Hepatitis B

Hepatitis B is a infectious disease of the liver caused by the hepatitis B virus (HBV) a member of the hepadnavirus viral family. The disease can either have an acute self-limiting course like hepatitis A, or it can have a chronic presentation. The clinical manifestations of HBV infection range in severity from no symptoms to fulminant hepatitis. Hepatitis B is is found all over the world and an estimated 620,000 persons worldwide die from HBV-related liver disease each year.



Other Names

 * Type B hepatitis
 * Serum hepatitis
 * Homologous serum jaundice
 * Australia antigen hepatitis
 * HB

Types
Hepatitis B infection can result in either acute illness or chronic disease.


 * Acute hepatitis B is the illness seen soon after infection. Most people with acute hepatitis B clear the virus from their bodies within weeks to months.
 * Chronic hepatitis B can develop in people who have had the acute infection and represents persistence of the hepatitis B virus in the liver, usually for at least 20 weeks since the initial infection.
 * Chronic asymptomatic carrier is someone who carries the hepatitis B virus in the liver but has no symptoms.
 * Chronic persistent hepatitis B is seen in people who carry the virus and who have evidence of ongoing mild liver impairment. Most have no symptoms, do not have jaundice, and most will recover without sequelae.
 * Chronic active hepatitis B represents ongoing liver damage in people who are infected with hepatitis B virus. The outcome may be cirrhosis or liver cancer.

Acute hepatitis B
Many hepatitis B virus infections are asymptomatic and may not be clinically recognizable. Less than 10% of children, few newly infected immunosuppressed patients, and between 30%-50% of adults infected with HBV show icteric disease (i.e., jaundice or a yellow discoloration of the skin, whites of the eyes, and the mucous membranes). When present, sign and symptoms will begin an average of 90 days (range: 60-150 days) after exposure to HBV and can include:


 * Jaundice
 * Fever
 * Fatigue
 * Loss of appetite
 * Nausea
 * Vomiting
 * Abdominal pain
 * Dark urine
 * Clay-colored bowel movements
 * Joint pain

Symptoms typically last for several weeks but can persist for up to 6 months, and they are more severe among adults over 60 years of age.

Chronic hepatitis B
The risk for chronic infection varies according to the age at infection and is greatest among young children. In some studies, approximately 90% of infants and 30% of children aged less than 5 years have remained chronically infected with Hepatitis B virus (HBV). Other studies have found a lower incidence of chronic infection in children. By contrast, approximately 95% of adults recover completely from HBV infection and do not become chronically infected. Approximately 25% of those who become chronically infected during childhood and 15% of those who become chronically infected after childhood die prematurely from cirrhosis or liver cancer, and the majority remain asymptomatic until onset of cirrhosis or end-stage liver disease.

Persons with chronic HBV infection might be asymptomatic, have no evidence of liver disease, or have a spectrum of disease ranging from chronic hepatitis to cirrhosis or hepatocellular carcinoma (a type of liver cancer).

Diagnosis
There are several blood test that can detect the hepatitis B virus in the blood (antigen tests) or that can detect antibodies to the virus that have been produced by the body. These tests can be used to determine the clinical stage of infection. The tests include the following:
 * Hepatitis B surface antigen (HBsAg): Is a protein on the surface of HBV; it can be detected in high levels in serum during acute or chronic HBV infection. The presence of HBsAg indicates that the person is infectious (can transmit the virus to other people). The body normally produces antibodies to HBsAg as part of the normal immune response to infection. HBsAg will be detected in an infected person's blood an average of 4 weeks (range: 1 - 9 weeks) after exposure to the virus. HBsAg is the antigen used to make hepatitis B vaccine.


 * Hepatitis B surface antibody (anti-HBs): The presence of anti-HBs is generally interpreted as indicating recovery and immunity from HBV infection. Anti-HBs also develops in a person who has been successfully vaccinated against hepatitis B.


 * Total hepatitis B core antibody (anti-HBc): Appears at the onset of symptoms in acute hepatitis B and persists for life. The presence of anti-HBc indicates previous or ongoing infection with HBV in an undefined time frame.


 * IgM antibody to hepatitis B core antigen (IgM anti-HBc): Positivity indicates recent infection with HBV (less than 6 months), its presence indicates acute infection.


 * Hepatitis B e antigen (HBeAg): A secreted product of the gene of HBV that is found in serum during acute and chronic hepatitis B. Its presence indicates that the virus is replicating and the infected person has high levels of HBV.

The following table provides interpretations for hepatitis B serologic markers.
 * Hepatitis B e antibody (HBeAb or anti-HBe): Produced by the immune system temporarily during acute HBV infection, or consistently during or after a burst in viral replication. Spontaneous conversion from e antigen to e antibody (a change known as seroconversion) is a predictor of long-term clearance of HBV in patients undergoing antiviral therapy and indicates lower levels of HBV.

Treatment
For acute infection, no medication is available; treatment is supportive.

For chronic disease treatment will depend on evidence of viral activity, HBeAg status, HIV and HCV comorbidity, histologic (view of cells under a microscope) evidence of liver injury, and elevated liver function tests. For chronic infection, several antiviral drugs (adefovir dipivoxil, interferon alfa-2b, pegylated interferon alfa-2a, lamivudine, entecavir, and telbivudine) are available, and other new therapies are being studied. Persons with chronic HBV infection require medical evaluation and regular monitoring to determine whether the disease is progressing and to identify liver damage or hepatocellular carcinoma.

Prevention
Prevention is the most important aspect of stopping the spread of hepatitis B.

General Measures
Any blood spills, including dried blood, which can still be infectious, should be cleaned using 1:10 dilution of one part household bleach to 10 parts of water for disinfecting the area (after it is diluted, bleach loses its effectiveness in a short period of time). Gloves should be used when cleaning up any blood spills.

Vaccination
Effective hepatitis B vaccines have been available since the early 1980s and should be used whenever possible unless contraindicated (should not be used because of serious allergic reaction to a prior dose of hepatitis B vaccine, to a component of the hepatitis B vaccine, or baking yeast).

See Hepatitis B Vaccination for more information.

Living with
There are some steps a person who is a carrier of HBV can take to help prevent the spread of this disease.


 * Washing hands with soap after touching blood or body fluids. Throwing contaminated personal items such as tissues, menstrual pads, tampons, or bandages away in a plastic bag.


 * All cuts and open sores should be covered with a bandage.


 * Wiping up blood spills, then, re-cleaning the area with a solution of one part household bleach to ten parts water.


 * Telling sexual partners of hepatitis B status. Partners should be tested for HBV, and if not immune to the virus, they should receive the vaccination series of three shots. Condoms should be used to help prevent the spread of HBV and other sexually transmitted illnesses.


 * Review of all medications with physician; even some over-the-counter and alternative medicines can harm the liver.


 * Periodic ultrasound and alpha-fetoprotein blood tests for liver cancer.

Things NOT to do:


 * Avoid drinking alcohol; the liver may be further damaged by alcohol. If alcohol is consumed, do not take acetaminophen (found in Tylenol or other cold and headache remedies) at the same time.
 * Do not share toothbrushes, razors, needles, syringes, nail files, clippers, scissors, or any object that may come into contact with blood or body fluids.
 * Do not share food that has been in the mouth and do not pre-chew food for babies.
 * Do not donate blood, plasma, body organs, tissues, or sperm.

Chances of Developing
The following populations are at increased risk of becoming infected with HBV:


 * Infants born to infected mothers.
 * Sex partners of infected persons.
 * Sexually active persons who are not in a long-term, mutually monogamous relationship (e.g., more than 1 sex partner during the previous 6 months).
 * Men who have sex with men.
 * Injection drug users.
 * Household contacts of persons with chronic HBV infection.
 * Healthcare and public safety workers at risk for occupational exposure to blood or blood-contaminated body fluids.
 * Residents and staff of facilities for developmentally disabled persons.
 * Travelers to countries with intermediate or high prevalence of HBV infection.

How is Spread
HBV is transmitted through activities that involve percutaneous (i.e., puncture through the skin) or mucosal contact with infectious blood or body fluids (e.g., semen, saliva). Such activities include the following:


 * Sex with an infected partner.
 * Injection drug use that involves sharing needles, syringes, or drug-preparation equipment.
 * An infected mother giving birth.
 * Contact with blood or open sores of an infected person.
 * Needle sticks or sharp instrument exposures.
 * Sharing items such as razors or toothbrushes with an infected person.

HBV is not spread through food or water, by sharing eating utensils, breast feeding, hugging, kissing, hand holding, coughing, or sneezing.

HBV can survive outside the body at least 7 days and still be capable of causing infection.

Clinical Trials
Hepatitis B open clinical trials can be found at ClinicalTrials.gov

Expected Outcome
Most people who develop acute hepatitis B disease will have resolution of the infection and will have life-long immunity to reinfection with the hepatitis B virus.

Rarely, a small number of people may develop a fulminant form of acute hepatitis B that can lead to liver failure and death.

Three to five percent of people with acute disease can have relapses or prolonged acute symptoms persisting beyond three to four months. If relapses of acute symptoms does occur, illness tends to be milder.

A serum sickness-like syndrome (rash, fever, joint pains or frank arthritis) has been seen in up to 10% of people who are incubating hepatitis B (clinical hepatitis B has not yet developed).

People who have cirrhosis (scarring of the liver) due to chronic hepatitis B infection are at increased risk for developing hepatocellular carcinoma (liver cancer).

Epidemiology
Worldwide infection with HBV is endemic with little seasonal variation. WHO (World Health Organization) estimates approximately 2 billion persons have been infected with HBV, including 350 million chronically infected. In 2006, 4,758 cases of acute hepatitis B were reported to the CDC; the overall incidence of reported acute hepatitis B was 1.6 per 100,000 population, the lowest ever recorded. Because many HBV infections are either asymptomatic or never reported, however, the actual number of new infections is estimated to be approximately tenfold higher. In 2006, an estimated 46,000 persons were newly infected with HBV. Rates are highest among adults, particularly males aged 25-44 years.

The rate of new HBV infections has declined by approximately 80% since 1991, when a national strategy to eliminate HBV infection was implemented in the United States. The decline has been greatest among children born since 1991, when routine vaccination of children was first recommended.

An interesting fact is that premenopausal women have a decreased risk of progression to chronic hepatitis B compared to men and postmenopausal women. This is thought to be due to a protective role of estrogen.

Public Health
Most countries and states will have their own mechanisms of prevention and control of hepatitis B and communicable diseases. When two or more cases occur in association with some common exposure it is recommended to search for additional cases. If a blood derivative like antihemophilic factor, fibrinogen, pooled plasma or thrombin is implicated, the source should be withdrawn from use and all recipients should be contacted and tested.