Heptodes B?

Question

HEPOTODES B DISEASE

Answer 1

Hepatitis B is a disease of the liver caused by the Hepatitis B virus (HBV), a member of the Hepadnavirus family[1] and one of several unrelated viral species which cause viral hepatitis. It was originally known as "serum hepatitis" and has caused current epidemics in parts of Asia and Africa[2]. Hepatitis B is recognized as endemic in China and various other parts of Asia[3]. The proportion of the world's population currently infected with the virus is 3 to 6% but up to a third have been exposed. Symptoms of the acute illness caused by the virus include liver inflammation, vomiting, jaundice, and rarely, death. Chronic hepatitis B may cause liver cirrhosis which may then lead to liver cancer. Worldwide, the hepatitis B virus is the most important cause of cancer in humans after tobacco smoke.

Structure
Virions consist of an outer lipid envelope and an icosahedral nucleocapsid core, the latter being composed of both protein and DNA. The outer envelope contains embedded proteins which are involved in viral binding of, and release into, susceptible cells. Virion shape is generally spherical but pleomorphic forms exist, including filamentous forms, and spherical bodies lacking a core. The diameter ranges from 40 - 48 nm.

The DNA genome is not segmented and partially double-stranded, containing a long and short segment which overlap approximately 240 nucleotides to form a closed circle. The longer strand is 3020-3320 nucleotides long, and the shorter is 1700-2800 nucleotides long[4].


Replication
Hepatitis B is one of a few known non-retroviral viruses which employ reverse transcription as a part of its replication process. Other, unrelated, viruses which use reverse transcription include HIV, the virus which causes AIDS. Hepatitis B's genome is DNA, and reverse transcription is one of the later steps in making new viral particles, whereas HIV has an RNA genome and reverse transcription is one of the first steps in replication.

Upon entry into a host cell, the virus's double-stranded DNA genome is relocated to the cell's nucleus where viral mRNAs are transcribed. Three transcripts encoding the envelope proteins are made, along with a poorly understood transcript encoding the X protein, whose function is still under debate[1]. A fourth pre-genomic RNA is transcribed, which is exported to the cytosol and translates the viral polymerase and core proteins. Polymerase and pre-genomic RNA are encapsidated in the assembling core particles, where reverse transcription of the pre-genomic RNA to genomic DNA occurs by the polymerase protein. The mature core particle then exits the cell via normal secretory pathways, acquiring an envelope along the way.

Transmission
Hepatitis B is largely transmitted through exposure to bodily fluids containing the virus. This includes unprotected sexual contact, blood transfusions, re-use of contaminated needles and syringes, vertical transmission from mother to child during childbirth, and so on. The primary method of transmission depends on the prevalence of the disease in a given area. In low prevalence areas, such as the continental United States, IV drug abuse and unprotected sex are the primary methods. In moderate prevalence areas, the disease is predominantly spread among children. In high prevalence areas, such as South East Asia, vertical transmission is most common. Without intervention, a mother who is positive for the hepatitis B surface antigen confers a 20% risk of passing the infection to her offspring at the time of birth. This risk is as high as 90% if the mother is also positive for the hepatitis B e antigen.

Roughly 16-40% of unimmunized sexual partners of individuals with hepatitis B will be infected through sexual contact. The risk of transmission is closely related to the rate of viral replication in the infected individual at the time of exposure.

Immunopathogenesis
During HBV infection the host immune response is responsible for both hepatocellular damage and viral clearance. While the innate immune response does not play a significant role in these processes, the adaptive immune response, particularly virus-specific cytotoxic T lymphocytes (CTLs), contributes to nearly all of the liver injury associated with HBV infection. By killing infected cells and by producing antiviral cytokines capable of purging HBV from viable hepatocytes, CTLs also eliminate the virus[5]. Although liver damage is initiated and mediated by the CTLs, antigen-nonspecific inflammatory cells can worsen CTL-induced immunopathology and platelets may facilitate the accumulation of CTLs into the liver[6].

Symptoms and complications
Hepatitis B virus infection may either be acute (self-limited) or chronic (long-standing). Persons with self-limited infection clear the infection spontaneously within weeks to months.

The greater a person's age at the time of infection, the greater the chance their body will clear the infection. More than 95% of people who become infected as adults or older children will stage a full recovery and develop protective immunity to the virus. However, only 5% of new-borns that acquire the infection from their mother at birth will clear the infection. Of those infected between the age of one to six, 70% will clear the infection. When the infection is not cleared, one becomes a chronic carrier of the virus.

Acute infection with hepatitis B virus is associated with acute viral hepatitis - an illness that begins with general ill-health, loss of appetite, nausea, vomiting, bodyaches, mild fever, dark urine, and then progresses to development of jaundice. It has also been noted that itchy skin all over the body, has been an indication as a possible symptom of all hepatitis virus types. The illness lasts for a few weeks and then gradually improves in most of the affected people. A few patients may have more severe liver disease (fulminant hepatic failure), and may die as a result of it. The infection may also be entirely asymptomatic and may go unrecognized.

Chronic infection with hepatitis B virus may be either asymptomatic or may be associated with a chronic inflammation of the liver (chronic hepatitis), leading to cirrhosis over a period of several years. This type of infection dramatically increases the incidence of liver cancer.

Hepatitis D infection requires a concomitant infection with hepatitis B. Co-infection with hepatitis D increases the risk of liver cirrhosis and subsequently, liver cancer.

Polyarteritis nodosa is more common in people with hepatitis B infection.

Diagnosis
The original 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 with this virus; 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. 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 serologic evidence of disease.

Shortly after the appearance of the HBsAg, another antigen named as the hepatitis B e antigen (HBeAg) will appear.[2] Traditionally, the presence of HBeAg in a host's serum is associated with much higher rates of viral replication; however, some variants of the hepatitis B virus do not produce the 'e' antigen at all, 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 afterward. This conversion is usually associated with a dramatic decline in viral replication. If the host is able to clear the infection, eventually the HBsAg will become undetectable and will be followed by antibodies to the hepatitis B surface antigen (anti-HBs).[1] A person negative for HBsAg but positive for anti-HBs has either cleared an infection or has been vaccinated previously. A number of persons who are positive for HBsAg may have very little viral multiplication, and hence may be at little risk of long-term complications or of transmitting infection to others.

More recently, PCR tests have been developed to detect and measure the amount of viral nucleic acid in clinical specimens. These tests are useful to assess a person's infection status and to monitor treatment.

Treatment
There are currently several treatments for chronic hepatitis B that can increase a person's chance of clearing the infection. Treatments are available in the form of antivirals such as lamivudine and adefovir and immune system modulators such as interferon alpha. There are several other antivirals under investigation. Roughly, all of the currently available treatments, when used alone, are about equally efficacious. However, some individuals are much more likely to respond than others. It does not appear that combination therapy offers any advantages[7]. In general, each works by reducing the viral load by several orders of magnitude thus helping a body's immune system clear the infection. Treatment strategies should be individualized by a doctor and patient. Considerations include the risks associated with each treatment, a person's likelihood of clearing the virus with treatment, a person's risk for developing complications of persistent infection, and development of viral resistance with some of the treatments.

On March 29, 2005, the US Food and Drug Administration (FDA) approved Entecavir for the treatment of hepatitis B.

On February 25, 2005, the EU Commission approved PEGASYS for the treatment of hepatitis B making it the first pegylated interferon to be approved for hepatitis B.

Chronic carriers should be strongly encouraged to avoid consuming alcohol as it increases their risk for cirrhosis and hepatocellular carcinoma (liver cancer).

Infants born to mothers known to carry hepatitis B can be treated with antibodies to the hepatitis B virus (hepatitis B immune globulin or HBIg). When given with the vaccine within twelve hours of birth, the risk of acquiring hepatitis B is reduced 95%. This treatment also allows a mother to safely breastfeed her child.

An individual exposed to the virus who has never been vaccinated may be treated with HBIg immediately following the exposure. For instance, a health care worker accidentally stuck by a needle used in a hepatitis B carrier would qualify. Treatment must be soon after exposure, however.

Prevention
Several vaccines have been developed for the prevention of hepatitis B virus infection. These rely on the use of one of the viral proteins (hepatitis B surface antigen or HBsAg). The vaccine was originally prepared from plasma obtained from patients who had long-standing hepatitis B virus infection. However, currently, these are more often made using recombinant technology, though plasma-derived vaccines continue to be used; the two types of vaccines are equally effective and safe.

Many countries now routinely vaccinate infants against hepatitis B. In many areas, vaccination against hepatitis B is also required for all health-care workers. Some college campus housing units now require proof of vaccination as a prerequisite. Booster doses are not needed for low-risk general population. Some recommend such doses every five to ten years for health-care workers, though the evidence supporting such doses is quite limited.

The vaccine is highly effective. In endemic countries with high rates of hepatitis B infection, vaccination of newborns has not only reduced the risk of infection, but has also led to marked reduction in liver cancer. This was reported in Taiwan where a nationwide hepatitis B vaccination program was implemented in 1984 was associated with a decline in the incidence of childhood hepatocellular carcinoma.[8] In that sense, this vaccine can be thought of as an anti-cancer vaccine.

Patients with HIV appear to have inferior antibody responses to hepatitis B vaccination.[9]

Answer 2

It is Hepatitis B Disease.
Look it up at.
www.medscape.com
or
www.webmd.com

Answer 3

Do you mean hepatitis B?

Answer 4

Hepatitis B

Hepatitis B is one of the major diseases of mankind and is a serious global public health problem. It is preventable with safe and effective vaccines that have been available since 1982. Of the 2 billion people who have been infected with the hepatitis B virus (HBV), more than 350 million have chronic (lifelong) infections. These chronically infected persons are at high risk of death from cirrhosis of the liver and liver cancer, diseases that kill about one million persons each year. Although the vaccine will not cure chronic hepatitis, it is 95% effective in preventing chronic infections from developing, and is the first vaccine against a major human cancer. In 1991, the World Health Organization (WHO) called for all children to receive the hepatitis B vaccine, and 116 countries have added this vaccine to their routine immunization programmes. However, the children in the poorest countries, who need the vaccine the most, have not been receiving it because their governments cannot afford it. Fortunately, hepatitis B vaccine will soon be available in these countries with the assistance of the Global Alliance for Vaccines and Immunization (GAVI) and the Global Fund for Children's Vaccines.

What is hepatitis?

Hepatitis means inflammation of the liver, and the most common cause is infection with one of 5 viruses, called hepatitis A,B,C,D, and E. All of these viruses can cause an acute disease with symptoms lasting several weeks including yellowing of the skin and eyes (jaundice); dark urine; extreme fatigue; nausea; vomiting and abdominal pain. It can take several months to a year to feel fit again. Hepatitis B virus can cause chronic infection in which the patient never gets rid of the virus and many years later develops cirrhosis of the liver or liver cancer. HBV is the most serious type of viral hepatitis and the only type causing chronic hepatitis for which a vaccine is available.

Who gets hepatitis B?

In much of the developing world, (sub-Saharan Africa, most of Asia, and the Pacific), most people become infected with HBV during childhood, and 8% to 10% of people in the general population become chronically infected. In these regions liver cancer caused by HBV figures among the first three causes death by cancer in men.

High rates of chronic HBV infection are also found in the Amazon and the southern parts of Eastern and Central Europe. In the Middle East and Indian sub-continent, about 5% are chronically infected. Infection is less common in Western Europe and North America, where less than 1% are chronically infected.

Young children who become infected with HBV are the most likely to develop chronic infection. About 90% of infants infected during the first year of life and 30% to 50% of children infected between 1 to 4 years of age develop chronic infection. The risk of death from HBV-related liver cancer or cirrhosis is approximately 25% for persons who become chronically infected during childhood.

How do people get infected ?

Hepatitis B virus is transmitted by contact with blood or body fluids of an infected person in the same way as human immunodeficiency virus (HIV), the virus that causes AIDS. However, HBV is 50 to 100 times more infectious than HIV.

The main ways of getting infected with HBV are:

* Perinatal (from mother to baby at the birth)
* Child-to-child transmission
* Unsafe injections and transfusions
* Sexual contact

Worldwide, most infections occur from infected mother to child, from child to child contact in household settings, and from reuse of unsterilized needles and syringes. In many developing countries, almost all children become infected with the virus.

In many industrialized countries (e.g. Western Europe and North America), the pattern of transmission is different. In these countries, mother-to-infant and child-to-child transmission accounted for up to one third of chronic infections before childhood hepatitis B vaccination programmes were implemented. However, the majority of infections in these countries are acquired during young adulthood by sexual activity, and injecting drug use. In addition, hepatitis B virus is the major infectious occupational hazard of health workers, and most health care workers have received hepatitis B vaccine.

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

Can chronic hepatitis B and liver cancer be treated?

Liver cancer is almost always fatal, and usually develops between 35 and 65 years of age, when people are maximally productive and with family responsibilities. The loss of a mother or a father in a developing country can devastate the entire family. In developing countries, most people with liver cancer die within months of diagnosis. In industrialized countries, surgery and chemotherapy can prolong life up to a few years. Chronic hepatitis B in some patients is treated with drugs called interferon or lamivudine, which can help some patients. However, interferon or lamivudine therapy costs thousands of dollars and will never be available to most patients in developing countries. Patients with cirrhosis are sometimes given liver transplants, with varying success. It is preferable to prevent this disease with vaccine than to try and cure it.

How safe and effective is the vaccine?

Hepatitis B vaccine has an outstanding record of safety and effectiveness. Since 1982, over one billion doses of hepatitis B vaccine have been used worldwide. The vaccine is given as a series of three intramuscular doses. Studies have shown that the vaccine is 95% effective in preventing children and adults from developing chronic infection if they have not yet been infected. In many countries where 8% to 15% of children used to become chronically infected with HBV, the rate of chronic infection has been reduced to less than 1% in immunized groups of children.

How is WHO trying to control hepatitis B?

Since 1991, WHO has called for all countries to add hepatitis B vaccine into their national immunization programmes. As of March 2000, 116 countries had included hepatitis B vaccine in their national programmes including most countries in Eastern and South- East Asia, the Pacific Islands, Australia, North and South America, Western Europe and the Middle East. However, many low income countries in sub-Saharan Africa, the Indian subcontinent and in the Newly Independent States do not use the vaccine. The price of the hepatitis B vaccine has been one of the main obstacles to its introduction in many of these countries.

The Global Alliance for Vaccines and Immunization (GAVI) was created in 1999. It is a unique coalition of public and private institutions where WHO has taken a leading role. The main mission of GAVI is to vaccinate as many children as possible against vaccine-preventable diseases. GAVI has introduced a new approach to international health funding: the Global Fund for Children's vaccines (GFCV). This fund will help 74 low-income countries to reinforce their national vaccine programmes and introduce hepatitis B, yellow fever and haemophilus influenzae type b(Hib) vaccines into their national immunization programmes.