هپاتیت سی (به انگلیسی: Hepatitis C) یک بیماری عفونی-ویروسی است که توسط ویروس هپاتیت سی موسوم به HCV ایجاد میشود و یک ویروس دارای پوشش با RNA مثبت است و جزو فلاوی ویروس طبقه بندی می شود. آلودگی به این ویروس باعث التهاب در پارانشیم کبد میگردد. در بیشتر موارد٬ آغاز این بیماری بدون نشانه(سمپتوم) است اما در مراحل پیشرفته بهگونه سیروز کبدی* و در موارد کمتر سرطان کبد بروز میکند. واگیری بیماری از راه خون آلوده انجام میگیرد، و در بیمارانی که پیشینه بکارگیری مواد مخدر تزریقی، انتقال خون آلوده، یا خالکوبی با سوزن آلوده را دارند بیشتر دیده میشود. از دیگر راههای انتقال ارتباط جنسی است که درصد کمتری را به خود اختصاص میدهد. اغلب کارسینوم در یاختههای کبدی پیآمد این هپاتیت است. درمان اصلی آن با کمک انواع اینترفرون بویژه آلفا و نیز داروی ریباویرین است. دچارشدن به این بیماری از بیشترین زمینهسازهای پیوند کبد در جهان به شمار میرود.
نشانه و علائم [ویرایش]
راههاي انتقال [ویرایش]
تشخیص اولیه هپاتیت سی به ندرت در طی مرحلهٔ حاد این بیماری انجام شده، چراکه بیشتر افراد آلوده هیچ نشانهای را در طول این مرحله تجربه نمیکنند. کسانی هم که اندک علائمی در مرحله حاد بیماری دارند٬ بهاندازه کافی به دنبال مراقبتهای پزشکی نیستند تا به پزشک مراجعه کنند. تشخیص در فاز مزمن هپاتیت سی نیز چالش برانگیز است چراکه به دلیل عدم وجود علائم ویژه و تا زمان پیشرفت کامل بیماری و تخریب کبد، که تا سالها ممکن است ادامه داشتهباشد٬ معمولاً پنهان میماند. در بیشتر مواقع٬ تشخیص یک هپاتیت مزمن کهنه٬ توسط پزشک یا پرستار و بهصورت اتفاقی صورت میگیرد٬ جاییکه در تاریخچه پزشکی بیمار و یا بر بدن بیمار آثار تزریق مواد و یا خالکوبی(تتو) دیده میشود و بهدنبال آن آزمایشهای خونی ویژه درخواست میگردد.
بههرحال ویژگی غالب بالینی در تشخیص هپاتیت مزمن٬ هیپرترانسآمینازی یا بالا بودن ترانسآمیناز است و برای ارزیابی شدت آسیب بافت، با استفاده از شاخص فعالیت بافتی* نکروز در پریپورتال٬ آسیب پارانشیم٬ التهاب پورتال و در نهایت فیبروز مدنظر قرار میگیرند. در ۷۰٪ تا ۹۰٪ پروندهها(بسته به مدتزمان ابتلا به ویروس) میتوان با آزمایشهای سرولوژی میزان پادتن ویروس (HCV antibody) را اندازهگیری و پی به وجود ویروس(و نه عفونت هپاتیتی) در بدن برد و این بدان معناست که صرف وجود پادتن(آنتیبادی) در بدن برای تشخیص عفونت کافی نبوده و نیاز به آزمایشهای تکمیلی در جهت تأیید عفونت هپاتیت در بافت کبد میباشد. در هرصورت انجام آزمایشهای روتین روشی معمول است و بهعنوان راههای شناخت زودهنگام وجود بیماری در بدن نیز کاربرد دارد.
پیشگیری و درمان [ویرایش]
 هپاتیت سی بهندرت بهبودی کامل به همراه دارد و استراحت٬ رژیم غذایی و غیره در درمان بیفایده است. بهترین روش پیشگیری از ابتلا بوده و رعایت بهداشت وایمنی بین پرسنل بیمارستانی و استفاده از تجهیزاتی همچون دستکش٬ دوری و اجتناب از روشهای ناهنجار و پرخطر اجتماعی همچون اعتیاد تزریقی و ارتباط جنسی نامطمئن٬ پذیرش و احترام به حقوق بیمار در کلینیک پزشکی و دندانپزشکی و ارائهٔ خدمات با استاندارد بهداشتی٬ آموزش و تشویق خانوادهها برای انجام آزمایشهای سالیانه معمولی(چکآپ) و خدمات پیشگیرانهٔ مرتبط با سلامت و بهداشت از اصلیترین روشهای آن است.
در میانهٔ سال ۲۰۱۱ اداره مواد غذائی و داروئی ایالات متحده آمریکا مجوز دو داروی جدید بوسپرویر*(با نام تجاری ویکترلیس) و تلاپرویر*(با نام تجاری اینسیوک) را برای درمان(کنترل) هپاتیت سی٬ صادر نمودهاست. هرچند هنوز در بیماران مبتلا به ویروس اچسیوی درمانهای روتین استفاده از انواع اینترفرون بویژه اینترفرون آلفا و آنتیویرال(داروهای ضدویروس) مانند ریباویرین است.
همهگیر شناسی [ویرایش]
از دید اپیدمیولوژی حدود ۳ درصد از مردم جهان(بین ۱۳۰ تا ۱۷۰ میلیون نفر) به هپاتیت سی مبتلا هستند و تندی انتشار آن چیزی نزدیک به ۳ میلیون نفر در سال است. بیش از ۱۰ درصد این مبتلایان به سوی سیروز و سرطان رفته و هرساله نزدیکبه ۳۵۰هزار قربانی مرگ بهدنبال دارد.
کشورهای دارای میزان ابتلای بالا به هپاتیت سی بهترتیب مصر با ۲۲٪ ٬ پاکستان ۴/۸٪ و چین با ۳/۲٪ در فهرست سازمان بهداشت جهانی قرار داشته و بزرگترین راه پخش ویروس در هر سه کشور٬ آلودگی از راه تزریق و خون اعلام شدهاست.
در ایران پژوهشهای رسمی بر روی جمعیت عمومی کشور ۱/۰ درصد جمعیت کشور را آلوده به هپاتیت سی تخمین زده ولی طبق آمار غیر رسمی٬ بین ۲۰۰ تا ۳۰۰ هزار نفر مبتلا به هپاتیت سی یعنی ۱/۳ درصد جمعیت کشور به ویروس هپاتیت سی آلوده هستند. . آنچه که هپاتیت سی را دلیل نگرانی قرار میدهد وجود آمار ۶۰ تا ۸۰ درصدی افراد آلوده به هپایتت سی است که به سمت مزمن شدن بیماری میروند و هرچند شیوع آن نسبت به هپاتیت بی کمتر است اما مشکل و پیآمدهای مربوط به هپاتیت سی به دلیل میل به مزمن شدن٬ بیشتراست. عامل دیگر همسایگی ایران با کشورهای دارای شیوع بالای هپاتیت همچون پاکستان است. در سال ۱۳۷۹ در زندانهای ایران اپیدمی هپاتیت سی نزدیکبه ۲۰ درصد بوده که با دراختیار گذاشتن سرنگ یک بار مصرف در بین زندانیان و همچنین کمک به تغییر اعتیاد آنها از تزریقی به خوراکی، این بیماری کاهش یافت و در سال ۸۴ آمار مربوط به معتادان تزریقی مبتلا به هپاتیت سی به حدود ۵ درصد کاهش نشان دادهاست.
Hepatitis C is an infectious disease affecting primarily the liver, caused by the hepatitis C virus (HCV). The infection is often asymptomatic, but chronic infection can lead to scarring of the liver and ultimately to cirrhosis, which is generally apparent after many years. In some cases, those with cirrhosis will go on to develop liver failure, liver cancer or life-threatening esophageal and gastric varices.
HCV is spread primarily by blood-to-blood contact associated with intravenous drug use, poorly sterilized medical equipment and transfusions. An estimated 130–200 million people worldwide are infected with hepatitis C. The existence of hepatitis C (originally "non-A non-B hepatitis") was postulated in the 1970s and proven in 1989. Hepatitis C only infects humans and chimpanzees.
The virus persists in the liver in about 85% of those infected. This persistent infection can be treated with medication: the standard therapy is a combination of peginterferon and ribavirin, with either boceprevir or telaprevir added in some cases. Overall, 50–80% of people treated are cured. Those who develop cirrhosis or liver cancer may require a liver transplant. Hepatitis C is the leading cause of liver transplantation, though the virus usually recurs after transplantation. No vaccine against hepatitis C is available.
Signs and symptoms
Hepatitis C infection causes acute symptoms in 15% of cases. Symptoms are generally mild and vague, including a decreased appetite, fatigue, nausea, muscle or joint pains, and weight loss and rarely does acute liver failure result. Most cases of acute infection are not associated with jaundice. The infection resolves spontaneously in 10-50% of cases, which occurs more frequently in individuals who are young and female.
About 80% of those exposed to the virus develop a chronic infection. Most experience minimal or no symptoms during the initial few decades of the infection, although chronic hepatitis C can be associated with fatigue. Hepatitis C after many years becomes the primary cause of cirrhosis and liver cancer. About 10–30% of people develop cirrhosis over 30 years. Cirrhosis is more common in those co-infected with hepatitis B or HIV, alcoholics, and those of male gender. Those who develop cirrhosis have a 20-fold greater risk of hepatocellular carcinoma, a rate of 1–3% per year, and if this is complicated by excess alcohol the risk becomes 100 fold greater. Hepatitis C is the cause of 27% of cirrhosis cases and 25% of hepatocellular carcinoma worldwide.
Liver cirrhosis may lead to portal hypertension, ascites (accumulation of fluid in the abdomen), easy bruising or bleeding, varices (enlarged veins, especially in the stomach and esophagus), jaundice, and a syndrome of cognitive impairment known as hepatic encephalopathy. It is a common cause for requiring a liver transplant.
Hepatitis C is also rarely associated with Sjögren's syndrome (an autoimmune disorder), thrombocytopenia, lichen planus, diabetes mellitus, and B-cell lymphoproliferative disorders. Thrombocytopenia is estimated to occur in 0.16% to 45.4% of people with chronic hepatitis C. Putative associations with Hyde's prurigo nodularis  and membranoproliferative glomerulonephritis have been reported. Hepatitis C infection is also associated with a condition called mixed cryoglobulinemia, which is inflammation of small and medium sized blood vessels (or vasculitis) caused by deposition of immune complexes involving cryoglobulins.
The hepatitis C virus (HCV) is a small, enveloped, single-stranded, positive-sense RNA virus. It is a member of the hepacivirus genus in the family Flaviviridae. There are seven major genotypes of HCV, which are indicated numerically from one to seven. In the United States, about 70% of cases are caused by genotype 1, 20% by genotype 2, and about 1% by each of the other genotypes. Genotype 1 is also the most common in South America and Europe.
The primary route of transmission in the developed world is intravenous drug use (IDU), while in the developing world the main methods are blood transfusions and unsafe medical procedures. The cause of transmission remains unknown in 20% of cases; however, many of these are believed to be accounted for by IDU.
Intravenous drug use
IDU is a major risk factor for hepatitis C in many parts of the world. Of 77 countries reviewed 25 (including the United States) were found to have prevalences of hepatitis C in the intravenous drug user population of between 60% and 80%. Twelve countries had rates greater than 80%. It is believed that ten million intravenous drug users are infected with hepatitis C; China (1.6 million), the United States (1.5 million), and Russia (1.3 million) have the highest absolute totals. Occurrence of hepatitis C among prison inmates in the United States is 10 to 20 times that of the occurrence observed in the general population; this has been attributed to high-risk behavior in prisons such as IDU and tattooing with nonsterile equipment.
Blood transfusion, transfusion of blood products, or organ transplantation without HCV screening carry significant risks of infection. The United States instituted universal screening in 1992 and Canada instituted universal screening in 1990. This decreased the risk from one in 200 units to between one in 10,000 to one in 10,000,000 per unit of blood. This low risk remains as there is a period of about 11–70 days between the potential blood donor acquiring hepatitis C and their blood testing positive depending on the method. Some countries do not screen for hepatitis C due to the cost.
Those who have experienced a needle stick injury from someone who was HCV positive have about a 1.8% chance of subsequently contracting the disease themselves. The risk is greater if the needle in question is hollow and the puncture wound is deep. There is a risk from mucosal exposures to blood; but this risk is low, and there is no risk if blood exposure occurs on intact skin.
Hospital equipment has also been documented as a method of transmission of hepatitis C including: reuse of needles and syringes, multiple-use medication vials, infusion bags, and improperly sterilized surgical equipment, among others. Limitations in the implementation and enforcement of stringent standard precautions in public and private medical and dental facilities are known to be the primary cause of the spread of HCV in Egypt, the country with highest rate of infection in the world.
Whether hepatitis C can be transmitted through sexual activity is controversial. While there is an association between high-risk sexual activity and hepatitis C, it is not known whether transmission of the disease is due to drug use that has not been admitted to or sex as a risk factor. The majority of evidence supports there being no risk for monogamous heterosexual couples. Sexual practices that involve higher levels of trauma to the anogenital mucosa, such as anal penetrative sex, or that occur when there is a concurrent sexually transmitted infection, including HIV or genital ulceration, do present a risk. The United States government only recommends condom use to prevent hepatitis C transmission in those with multiple partners.
Tattooing is associated with two to threefold increased risk of hepatitis C. This can be due to either improperly sterilized equipment or contamination of the dyes being used. Tattoos or piercings performed either before the mid-1980s, "underground," or nonprofessionally are of particular concern, since sterile techniques in such settings may be lacking. The risk also appears to be greater for larger tattoos. It is estimated that nearly half of prison inmates share unsterilized tattooing equipment. It is rare for tattoos in a licensed facility to be directly associated with HCV infection.
Personal-care items such as razors, toothbrushes, and manicuring or pedicuring equipment can be contaminated with blood. Sharing such items can potentially lead to exposure to HCV. Appropriate caution should be taken regarding any medical condition that results in bleeding, such as cuts and sores. HCV is not spread through casual contact, such as hugging, kissing, or sharing eating or cooking utensils. Neither is it transmitted through food or water.
Vertical transmission of hepatitis C from an infected mother to her child occurs in less than 10% of pregnancies. There are no measures that alter this risk. It is not clear when during pregnancy transmission occurs, but it may occur both during gestation and at delivery. A long labor is associated with a greater risk of transmission. There is no evidence that breast-feeding spreads HCV; however, to be cautious, an infected mother is advised to avoid breastfeeding if her nipples are cracked and bleeding, or her viral loads are high.
There are a number of diagnostic tests for hepatitis C including: HCV antibody enzyme immunoassay or ELISA, recombinant immunoblot assay, and quantitative HCV RNA polymerase chain reaction (PCR). HCV RNA can be detected by PCR typically one to two weeks after infection, while antibodies can take substantially longer to form and thus be detected.
Chronic hepatitis C is defined as infection with the hepatitis C virus persisting for more than six months based on the presence of its RNA. Chronic infections are typically asymptomatic during the first few decades, and thus are most commonly discovered following the investigation of elevated liver enzyme levels or during a routine screening of high risk individuals. Testing is not able to distinguish between acute and chronic infections.
Hepatitis C testing typically begins with blood testing to detect the presence of antibodies to the HCV using an enzyme immunoassay. If this test is positive, a confirmatory test is then performed to verify the immunoassay and to determine the viral load. A recombinant immunoblot assay is used to verify the immunoassay and the viral load is determined by a HCV RNA polymerase chain reaction. If there are no RNA and the immunoblot is positive it means that the person had a previous infection but cleared it either with treatment or spontaneously; if the immunoblot is negative, it means that the immunoassay was wrong. It takes about 6–8 weeks following infection before the immunoassay will test positive. A number of tests are available as point of care testing which means that results are available within 30 minutes.
Liver biopsies are used to determine the degree of liver damage present; however, there are risks from the procedure. The typical changes seen are lymphocytes within the parenchyma, lymphoid follicles in portal triad, and changes to the bile ducts. There are a number of blood tests available that try to determine the degree of hepatic fibrosis and alleviate the need for biopsy.
It is believed only 5–50% of those infected in the United States and Canada become aware of their status. Testing is recommended in those at high risk, which includes those with tattoos. Screening is also recommended in those with elevated liver enzymes as this is frequently the only sign of chronic hepatitis. Routine screening is not currently recommended in the United States. However, in 2012, the U.S. Centers for Disease Control and Prevention (CDC) recommended a single screening test for those born between 1945 and 1965.
As of 2011[update], no vaccine protects against contracting hepatitis C. However, a number are under development and some have shown encouraging results. A combination of harm reduction strategies, such as the provision of new needles and syringes and treatment of substance use, decrease the risk of hepatitis C in intravenous drug users by about 75%. The screening of blood donors is important at a national level, as is adhering to universal precautions within healthcare facilities. In countries where there is an insufficient supply of sterile syringes, medications should be given orally rather than via injection (when possible).
HCV induces chronic infection in 50–80% of infected persons. Approximately 40-80% of these clear with treatment. In rare cases, infection can clear without treatment. Those with chronic hepatitis C are advised to avoid alcohol and medications toxic to the liver, and to be vaccinated for hepatitis A and hepatitis B. Ultrasound surveillance for hepatocellular carcinoma is recommended in those with accompanying cirrhosis.
In general, treatment is recommended in those with proven HCV infection liver abnormalities. As of 2010[update], treatments consists of a combination of pegylated interferon alpha and the antiviral drug ribavirin for a period of 24 or 48 weeks, depending on HCV genotype. When combined with ribavirin, pegylated interferon-alpha-2a may be superior to pegylated interferon-alpha-2b, though the evidence is not strong. Improved outcomes are seen in 50–60% of people. Combining either boceprevir or telaprevir with ribavirin and peginterferon alfa improves antiviral response for hepatitis C genotype 1. Adverse effects with treatment are common, with half of people getting flu like symptoms and a third experiencing emotional problems. Treatment during the first six months is more effective than once hepatitis C has become chronic. If someone develops a new infection and it has not cleared after eight to twelve weeks, 24 weeks of pegylated interferon is recommended. In people with thalassemia, ribavirin appears to be useful but increases the need for transfusions.
Several alternative therapies are claimed by their proponents to be helpful for hepatitis C including milk thistle, ginseng, and colloidal silver. However, no alternative therapy has been shown to improve outcomes in hepatitis C, and no evidence exists that alternative therapies have any effect on the virus at all.
Responses to treatment vary by HCV C genotype, and is measured by sustained viral response. Sustained response is about 40-50% in people with HCV genotype 1 given 48 weeks of treatment. Sustained response is seen in 70-80% of people with HCV genotypes 2 and 3 with 24 weeks of treatment. Sustained response is about 65% in those with genotype 4 given 48 weeks of treatment. The evidence for treatment in genotype 6 disease is sparse, and the evidence that exists is for 48 weeks of treatment at the same doses as are used for genotype 1 disease. Successful treatment decreases the future risk of hepatocellular carcinoma by three quarters.
It is estimated that 130–200 million people, or ~3% of the world's population, are living with chronic hepatitis C. About 3–4 million people are infected per year, and more than 350,000 people die yearly from hepatitis C-related diseases. Rates have increased substantially in the 20th century due to a combination of IDU and intravenous medication or poorly sterilized medical equipment.
Among those chronically infected, the risk of cirrhosis after 20 years varies between studies but has been estimated at ~10%-15% for men and ~1-5% for women. The reason for this difference is not known. Once cirrhosis is established, the rate of developing hepatocellular carcinoma is ~1%-4% per year.
In the United States, about 2% of people have hepatitis C, with about 35,000 to 185,000 new cases a year. Rates have decreased in the Western world since the 1990s due to improved screening of blood before transfusion. Annual deaths from HCV in the United States range from 8,000 to 10,000; expectations are that this mortality rate will increase, as those infected by transfusion before HCV testing become apparent.
Prevalence is higher in some countries in Africa and Asia. Countries with particularly high rates of infection include Egypt (22%), Pakistan (4.8%) and China (3.2%). It is believed that the high prevalence in Egypt is linked to a now-discontinued mass-treatment campaign for schistosomiasis, using improperly sterilized glass syringes.
In the mid-1970s, Harvey J. Alter, Chief of the Infectious Disease Section in the Department of Transfusion Medicine at the National Institutes of Health, and his research team demonstrated how most post-transfusion hepatitis cases were not due to hepatitis A or B viruses. Despite this discovery, international research efforts 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, collaborating with Dr. D.W. Bradley at the Centers for Disease Control and Prevention, used a novel molecular cloning approach to identify the unknown organism and develop a diagnostic test. In 1988, the virus was confirmed by Alter by verifying its presence in a panel of NANBH specimens. In April 1989, the discovery of HCV was published in two articles in the journal Science. The discovery led to significant improvements in diagnosis and improved antiviral treatment. In 2000, Drs. Alter and Houghton were honored with the Lasker Award for Clinical Medical Research for "pioneering work leading to the discovery of the virus that causes hepatitis C and the development of screening methods that reduced the risk of blood transfusion-associated hepatitis in the U.S. from 30% in 1970 to virtually zero in 2000."
Chiron filed for several patents on the virus and its diagnosis. A competing patent application by the CDC was dropped in 1990 after Chiron paid $1.9 million to the CDC and $337,500 to Bradley. In 1994, Bradley sued Chiron, seeking to invalidate the patent, have himself included as a coinventor, and receive damages and royalty income. He dropped the suit in 1998 after losing before an appeals court.
Society and culture
World Hepatitis Day, held on July 28, is coordinated by the World Hepatitis Alliance. The economic costs of hepatitis C are significant both to the individual and to society. In the United States the average lifetime cost of the disease was estimated at 33,407 USD in 2003 with the cost of a liver transplant as of 2011[update] costing approximately 200,000 USD. In Canada the cost of a course of antiviral treatment is as high as 30,000 CAD in 2003, while the United States costs are between 9,200 and 17,600 in 1998 USD. In many areas of the world, people are unable to afford treatment with antivirals as they either lack insurance coverage or the insurance they have will not pay for antivirals.
As of 2011[update], there are about one hundred medications in development for hepatitis C. These include vaccines to treat hepatitis, immunomodulators, and cyclophilin inhibitors, among others. These potential new treatments have come about due to a better understanding of the hepatitis C virus.