Hepatitis B in the context of "Viral hepatitis"

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.

Hepatitis B virus (HBV) is a partially double-stranded DNA virus, a species of the genus Orthohepadnavirus and a member of the Hepadnaviridae family of viruses. This virus causes the disease hepatitis B.

Hepatitis D is a type of viral hepatitis caused by the hepatitis delta virus (HDV). HDV is one of five known hepatitis viruses: A, B, C, D, and E. HDV is considered to be a satellite (a type of subviral agent) because it can propagate only in the presence of the hepatitis B virus (HBV). Transmission of HDV can occur either via simultaneous infection with HBV (coinfection) or superimposed on chronic hepatitis B or hepatitis B carrier state (superinfection).

HDV infecting a person with chronic hepatitis B (superinfection) is considered the most serious type of viral hepatitis due to its severity of complications. These complications include a greater likelihood of experiencing liver failure in acute infections and a rapid progression to liver cirrhosis, with an increased risk of developing liver cancer in chronic infections. In combination with hepatitis B virus, hepatitis D has the highest fatality rate of all the hepatitis infections, at 20%. A recent estimate from 2020 suggests that currently 48 million people are infected with this virus.

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.

Neonatal infections are infections of the neonate (newborn) acquired during prenatal development or within the first four weeks of life. Neonatal infections may be contracted by mother to child transmission, in the birth canal during childbirth, or after birth. Neonatal infections may present soon after delivery, or take several weeks to show symptoms. Some neonatal infections such as HIV, hepatitis B, and malaria do not become apparent until much later. Signs and symptoms of infection may include respiratory distress, temperature instability, irritability, poor feeding, failure to thrive, persistent crying and skin rashes.

Risk factors include previous maternal infection, preterm delivery (< 37 weeks gestation) and premature rupture of membranes (breakage of the amniotic sac) which substantially increases the risk of neonatal sepsis by allowing passage for bacteria to enter the womb prior to the birth of the infant. Preterm or low birth weight neonates are more vulnerable to neonatal infection. While preterm neonates are at a particularly high risk, all neonates can develop infection. Maternal screening for intrapartum infections reduce the risk of neonatal infection. Pregnant women may receive intrapartum antibiotic prophylaxis for prevention of neonatal infection.

Hepatitis B vaccine is a vaccine that prevents hepatitis B. The first dose is recommended within 24 hours of birth with either two or three more doses given after that. This includes those with poor immune function such as from HIV/AIDS and those born premature. It is also recommended that health-care workers be vaccinated. In healthy people, routine immunization results in more than 95% of people being protected.

Blood testing to verify that the vaccine has worked is recommended in those at high risk. Additional doses may be needed in people with poor immune function but are not necessary for most people. In those who have been exposed to the hepatitis B virus but not immunized, hepatitis B immune globulin should be given in addition to the vaccine. The vaccine is given by injection into a muscle.

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.

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide.

HCC most commonly occurs in those with chronic liver disease especially those with cirrhosis or fibrosis, which occur in the setting of chronic liver injury and inflammation. HCC is rare in those without chronic liver disease. Chronic liver diseases which greatly increase the risk of HCC include hepatitis infection such as (hepatitis B, C or D), non-alcoholic steatohepatitis (NASH), alcoholic liver disease, or exposure to toxins such as aflatoxin, or pyrrolizidine alkaloids. Certain diseases, such as hemochromatosis and alpha 1-antitrypsin deficiency, markedly increase the risk of developing HCC. The five-year survival in those with HCC is 18%.