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Information About Hepatitis B

What is hepatitis?

The term ‘hepatitis’ simply means inflammation of the liver. Hepatitis may be caused by a virus or a toxin such as alcohol. Other viruses that can cause injury to liver cells include the hepatitis A and hepatitis C viruses. These viruses are not related to each other or to hepatitis B virus and differ in their structure, the ways they are spread among individuals, the severity of symptoms they can cause, the way they are treated, and the outcome of the infection.

What kind of a virus is hepatitis B?

The hepatitis B virus is a DNA virus, meaning that its genetic material is made up of deoxyribonucleic acids. It belongs to a family of viruses known as Hepadnaviridae. The virus is primarily found in the liver but is also present in the blood and certain body fluids.

Hepatitis B virus consists of a core particle (central portion) and a surrounding envelope (outer coat). The core is made up of DNA and the core antigen (HBcAg). The envelope contains the surface antigen (HBsAg). These antigens are present in the blood and are markers that are used in the diagnosis and evaluation of patients with suspected viral hepatitis.

Causes, incidence, and risk factors:

Hepatitis B infection can be spread through having contact with the blood, semen, vaginal fluids, and other body fluids of someone who already has a hepatitis B infection.

Infection can be spread through:

•       Blood transfusions (not common in the United States)
•       Direct contact with blood in health care settings
•       Sexual contact with an infected person
•       Tattoo or acupuncture with unclean needles or instruments
•       Shared needles during drug use
•       Shared personal items (such as toothbrushes, razors, and nail clippers) with an infected person

The hepatitis B virus can be passed to an infant during childbirth if the mother is infected.

Risk factors for hepatitis B infection include:

•       Being born, or having parents who were born in regions with high infection rates (including Asia, Africa, and the Caribbean)
•       Being infected with HIV
•       Being on hemodialysis
•       Having multiple sex partners
•       Men having sex with men

Most of the damage from the hepatitis B virus occurs because of the way the body responds to the infection. When the body’s immune system detects the infection, it sends out special cells to fight it off. However, these disease-fighting cells can lead to liver inflammation.

Hepatitis B:

Hepatitis B is an infectious inflammatory illness of the liver caused by the hepatitis B virus (HBV) that affects hominoidea, including humans. Originally known as “serum hepatitis”,the disease has caused epidemics in parts of Asia and Africa, and it is endemic in China.About a third of the world population has been infected at one point in their lives,including 350 million who are chronic carriers.

The virus is transmitted by exposure to infectious blood or body fluids such as semen and vaginal fluids, while viral DNA has been detected in the saliva, tears, and urine of chronic carriers. Perinatal infection is a major route of infection in endemic (mainly developing) countries.Other risk factors for developing HBV infection include working in a healthcare setting, transfusions, and dialysis, acupuncture, tattooing, extended overseas travel and residence in an institution. However, Hepatitis B viruses cannot be spread by holding hands, sharing eating utensils or drinking glasses, kissing, hugging, coughing, sneezing, or breastfeeding.

The acute illness causes liver inflammation, vomiting, jaundice, and (rarely) death. Chronic hepatitis B may eventually cause cirrhosis and liver cancer—a disease with poor response to all but a few current therapies. The infection is preventable by vaccination.

Hepatitis B virus is an hepadnavirus—hepa from hepatotropic (attracted to the liver) and dna because it is a DNA virus and it has a circular genome of partially double-stranded DNA. The viruses replicate through an RNA intermediate form by reverse transcription, which practice relates them to retroviruses.Although replication takes place in the liver, the virus spreads to the blood where viral proteins and antibodies against them are found in infected people.

Transmission:

Hepatitis B virus is transmitted between people by contact with the blood or other body fluids (i.e. semen and vaginal fluid) of an infected person. Modes of transmission are the same for the human immunodeficiency virus (HIV), but HBV is 50 to 100 times more infectious Unlike HIV, HBV can survive outside the body for at least 7 days. During that time, the virus can still cause infection if it enters the body of a person who is not infected.

Common modes of transmission in developing countries are:

•     perinatal (from mother to baby at birth)
•     early childhood infections (inapparent infection through close interpersonal contact with infected household contacts)
•     unsafe injections practices
•     blood transfusions
•     sexual contact

In many developed countries (e.g. those in western Europe and North America), patterns of transmission are different than those mentioned above. Today, the majority of infections in these countries are transmitted during young adulthood by sexual activity and injecting drug use. HBV is a major infectious occupational hazard of health workers.

HBV is not spread by contaminated food or water, and cannot be spread casually in the workplace.

The virus incubation period is 90 days on average, but can vary from about 30 to 180 days. HBV may be detected 30 to 60 days after infection and persist for widely variable periods of time.

Hepatitis B Overview:

Hepatitis B is an infectious hepatitis caused by the hepatitis B virus (HBV). This infection has two possible phases; 1) acute and 2) chronic.

•     Acute hepatitis B refers to newly acquired infections. Affected individuals notice symptoms approximately 1 to 4 months after exposure to the virus. In most people with acute hepatitis, symptoms resolve over weeks to months and they are cured of the infection. However, a small number of people develop a very severe, life-threatening form of acute hepatitis called fulminant hepatitis.
•     Chronic hepatitis B is an infection with HBV that lasts longer than 6 months. Once the infection becomes chronic, it may never go away completely.

Approximately 90% to 95% of infected adults are able to fight off the virus so their infection is cured. Only about 5% to 10% of adults infected with HBV go on to develop chronic infection. Children are at much higher risk for chronic infection. Up to 90% of infected young children will fail to clear the virus from their bodies and go on to develop chronic infection.

About two-thirds of people with chronic HBV infection are chronic carriers. These people do not develop symptoms, even though they harbor the virus and can transmit it to other people. The remaining one third develop “active” hepatitis, a disease of the liver that can be very serious.

•     The liver is an important organ that filters toxins out of the blood, stores energy for later use, helps with digestion, and makes substances that fight infections and control bleeding.
•     The liver has an incredible ability to heal itself, but long-term inflammation caused by HBV can result in permanent damage.
•     Scarring of the liver is called cirrhosis, a condition traditionally associated with alcoholism but one that is also caused by chronic active hepatitis B infection. When this occurs, the liver can no longer carry out its normal functions and may fail completely. The only treatment for liver failure is liver transplant.

Complications:

There is a much higher rate of hepatocellular carcinoma in people who have chronic hepatitis B than in the general population.

Other complications may include:

•       Chronic persistent hepatitis
•       Cirrhosis
•       Fulminant hepatitis, which can lead to liver failure and possibly death

Diagnosis:

The tests, called assays, for detection of hepatitis B virus infection involve serum or blood tests that detect either viral antigens (proteins produced by the virus) or antibodies produced by the host. Interpretation of these assays is complex.

The hepatitis B surface antigen (HBsAg) is most frequently used to screen for the presence of this infection. It is the first detectable viral antigen to appear during infection. However, early in an infection, this antigen may not be present and it may be undetectable later in the infection as it is being cleared by the host. The infectious virion contains an inner “core particle” enclosing viral genome. The icosahedral core particle is made of 180 or 240 copies of core protein, alternatively known as hepatitis B core antigen, or HBcAg. During this ‘window’ in which the host remains infected but is successfully clearing the virus, IgM antibodies to the hepatitis B core antigen (anti-HBc IgM) may be the only serological evidence of disease.

Shortly after the appearance of the HBsAg, another antigen called hepatitis B e antigen (HBeAg) will appear. Traditionally, the presence of HBeAg in a host’s serum is associated with much higher rates of viral replication and enhanced infectivity; however, variants of the hepatitis B virus do not produce the ‘e’ antigen, so this rule does not always hold true. During the natural course of an infection, the HBeAg may be cleared, and antibodies to the ‘e’ antigen (anti-HBe) will arise immediately afterwards. This conversion is usually associated with a dramatic decline in viral replication.
Ground glass hepatocytes as seen in a chronic hepatitis B. Liverbiopsy. H&E stain.

If the host is able to clear the infection, eventually the HBsAg will become undetectable and will be followed by IgG antibodies to the hepatitis B surface antigen and core antigen, (anti-HBs and anti HBc IgG).The time between the removal of the HBsAg and the appearance of anti-HBs is called the window period. A person negative for HBsAg but positive for anti-HBs either has cleared an infection or has been vaccinated previously.

Individuals who remain HBsAg positive for at least six months are considered to be hepatitis B carriers.Carriers of the virus may have chronic hepatitis B, which would be reflected by elevated serum alanine aminotransferase (ALT) levels and inflammation of the liver, as revealed by biopsy. Carriers who have seroconverted to HBeAg negative status, in particular those who acquired the infection as adults, have very little viral multiplication and hence may be at little risk of long-term complications or of transmitting infection to others.

PCR tests have been developed to detect and measure the amount of HBV DNA, called the viral load, in clinical specimens. These tests are used to assess a person’s infection status and to monitor treatment.Individuals with high viral loads, characteristically have ground glass.

Treatment:

Acute hepatitis B infection does not usually require treatment because most adults clear the infection spontaneously.Early antiviral treatment may be required in fewer than 1% of people, whose infection takes a very aggressive course (fulminant hepatitis) or who are immunocompromised. On the other hand, treatment of chronic infection may be necessary to reduce the risk of cirrhosis and liver cancer. Chronically infected individuals with persistently elevated serum alanine aminotransferase, a marker of liver damage, and HBV DNA levels are candidates for therapy. Treatment lasts from six months to a year, depending on medication and genotype.

Although none of the available drugs can clear the infection, they can stop the virus from replicating, thus minimizing liver damage. Currently, there are seven medications licensed for treatment of hepatitis B infection in the United States. These include antiviral drugs lamivudine (Epivir), adefovir (Hepsera), tenofovir (Viread), telbivudine (Tyzeka) and entecavir (Baraclude), and the two immune system modulators interferon alpha-2a and PEGylated interferon alpha-2a (Pegasys). The use of interferon, which requires injections daily or thrice weekly, has been supplanted by long-acting PEGylated interferon, which is injected only once weekly.However, some individuals are much more likely to respond than others, and this might be because of the genotype of the infecting virus or the person’s heredity. The treatment reduces viral replication in the liver, thereby reducing the viral load (the amount of virus particles as measured in the blood).Response to treatment differs between the genotypes. Interferon treatment may produce an e antigen seroconversion rate of 37% in genotype A but only a 6% seroconversion in type D. Genotype B has similar seroconversion rates to type A while type C seroconverts only in 15% of cases. Sustained e antigen loss after treatment is ~45% in types A and B but only 25–30% in types C and D.

Acute hepatitis needs no treatment other than careful monitoring of liver and other body functions with blood tests. You should get plenty of bed rest, drink plenty of fluids, and eat healthy foods.

In the rare case that you develop liver failure, you may need a liver transplant. A liver transplant is the only cure in some cases of liver failure.

Some patients with chronic hepatitis may be treated with antiviral medications or a medication called peginterferon. These medications can decrease or remove hepatitis B from the blood and reduce the risk of cirrhosis and liver cancer.

Liver transplantation is used to treat severe, chronic hepatitis B liver disease.

Patients with chronic hepatitis should avoid alcohol and should always check with their doctor or nurse before taking any over-the-counter medications or herbal supplements. This even includes medications such as acetaminophen, aspirin, or ibuprofen.