Hepatitis B

Introduction

Hepatitis B is a potentially life-threatening disease caused by a virus that attacks the liver. The virus known as the hepatitis B virus (HBV) can cause life-long infection, and puts people at high risk of death from cirrhosis (scarring) of the liver, liver cancer and liver failure. It is a major global health problem and the most serious type of viral hepatitis. 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 Chronic hepatitis B also can lead to a type of liver cancer known as hepatocellular carcinoma. Any of these conditions can be fatal. About 15% to 25% percent of people with chronic hepatitis B die of liver disease.

MAGNITUDE OF THE DISEASE

Hepatitis B is the most common serious liver infection in the world. About 350 million people worldwide are chronic carriers of HBV, of whom, more than 620,000 die from liver-related disease each year. In the United States, Hepatitis B is largely a disease of young adults aged 20-50 years. About 800,000 to 1.4 million Americans are chronic Hepatitis B virus carriers, and the disease causes about 3, 000 deaths each year. Hepatitis B is also very common in Nigeria and affects at least 19 million or one in eight Nigerians.

TRANSMISSION

Hepatitis B virus is transmitted between people by direct blood-to-blood contact or semen and vaginal fluid of an infected person. Modes of transmission are the same as those for the human immunodeficiency virus (HIV), but the Hepatitis B virus is 50 to 100 times more infectious. Unlike HIV, the Hepatitis B virus can survive outside the body for at least seven days. During this time, the virus can still cause infection if it enters the body of a person who is not protected by the vaccine.

In our environment, common modes of transmission are:

•          prenatal (from mother to

•          baby at birth) early childhood infections (in apparent infection through close interpersonal contact with infected household contacts)

•          unsafe injection practices

•          unsafe blood transfusions

•          unprotected sexual contact.

In many developed countries (e.g. those in Western Europe and North America), patterns of transmission are different from those in

PHASES

This infection has two possible phases; 1) acute and 2) chronic.

1.        Acute hepatitis B refers to newly acquired infections. Affected individuals notice symptoms approximately 1- 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. It may never go away completely.

2.        Chronic hepatitis B is an infection with HBV that lasts longer than 6 months. Once the infection becomes chronic.

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.

SYMPTOMS

Most people infected with the Hepatitis B virus do not experience any symptoms during the acute infection phase. However, some people have acute illness with symptoms that develop within 30-180 days of exposure to the virus. The symptoms are often compared to flu. Most people think they have flu and never think about having HBV infection. The symptoms usually last several weeks and include:

•          Loss of appetite

•          Feeling tired (fatigue)

•          Nausea and vomiting

•          Itching all over the body

•          Pain over the liver (on the right side of the abdomen, under the lower rib cage)

•          Jaundice – A condition in which the skin and the whites of the eyes turn yellow in colour

•          Urine becomes dark in colour (like cola or tea).

•          Stools are pale in color (grayish or clay colored).

In some people, the Hepatitis B virus results in a chronic liver infection that can later develop into cirrhosis of the liver or liver cancer.

DIAGNOSIS

A number of blood tests are available to diagnose and monitor people with Hepatitis B They can be used to distinguish acute and chronic infections. Laboratory diagnosis of Hepatitis B infection centers on the detection of the Hepatitis B surface antigen HBsAg. A positive test for the Hepatitis B surface antigen.

(HBsAg) indicate that the person has an active infection (either acute or chronic) WHO recommends that all blood donations are tested for this marker to avoid transmission to recipients. Other commonly used test include the following:

•          testing for antibodies to the Hepatitis B surface antigen – a positive test indicates that the person has either recovered from an acute infection and cleared the virus, or has received a Hepatitis B vaccine. The person is immune to future Hepatitis B infection and is no longer contagious.

•          testing for antibodies to the Hepatitis B core antigen – a positive test indicates that the person has had a recent infection or an infection in the past. Combined with a positive test for the Hepatitis B surface antigen, a positive test usually indicates a chronic infection.

TREATMENT

There is no specific treatment for acute Hepatitis B. Care is aimed at maintaining comfort and adequate nutritional balance, including replacement of fluids that are lost from vomiting and diarrhoea.

•          Some people with chronic Hepatitis B can be treated with drugs, including interferon and antiviral agents. Treatment can cost thousands of dollars per year and is not available to most people in developing countries.

•          Liver cancer is almost always fatal and often develops in people at an age when they are most productive and have family responsibilities. In developing countries, most people with liver cancer die within months of diagnosis. In high-income countries, surgery and chemotherapy can prolong life for up to a few years.

•          People with cirrhosis are sometimes given liver transplants, with varying success.

PREVENTION

The Hepatitis B vaccine is the main-stay of Hepatitis B prevention. WHO recommends that all infants receive the Hepatitis B vaccine. The vaccine can be given as either three or four separate doses, as part of existing routine immunization schedules. In areas where mother-to-infant spread of the Hepatitis B virus is common, the first dose of vaccine should be given as soon as possible after birth (i.e. within 24 hours). The complete vaccine series induces protective antibody levels in more than 95% of infants, children and young adults. Protection lasts at least 20 years and is possibly lifelong. All children and adolescents younger than 18 years old and not previously vaccinated should receive the vaccine. People in high risk groups should also be vaccinated, including:

•          people with high-risk sexual behaviour

•          partners and household contacts of infected people

•          injecting drug users

•          people who frequently require blood or blood products

•          recipients of solid organ transplantation

•          people at occupational risk of Hepatitis B virus infection, including health-care workers

•          travellers to countries with high rates of Hepatitis B.

CONCLUSION

Although Hepatitis B may result in very fatal conditions, the good news is that infection with the virus is usually preventable because there is an effective vaccine. Use of the vaccine has resulted in an 82% decrease in the number of new infections reported in the United States each year.

REFERENCES

1.        Hepatitis BFact sheet N°204 July 2012 http://www.who.int/mediacentre/factsheets /fs204/ en/

2.        Hepatitis B (HBV, Hep B) http://www.emedicinehealth.com/hepatitis_b/article_em.htm

3.        Hepatitis B http://en.wikipedia.org/wiki/Hepatitis B

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