HEPATITIS-B (Part-I)

Hepatitis B (HBV)

  What is Hepatitis B

The term 'hepatitis' simply means localized reaction that produces redness, warmth, swelling, and pain as a result of infection, irritation, or injury of the liver. Inflammation can be external or internal of the liver. Hepatitis may be caused by a virus. Two more type of virus causes Hepatitis-A and Hepatitis-C .

 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.

·         Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic disease.

·         The virus is transmitted through contact with the blood or other body fluids of an infected person - not through casual contact.

·         It is world wide syndrome ,2 billion people worldwide have been infected with the virus and about 350 million live with chronic infection. Censes shows that  about 600 000 persons die each year due to the acute or chronic consequences of hepatitis B.

·         About 25% of adults who become chronically infected during childhood later die from liver cancer or cirrhosis (scarring of the liver) caused by the chronic infection.

·         The hepatitis B virus is 50 to 100 times more infectious than HIV.

·         Hepatitis B virus is an important occupational hazard for health workers.

·         Hepatitis B is preventable with a safe and effective vaccine.

Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus. It causes  major global health problem and the most serious type of viral hepatitis. It can cause chronic liver disease and puts people at high risk of death from cirrhosis of the liver and liver cancer.

A vaccine against hepatitis B has been available since 1982. Hepatitis B vaccine is 95% effective in preventing HBV infection and its chronic consequences, and is the first vaccine against a major human cancer.

 

Symptoms

Hepatitis B virus can cause an acute illness with symptoms that last several weeks, including yellowing of the skin and eyes (jaundice), dark urine, extreme fatigue, nausea, vomiting and abdominal pain.

People can take several months to a year to recover from the symptoms. HBV can also cause a chronic liver infection that can later develop into cirrhosis of the liver or liver cancer.

What are the symptoms of acute hepatitis B?

Acute hepatitis B is the period of illness that occurs during the first one to four months after acquiring the virus. Only 30% to 50% of adults develop significant symptoms during acute infection. Early symptoms may be non-specific, including fever. a flu-like illness, and joint pains. Symptoms of acute hepatitis may include:

·         Fatigue,

·         Loss of appetite,

·         Nausea

·         Jaundice (yellowing of the skin and eyes), and

·         pain in the upper right abdomen (due to the inflamed liver).

Rarely, acute hepatitis damages the liver so badly it can no longer function. This life-threatening condition is called "fulminant hepatitis." Patients with fulminant hepatitis are at risk of developing bleeding problems and coma resulting from the failure of the liver. Patients with fulminant hepatitis should be evaluated for liver transplantation. Small studies suggest that the drug lamivudine (Epivir), may be of limited assistance in these cases (see below).

What determines the outcome of acute hepatitis B?

The body's immune response is the major determinant of the outcome in acute hepatitis B. Individuals who develop a strong immune response to the infection are more likely to clear the virus and recover. However, these patients also are more likely to develop more severe liver injury and symptoms due to the strong immune response that is trying to eliminate the virus. On the other hand, a weaker immune response results in less liver injury and fewer symptoms but a higher risk of developing chronic hepatitis B. People who recover and eliminate the virus will develop life-long immunity, that is, protection from subsequent infection from hepatitis B.

Most infants and children who acquire acute hepatitis B viral infection have no symptoms. In these individuals, the immune system fails to mount a vigorous response to the virus. Consequently, the risk of an infected infant developing chronic hepatitis B is greater than 95%. In contrast, only 5% of adults who have acute hepatitis B develop chronic hepatitis B.

What are the symptoms of chronic hepatitis B?

The liver is a vital organ that has many functions. These include a role in the immune system, production of clotting factors, producing bile for digestion, and breaking down toxic substances, etc. Patients with chronic hepatitis B develop symptoms in proportion to the degree of abnormalities in these functions. The signs and symptoms of chronic hepatitis B vary widely depending on the severity of the liver damage. They range from few and relatively mild signs and symptoms to signs and symptoms of severe liver disease such as cirrhosis or liver failure.

Most individuals with chronic hepatitis B remain symptom free for many years or decades. During this time, the patient's blood tests usually are normal or only mildly abnormal. Some patients may deteriorate and develop inflammation or symptoms, putting them at risk for developing cirrhosis.

Cirrhosis of the liver due to hepatitis B

Inflammation from chronic hepatitis B can progress to cirrosis (severe scarring) of the liver. Significant amounts of scarring and cirrhosis lead to liver dysfunction.

Symptoms may include:

·         Weakness,

·         fatigue,

·         loss of appetite,

·         weight loss

·         breast enlargement in men,

·         a rash on the palms,

·         difficulty with blood clotting, and

·         spider-like blood vessels on the skin.

Decreased absorption of vitamins A and D can cause impaired vision at night and thinning of bones (osteoporosis). Patients with liver cirrhosis also are at risk of infections because the liver plays an important role in the immune system.

Advanced cirrhosis of the liver due to hepatitis B

In patients with advanced cirrhosis, the liver begins to fail. This is life-threatening condition.

Several complications occur in advanced cirrhosis:

·        Confusion and even coma (encephalopathy) results from the inability of the liver to detoxify certain toxic substances.

·         Increased pressure in the blood vessels of the liver (portal hypertension) causes fluid to build up in the abdominal cavity (ascitis) and may result in engorged veins in the swallowing tube (esophageal varices) that tear easily and may cause massive bleeding.

·         Portal hypertension can also cause kidney falure or an enlargement spleen resulting in a decrease of blood cells and the development of anemia, increased risk of infection and bleeding.

·         In advanced cirrhosis, liver failure also results in decreased production of clotting factors. This causes abnormalities in blood clotting and sometimes spontaneous bleeding.

·         Patients with advanced cirrhosis often develop jaundice because the damaged liver is unable to eliminate a yellow compound, called bilirubin.

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 (in apparent infection through close interpersonal contact with infected household contacts)

·         unsafe injections practices

·         blood transfusions

·         sexual contact

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.

 

What is the scope of the problem?

Hepatitis B is an infection of the liver caused by the hepatitis B virus (HBV).As per report of Centers for Disease Control (CDC), approximately 46,000 new cases of hepatitis B occurred in the United States in 2011.

When a person first gets hepatitis B, they are said to have an 'acute' infection. Most people are able to eliminate the virus and are cured of the infection. Some are not able to clear the virus and have 'chronic' infection with hepatitis B that is usually life-long (see below).

What kind of a virus is hepatitis B?

The hepatitis B virus is a DNA (Deoxyribonucleic acid) virus, its means that it 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.

How does hepatitis B virus cause liver injury?

The hepatitis B virus reproduces in liver cells, but the virus itself is not the direct cause of damage to the liver. Rather, the presence of the virus triggers an immune response immune response from the body as the body tries to eliminate the virus and recover from the infection. This immune response causes inflammation and may seriously injure liver calls. Therefore, there is a balance between the protective and destructive effects of the immune response to the hepatitis B virus.

 

What is new in the treatment of hepatitis B virus?

The new development of  nucleoside/nucleotide analogues, they are help in treatment of  hepatitis B. Scientists also are working on treatment guidelines and the use of multi-drug therapy. Vaccination remains the key to preventing hepatitis B and holds the most promise for reducing disease burden.

How Hepatitis B virus transmitted?

Hepatitis B is spread mainly by exposure to infected blood or body secretions. In infected individuals, the virus can be found in the blood,semen,vaginal dischrge, breast milk, and saliva. Hepatitis B is not spread through food, water, or by casual contact.

Sexual contact is the most common means of transmission, followed by using contaminated needles for injecting illicit drugs, tattooing, body piercing, or acupuncture. Additionally, hepatitis B can be transmitted through sharing toothbrushes and razors contaminated with infected fluids or blood.

Hepatitis B also may be spread from infected mothers to their babies at birth (so-called 'vertical' transmission). This is the most prevalent means of transmission in regions of the world where hepatitis B rates are high. The rate of transmission of hepatitis B from mother to newborn is very high, and almost all infected infants will develop chronic hepatitis B. Fortunately,transmission can be significantly reduced through immunoprophylaxis.

Hepatitis B can be transmitted through transfused blood products, donated livers and other organs. However, blood and organ donors are routinely screened for hepatitis which typically prevents this type of transmission.