risk of HCV is increased to approximately 25 out of 100.

The risk of vertical transmission of HCV does not appear to be associated with method of delivery or breast feeding.

Epidemiology

Hepatitis C infects an estimated 170 million people worldwide and 4 million in the United States. There are about 35,000 to 185,000 new cases a year in the United States. Co-infection with HIV is common and rates among HIV positive populations are higher. 10,000-20,000 deaths a year in the United States are from HCV; expectations are that this will increase, as those who were infected by transfusion before HCV testing are expected to become apparent. A survey conducted in California showed prevalence of up to 34% among prison inmates;^[11] 82% of subjects diagnosed with hepatitis C have previously been in jail,^[12] and transmission while in prison is well described.^[13]

Egypt has the highest seroprevalence for HCV, up to 20% in some areas. This was linked, in 2000, to a mass-treatment campaign for schistosomiasis, which is endemic in that country.^[14]

Co-infection with HIV

Approximately 350,000, or 35% of patients in the USA infected with HIV are also infected with the hepatitis C virus, mainly because both viruses are blood-borne and present in similar populations. In other countries, co-infection is less common, this is possibly related to differing drug policies. HCV is the leading cause of chronic liver disease in the USA. It has been demonstrated in clinical studies that HIV infection causes a more rapid progression of chronic hepatitis C to cirrhosis and liver failure. This is not to say treatment is not an option for those living with co-infection.

Treatment and prognosis

There is a very small chance of clearing the virus spontaneously (0.5 to 0.74% per year),^[15]^[16] and the majority of patients with chronic hepatitis C will not clear it without treatment.

Current treatment is a combination of (pegylated) interferon alpha and the antiviral drug ribavirin for a period of 24 or 48 weeks, depending on genotype. Indications for treatment include patients with proven hepatitis C virus infection and persistent abnormal liver function tests. Sustained cure rates (sustained viral response) of 75% or better occur in people with genotypes HCV 2 and 3 in 24 weeks of treatment, about 50% in those with genotype 1 with 48 weeks of treatment and 65% for those with genotype 4 in 48 weeks of treatment. About 80% of hepatitis C patients in the United State have genotype 1. Genotype 4 is more common in the Middle East and Africa. Should treatment with pegylated ribivirin-interferon not return a 2-log viral reduction or complete clearance of RNA (termed early virological response) after 12 weeks for genotype 1, the chance of treatment success is less than 1%. Early virological response is typically not tested for in non-genotype 1 patients, as the chances of attaining it are greater than 90%.

Treatment during the acute infection phase has much higher success rates (greater than 90%) with a shorter duration of treatment (but balance this against the 80% chance of spontaneous clearance without treatment).

Those with low initial viral loads respond much better to treatment than those with higher viral loads (greater than 2 million virons/ml). Current combination therapy is usually supervised by physicians in the fields of gastroenterology, hepatology or infectious disease.

The treatment may be physically demanding, particularly those with a prior history of drug or alcohol abuse. It can qualify for temporary disability in some cases. A substantial proportion of patients will experience a panoply of side effects ranging from a 'flu-like' syndrome (the most common, experienced for a few days after the weekly injection of interferon) to severe adverse events including anemia, cardiovascular events and psychiatric problems such as suicide or suicidal ideation. The latter are exacerbated by the general physiological stress experienced by the patient.

In addition to the standard treatment with interferon and ribavirin, several studies have shown higher success rates when the antiviral drug amantadine (Symmetrel) is added to the regimen. Sometimes called "triple therapy", it involves the addition of 100mg of amantadine twice a day. Studies indicate that this may be especially helpful for "nonresponders" - patients who have not been successful in previous treatments using interferon and ribavirin only.^[17] Currently, amantadine is not approved for treatment of Hepatitis C, and studies are ongoing to determine when it is most likely to benefit the patient.

Current guidelines strongly recommend that hepatitis C patients be vaccinated for hepatitis A and B if they have not yet been exposed to these viruses, as this would radically worsen their liver disease.

Alcoholic beverage consumption accelerates HCV associated fibrosis and cirrhosis, and makes liver cancer more likely; insulin resistance and metabolic syndrome may similarly worsen the hepatic prognosis.

During pregnancy and breastfeeding

If a pregnant woman has risk factors for hepatitis C, she should be tested for anti-HCV. About four out of every hundred infants born to HCV infected women become infected. The virus is spread to the baby at the time of birth. There is no treatment that can prevent this from happening. In a mother that also has HIV, the rate of transmission can be as high as 19%. There are currently no data to determine whether antiviral therapy reduces perinatal transmission. Ribavirin and interferons are contraindicated during pregnancy. However, avoiding fetal scalp monitoring and prolonged labor after rupture of membranes may reduce the risk of transmission to the infant.

Anti-HCV from the mother might last in the baby until 15 months of age. If an early diagnosis is desired, HCV RNA can be performed between the ages of 2 and 6 months, with a repeat test done independent of the first test result. If a later diagnosis is preferred, an anti-HCV test can performed after 15 months of age. Most infants infected with HCV at the time of birth have no symptoms and do well during childhood. There is no evidence that breast-feeding spreads HCV. To be cautious, an infected mother could avoid breastfeeding if her nipples are cracked and bleeding.^[18]

Alternative therapies

Several "alternative therapies" purport to reduce the liver's duties, rather than treat the virus itself, thereby slowing the course of the disease or keeping the quality of life of the person. As an example, extract of Silybum marianum and licorice are sold for their HCV related effects; the first is said to provide some generic help to hepatic functions, and the second to have a mild antiviral effect and to raise blood pressure. It is important to note that the current standard of treatment with pegylated-interferon and ribavirin is unsurpassed in its ability to control HCV replication.

Doctors recommend reporting all medications one is taking, including herbal ones, as all may influence the disease course, and this holds true especially in post-transplants as Silybum marianum (also known as silymarin or milkthistle) may inhibit the metabolism of certain medications, leading to accumulation and increased toxicity.

Experimental treatments

The drug viramidine, which is a prodrug of ribavirin which has better targeting for the liver, and therefore may be more effective against hepatitis C for a given tolerated dose, is in phase III experimental trials against hepatitis C. It will be used in conjunction with interferon, in the same manner as ribavirin. However, this drug is not expected to be active against ribavirin-resistant strains, and the use of the drug against infections which have already failed ribavirin/interferon treatment, is unproven.

There are new drugs under development like the protease inhibitors (including VX 950) and polymerase inhibitors (such as NM 283), but development of these is still in the early phase.^[19]^[20] One protease inhibitor, BILN 2061, had to be discontinued due to safety problems early in the clinical testing. Some more modern new drugs that provide some support in treating HCV are Albuferon, Zadaxin, and DAPY. Antisense phosphorothioate oligos have been targeted to hepatitis C^[21]. Antisense Morpholino oligos have shown promise in preclinical studies and began human clinical trials in 2005 at Veterans Affairs Palo Alto Health Care System, Palo Alto, California and Alpine Clinical Research Center, Inc., Boulder, Colorado.^[22] All of these are not approved remedies and have not yet demonstrated their efficacy in clinical trials. Immunoglobulins against the hepatitis C virus exist and newer types are under development. Thus far, their roles have been unclear as they have not been shown to help in clearing chronic infection or in the prevention of infection with acute exposures (e.g. needlesticks). They do have a limited role in transplant patients.

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