Hepatitis C

[Marketta Filipovich]

Hepatitisis an inflammation of the liver that is caused by avariety of infectious viruses and noninfectiousagents leading to a range of health problems, some of which can be fatal. Thereare five main strains of the hepatitis virus, referred to as types A, B, C, Dand E. While they all cause liver disease, they differ in important waysincluding modes of transmission, severity of the illness, geographicaldistribution and prevention methods. In particular, types B and C lead tochronic disease in hundreds of millions of people and together are the mostcommon cause of liver cirrhosis, liver cancer and viral hepatitis-relateddeaths. An estimated 354 million people worldwide live with hepatitis B or C,and for most, testing and treatment remain beyond reach.

Many people with hepatitis A, B, C, D or E exhibit only mild symptoms or no symptoms at all. Each form of the virus, however, can cause more severe symptoms. Symptoms of hepatitis A, B and C may include fever, malaise, loss of appetite, diarrhoea, nausea, abdominal discomfort, dark-coloured urine and jaundice (a yellowing of the skin and whites of the eyes). In some cases, the virus can also cause a chronic liver infection that can later develop into cirrhosis (a scarring of the liver) or liver cancer. These patients are at risk of death.

Hepatitis D (HDV) is only found in people already infected with hepatitis B (HBV); however, the dual infection of HBV and HDV can cause a more serious infection and poorer health outcomes, including accelerated progression to cirrhosis. Development of chronic hepatitis D is rare.

Hepatitis E (HEV) begins with mild fever, reduced appetite, nausea and vomiting lasting for a few days. Some persons may also have abdominal pain, itching (without skin lesions), skin rash or joint pain. They may also exhibit jaundice, with dark urine and pale stools, and a slightly enlarged, tender liver (hepatomegaly), or occasionally acute liver failure.

Safe and effective vaccines are available to prevent hepatitis B virus (HBV). This vaccine also prevents the development of hepatitis D virus (HDV) and given at birth strongly reduces transmission risk from mother to child. Chronic hepatitis B infection can be treated with antiviral agents. Treatment can slow the progression of cirrhosis, reduce incidence of liver cancer and improve long term survival. Only a proportion of people with chronic hepatitis B infection will require treatment. A vaccine also exists to prevent infections of hepatitis E (HEV), although it is not currently widely available. There are no specific treatments for HBV and HEV and hospitalization is not usually required. It is advised to avoid unnecessary medications due to the negative effect on liver function caused by these infections.

Hepatitis C (HCV) can cause both acute and chronic infection. Some people recover on their own, while others develop a life-threatening infection or further complications, including cirrhosis or cancer. There is no vaccine for hepatitis C. Antiviral medicines can cure more than 95% of persons with hepatitis C infection, thereby reducing the risk of death from cirrhosis and liver cancer, but access to diagnosis and treatment remains low.

Hepatitis A virus (HAV) is most common is low- and middle-income countries due to reduced access to clean and reliable water sources and the increased risk of contaminated food. A safe and effective vaccine is available to prevent hepatitis A. Most HAV infections are mild, with the majority of people recovering fully and developing immunity to further infection. However, these infections can also rarely be severe and life threatening due to the risk of liver failure.

Hepatitis is inflammation of the liver tissue.[3][5] Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes (jaundice), poor appetite, vomiting, tiredness, abdominal pain, and diarrhea.[1][2] Hepatitis is acute if it resolves within six months, and chronic if it lasts longer than six months.[1][6] Acute hepatitis can resolve on its own, progress to chronic hepatitis, or (rarely) result in acute liver failure.[7] Chronic hepatitis may progress to scarring of the liver (cirrhosis), liver failure, and liver cancer.[3][8]

Hepatitis A, B, and D are preventable with immunization.[2] Medications may be used to treat chronic viral hepatitis.[1] Antiviral medications are recommended in all with chronic hepatitis C, except those with conditions that limit their life expectancy.[10] There is no specific treatment for NASH; physical activity, a healthy diet, and weight loss are recommended.[9] Autoimmune hepatitis may be treated with medications to suppress the immune system.[11] A liver transplant may be an option in both acute and chronic liver failure.[4]

Hepatitis has a broad spectrum of presentations that range from a complete lack of symptoms to severe liver failure.[17][18][19] The acute form of hepatitis, generally caused by viral infection, is characterized by constitutional symptoms that are typically self-limiting.[17][18] Chronic hepatitis presents similarly, but can manifest signs and symptoms specific to liver dysfunction with long-standing inflammation and damage to the organ.[19][20]

Both drug-induced hepatitis and autoimmune hepatitis can present very similarly to acute viral hepatitis, with slight variations in symptoms depending on the cause.[21][22] Cases of drug-induced hepatitis can manifest with systemic signs of an allergic reaction including rash, fever, serositis (inflammation of membranes lining certain organs), elevated eosinophils (a type of white blood cell), and suppression of bone marrow activity.[21]

Acute cases of hepatitis are seen to be resolved well within a six-month period. When hepatitis is continued for more than six months it is termed chronic hepatitis.[23] Chronic hepatitis is often asymptomatic early in its course and is detected only by liver laboratory studies for screening purposes or to evaluate non-specific symptoms.[19][20] As the inflammation progresses, patients can develop constitutional symptoms similar to acute hepatitis, including fatigue, nausea, vomiting, poor appetite, and joint pain.[20] Jaundice can occur as well, but much later in the disease process and is typically a sign of advanced disease.[20] Chronic hepatitis interferes with hormonal functions of the liver which can result in acne, hirsutism (abnormal hair growth), and amenorrhea (lack of menstrual period) in women.[20] Extensive damage and scarring of the liver over time defines cirrhosis, a condition in which the liver's ability to function is permanently impeded.[19] This results in jaundice, weight loss, coagulopathy, ascites (abdominal fluid collection), and peripheral edema (leg swelling).[20] Cirrhosis can lead to other life-threatening complications such as hepatic encephalopathy, esophageal varices, hepatorenal syndrome, and liver cancer.[19]

Causes of hepatitis can be divided into the following major categories: infectious, metabolic, ischemic, autoimmune, genetic, and other. Infectious agents include viruses, bacteria, and parasites. Metabolic causes include prescription medications, toxins (most notably alcohol), and non-alcoholic fatty liver disease. Autoimmune and genetic causes of hepatitis involve genetic predispositions and tend to affect characteristic populations.[24]

Hepatitis B, hepatitis C, and hepatitis D are transmitted when blood or mucous membranes are exposed to infected blood and body fluids, such as semen and vaginal secretions.[17] Viral particles have also been found in saliva and breastmilk. Kissing, sharing utensils, and breastfeeding do not lead to transmission unless these fluids are introduced into open sores or cuts.[28] Many families who do not have safe drinking water or live in unhygienic homes have contracted hepatitis because saliva and blood droplets are often carried through the water and blood-borne illnesses spread quickly in unsanitary settings.[29]

Hepatitis B and C can present either acutely or chronically.[17] Hepatitis D is a defective virus that requires hepatitis B to replicate and is only found with hepatitis B co-infection.[17] In adults, hepatitis B infection is most commonly self-limiting, with less than 5% progressing to chronic state, and 20 to 30% of those chronically infected developing cirrhosis or liver cancer.[30] Infection in infants and children frequently leads to chronic infection.[30]

Unlike hepatitis B, most cases of hepatitis C lead to chronic infection.[31] Hepatitis C is the second most common cause of cirrhosis in the US (second to alcoholic hepatitis).[32] In the 1970s and 1980s, blood transfusions were a major factor in spreading hepatitis C virus.[31] Since widespread screening of blood products for hepatitis C began in 1992, the risk of acquiring hepatitis C from a blood transfusion has decreased from approximately 10% in the 1970s to 1 in 2 million currently.[17]

Parasites can also infect the liver and activate the immune response, resulting in symptoms of acute hepatitis with increased serum IgE (though chronic hepatitis is possible with chronic infections).[33] Of the protozoans, Trypanosoma cruzi, Leishmania species, and the malaria-causing Plasmodium species all can cause liver inflammation.[33] Another protozoan, Entamoeba histolytica, causes hepatitis with distinct liver abscesses.[33]

Of the worms, the cestode Echinococcus granulosus, also known as the dog tapeworm, infects the liver and forms characteristic hepatic hydatid cysts.[33] The liver flukes Fasciola hepatica and Clonorchis sinensis live in the bile ducts and cause progressive hepatitis and liver fibrosis.[33]

Bacterial infection of the liver commonly results in pyogenic liver abscesses, acute hepatitis, or granulomatous (or chronic) liver disease.[34] Pyogenic abscesses commonly involve enteric bacteria such as Escherichia coli and Klebsiella pneumoniae and are composed of multiple bacteria up to 50% of the time.[34] Acute hepatitis is caused by Neisseria meningitidis, Neisseria gonorrhoeae, Bartonella henselae, Borrelia burgdorferi, salmonella species, brucella species and campylobacter species.[34] Chronic or granulomatous hepatitis is seen with infection from mycobacteria species, Tropheryma whipplei, Treponema pallidum, Coxiella burnetii, and rickettsia species.[34]

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