Viral hepatitis in the context of "Hepatitis D virus"

Hepatitis is inflammation of the liver tissue. 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. Hepatitis is acute if it resolves within six months, and chronic if it lasts longer than six months. Acute hepatitis can resolve on its own, progress to chronic hepatitis, or (rarely) result in acute liver failure. Chronic hepatitis may progress to scarring of the liver (cirrhosis), liver failure, and liver cancer.

Hepatitis is most commonly caused by the virus hepatovirus A, B, C, D, and E. Other viruses can also cause liver inflammation, including cytomegalovirus, Epstein–Barr virus, and yellow fever virus. Other common causes of hepatitis include heavy alcohol use, certain medications, toxins, other infections, autoimmune diseases, and non-alcoholic steatohepatitis (NASH). Hepatitis A and E are mainly spread by contaminated food and water. Hepatitis B is mainly sexually transmitted, but may also be passed from mother to baby during pregnancy or childbirth and spread through infected blood. Hepatitis C is commonly spread through infected blood; for example, during needle sharing by intravenous drug users. Hepatitis D can only infect people already infected with hepatitis B.

Hepatitis A is an infectious liver disease caused by Hepatitis A virus (HAV); it is a type of viral hepatitis. Many cases have few or no symptoms, especially in the young. The time between exposure and symptoms, in those who develop them, is two to six weeks. When symptoms occur, they typically last eight weeks and may include nausea, vomiting, diarrhea, jaundice, fever, and abdominal pain. Around 10–15% of people experience a recurrence of symptoms during the six months after the initial infection. Acute liver failure may rarely occur, with this being more common in the elderly.

It is typically a foodborne illness, usually spread by eating food or drinking water contaminated with infected feces. Undercooked or raw shellfish are relatively common sources. It may also be spread through close contact with an infectious person. While children often do not have symptoms when infected, they are still able to infect others. After a single infection, a person is immune for the rest of their life. Diagnosis requires blood testing, as the symptoms are similar to those of a number of other diseases. It is one of five known hepatitis viruses: A, B, C, D, and E.

Hepatology is the branch of medicine that incorporates the study of liver, gallbladder, biliary tree, and pancreas as well as management of their disorders. Although traditionally considered a sub-specialty of gastroenterology, rapid expansion has led in some countries to doctors specializing solely on this area, who are called hepatologists.

Diseases and complications related to viral hepatitis and alcohol are the main reason for seeking specialist advice. More than two billion people have been infected with hepatitis B virus at some point in their life, and approximately 350 million have become persistent carriers. Up to 80% of liver cancers can be attributed to either hepatitis B or hepatitis C virus. In terms of mortality, the former is second only to smoking among known agents causing cancer. With more widespread implementation of vaccination and strict screening before blood transfusion, lower infection rates are expected in the future. In many countries, however, overall alcohol consumption is increasing, and consequently the number of people with cirrhosis and other related complications is commensurately increasing.

Hepatosplenomegaly (commonly abbreviated HSM) is the simultaneous enlargement of both the liver (hepatomegaly) and the spleen (splenomegaly). Hepatosplenomegaly can occur as the result of acute viral hepatitis, infectious mononucleosis, and histoplasmosis or it can be the sign of a serious and life-threatening lysosomal storage disease. Systemic venous hypertension can also increase the risk for developing hepatosplenomegaly, which may be seen in those patients with right-sided heart failure.

Hepatitis C is an infectious disease caused by the hepatitis C virus (HCV) that primarily affects the liver; it is a type of viral hepatitis. During the initial infection period, people often have mild or no symptoms. Early symptoms can include fever, dark urine, abdominal pain, and jaundice. The virus persists in the liver, becoming chronic, in about 70% of those initially infected. Early on, chronic infection typically has no symptoms. Over many years however, it often leads to liver disease and occasionally cirrhosis. In some cases, those with cirrhosis will develop serious complications such as liver failure, liver cancer, or dilated blood vessels in the esophagus and stomach.

HCV is spread primarily by blood-to-blood contact associated with injection drug use, poorly sterilized medical equipment, needlestick injuries in healthcare, and transfusions. In regions where blood screening has been implemented, the risk of contracting HCV from a transfusion has dropped substantially to less than one per two million. HCV may also be spread from an infected mother to her baby during birth. It is not spread through breast milk, food, water, or casual contact such as hugging, kissing, and sharing food or drinks with an infected person. It is one of five known hepatitis viruses: A, B, C, D, and E.Diagnosis is by blood testing to look for either antibodies to the virus or viral RNA. In the United States, screening for HCV infection is recommended in all adults age 18 to 79 years old.There is no vaccine against hepatitis C. Prevention includes harm reduction efforts among people who inject drugs, testing donated blood, and treatment of people with chronic infection. Chronic infection can be cured more than 95% of the time with antiviral medications such as sofosbuvir or simeprevir. Peginterferon and ribavirin were earlier generation treatments that proved successful in <50% of cases and caused greater side effects. While access to the newer treatments was expensive, by 2022 prices had dropped dramatically in many countries (primarily low-income and lower-middle-income countries) due to the introduction of generic versions of medicines. Those who develop cirrhosis or liver cancer may require a liver transplant. Hepatitis C is one of the leading reasons for liver transplantation. However, the virus usually recurs after transplantation.

Hepatitis B is an infectious disease caused by the hepatitis B virus (HBV) that affects the liver; it is a type of viral hepatitis. It can cause both acute and chronic infection.

Many people have no symptoms after exposure. For others, symptoms may appear 30 to 180 days after exposure and can include a rapid onset of sickness with nausea, vomiting, yellowish skin, fatigue, yellow urine, and abdominal pain. Symptoms during acute infection typically last for a few weeks, though some people may feel sick for up to six months. Deaths resulting from acute stage HBV infections are rare. An HBV infection lasting longer than six months is usually considered chronic. The likelihood of developing chronic hepatitis B is higher for those who are infected with HBV at a younger age. About 90% of those infected during or shortly after birth develop chronic hepatitis B, while less than 10% of those infected after the age of five develop chronic cases. Most of those with chronic disease have no symptoms; however, cirrhosis and liver cancer eventually develop in about 25% of those with chronic HBV.

Hepatitis E is inflammation of the liver caused by infection with the hepatitis E virus (HEV); it is a type of viral hepatitis. Hepatitis E has mainly a fecal-oral transmission route that is similar to hepatitis A, although the viruses are unrelated. HEV is a positive-sense, single-stranded, nonenveloped, RNA icosahedral virus and one of five known human hepatitis viruses: A, B, C, D, and E.

Like hepatitis A, hepatitis E usually follows an acute and self-limiting course of illness (the condition is temporary and the individual recovers) with low death rates in resource-rich areas; however, it can be more severe in pregnant women and people with a weakened immune system, with substantially higher death rates. In pregnant women, especially in the third trimester, the disease is more often severe and is associated with a clinical syndrome called fulminant liver failure, with death rates around 20%. Whereas pregnant women may have a rapid and severe course, organ transplant recipients who receive medications to weaken the immune system and prevent organ rejection can develop a slower and more persistent form called chronic hepatitis E, which is so diagnosed after 3 months of continuous viremia. HEV can be clustered genetically into 8 genotypes, and genotypes 3 and 4 tend to be the ones that cause chronic hepatitis in the immunosuppressed.