Hepatitis C is an infectious disease affecting the liver, caused by the hepatitis C virus (HCV). The infection is often asymptomatic, but once established, chronic infection can progress to scarring of the liver (fibrosis), and advanced scarring (cirrhosis) which is generally apparent after many years. In some cases, those with cirrhosis will go on to develop liver failure or other complications of cirrhosis, including liver cancer.
The hepatitis C virus (HCV) is spread by blood-to-blood contact. Most people have few symptoms after the initial infection, yet the virus persists in the liver in about 80% of those infected. Persistent infection can be treated with medication, such as interferon and ribavirin, and currently over half are cured overall. Those who develop cirrhosis or liver cancer may require a liver transplant, although the virus generally recurs after transplantation.
An estimated 150-200 million people worldwide are infected with hepatitis C. Apart from humans, it only infects chimpanzees. No vaccine against hepatitis C is available. The existence of hepatitis C (originally "non-A non-B hepatitis") was postulated in the 1970s and proved conclusively in 1989. It is one of five known hepatitis viruses: A, B, C, D, and E
Signs and symptoms:
Acute:
Acute hepatitis C refers to the first 6 months after infection with HCV. Between 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 by PCR, and antibodies to the virus are generally detectable within 3 to 15 weeks. Approximately 15-40% of persons infected with HCV clear the virus from their bodies during the acute phase as shown by normalization in liver function tests (LFTs) such as alanine transaminase (ALT) & aspartate transaminase (AST) normalization, as well as plasma HCV-RNA clearance (this is known as spontaneous viral clearance). The remaining 60-85% 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.
Virology:
Hepatitis C infection in the US by source. (CDC,n.d.[dead link])Main article: Hepatitis C virus:
The Hepatitis C virus (HCV) is a small (50 nm in size), enveloped, single-stranded, positive sense RNA virus. It is the only known member of the hepacivirus genus in the family Flaviviridae. There are six major genotypes of the hepatitis C virus, which are indicated numerically (e.g., genotype 1, genotype 2, etc.).
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 or, by inhalational drug use. In developing countries, the primary sources of HCV infection are unsterilized injection equipment and infusion of inadequately screened blood and blood products. There has not been a documented transfusion-related case of hepatitis C in the United States for over a decade as the blood supply is vigorously screened with both EIA and PCR technologies.
Although injection drug use and inhalational drugs 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. The virus may be sexually transmitted, although this is rare, and usually only occurs when an STD (like HIV) is also present and makes blood contact more likely.
Injection drug use:
Those who currently use or have used drug injection as their delivery route for illicit 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 intravenous recreational drug users in the United States have been infected with HCV. 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. For reasons that are not clear transmission by this route currently appears to be declining in the US.
Sexual exposure:
Sexual transmission of HCV is considered to be rare. Studies show the risk of sexual transmission in heterosexual, monogamous relationships is extremely rare or even null. The CDC does not recommend the use of condoms between long-term monogamous discordant couples (where one partner is positive and the other is negative).[16] However, because of the high prevalence of hepatitis C, this small risk may translate into a non-trivial number of cases transmitted by sexual routes. Vaginal penetrative sex is believed to have a lower risk of transmission than sexual practices that involve higher levels of trauma to anogenital mucosa (anal penetrative sex, fisting, use of sex toys).
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 transmitting 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 breastfeeding.
Treatment:
There is a very small chance of clearing the virus spontaneously in chronic HCV carriers (0.5 to 0.74% per year), however, the majority of patients with chronic hepatitis C will not clear it without treatment.
Current treatment is a combination of pegylated interferon alpha (brand names Pegasys and PEG-Intron) 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 States 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%. The mechanism of action is not entirely clear, because even patients who appear to have had a sustained virological response still have actively replicating virus in their liver and peripheral blood mononuclear cells.
The evidence for treatment in genotype 6 disease is currently sparse, and the evidence that exists is for 48 weeks of treatment at the same doses as are used for genotype 1 disease.[24] Physicians considering shorter durations of treatment (e.g., 24 weeks) should do so within the context of a clinical trial.
Treatment during the acute infection phase has much higher success rates (greater than 90%) with a shorter duration of treatment; however, this must be balanced against the 15-40% chance of spontaneous clearance without treatment (see Acute Hepatitis C section above).
Those with low initial viral loads respond much better to treatment than those with higher viral loads (greater than 400,000 IU/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 for 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.
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 infection with a second virus could 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. There is also evidence that smoking increases the fibrosis (scarring) rate.
During pregnancy and breastfeeding:
If a woman who is pregnant has risk factors for hepatitis C, she should be tested for antibodies against HCV. About 4% infants born to HCV infected women become infected. There is no treatment that can prevent this from happening. There is a high chance of the baby ridding the HCV in the first 12 months.
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.
HCV antibodies from the mother may persist in infants until 15 months of age. If an early diagnosis is desired, testing for 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 should avoid breastfeeding if her nipples are cracked and bleeding.
Prevention:
The following guidelines will prevent infection with the hepatitis C virus, which is spread by blood:
.Avoid sharing drug needles or any other drug paraphernalia including works for injection or bills or straws
.Avoid unsanitary tattoo methods
.Avoid unsanitary body piercing methods
.Avoid unsanitary acupuncture
.Avoid needlestick injury
.Avoid sharing personal items such as toothbrushes, razors, and nail clippers.
.Use latex condoms correctly and every time you have sex if not in a long-term monogamous relationship.
Proponents of harm reduction believe that strategies such as the provision of new needles and syringes, and education about safer drug injection procedures, greatly decreases the risk of hepatitis C spreading between injecting drug users.
No vaccine protects against contracting hepatitis C, or helps to treat it. Vaccines are under development and some have shown encouraging results.
Pollution increases risk of liver disease:
Environmental pollution is likely to increase the risk of liver disease among the adult population, something which was unknown earlier, says a new study.
This work builds upon the groups' previous research demonstrating liver disease in highly-exposed chemical workers.
'Our study found that greater than one in three US adults had liver disease, even after excluding those with traditional risk factors such as alcoholism and viral hepatitis,' said Matthew Cave, a professor at the University of Louisville (UL).
'Our study shows that some of these cases may be attributable to environmental pollution, even after adjusting for obesity, which is another major risk factor for liver disease,' he said.
Using the 2003-2004 National Health and Nutrition Examination Survey (NHANES), UL researchers examined chronic low-level exposure to 111 common pollutants including lead, mercury and pesticides and their association with otherwise unexplained liver disease in adults.
The specific pollutants included were detectable in 60 percent or more of the 4,500 study subjects, said a UL release.
Cave will present these data in Chicago at the Digestive Disease Week 2009 (DDW), the largest international gathering of physicians and researchers in gastroenterology, hepatology, endoscopy and gastrointestinal surgery.
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