Infection: Hepatitis B
Infection: Hepatitis B
Hepatitis B is a viral infection of the liver transmitted through the blood or body fluids of someone who is infected. It is the most common serious liver infection worldwide. The disease has two forms: an acute form that lasts a few weeks, and a chronic form that can last for years and can lead to cirrhosis, liver failure, liver cancer, and even death. Acute hepatitis B has a 5 percent chance of leading to the chronic form of the infection in adults; however, infants infected during the mother's pregnancy have a 90 percent chance of developing chronic hepatitis B, and children have a25–50 percent chance.
About two-thirds of people with chronic HBV infection are so-called “healthy” carriers of the virus. They may never get sick themselves but they can transmit the infection to others. The remaining one-third of people with chronic hepatitis B develop liver disease that can lead to permanent scarring of the liver. Between 15 and 25 percent of people with chronic hepatitis B eventually die of liver disease.
Hepatitis B has an incubation period of one to six months. About 50 percent of people with the acute form of the disease have no symptoms at all; the others experience loss of appetite, nausea and vomiting, and jaundice around twelve weeks after getting infected. Some patients may also have joint pain, itchy skin, or abdominal pain. Many of these patients assume that they have influenza.
Patients with chronic hepatitis may have no symptoms at all. The one-third who do eventually fall ill have the same symptoms as patients with the acute form of the disease.
People who have been infected by HBV and have recovered from the infection are protected against hepatitis B for the rest of their lives. People can also be protected by receiving a vaccine against the virus.
There are about 200,000 new cases of hepatitis B in the United States each year; it is estimated that 1–1.25 million people carry the disease.
Hepatitis B causes about 5,100 deaths in the United States each year. In the rest of the world, as many as a third of the population are chronic carriers of the disease.
The age group most commonly affected by hepatitis B in the United States is adults between the ages of twenty and fifty. African Americans are more likely to be infected than either Hispanics or Caucasians; however, Alaskan Eskimos and Pacific Islanders have higher rates of carrier status than members of other racial groups. More males than females are infected with hepatitis B in all races and age groups.
Risk factors for hepatitis B include:
- Having unprotected sex with a partner regardless of sexual orientation.
- Having a large number of sexual partners.
- Being infected with another sexually transmitted disease (STD), particularly gonorrhea or chlamydia.
- Sharing needles with other intravenous drug users.
- Having a family member with chronic HBV infection.
- Having had a blood transfusion or use of blood products before 1972.
- Needing hemodialysis for kidney disease.
- Frequent travels to parts of the world with high rates of hepatitis B. These include the Middle East, southern Africa, Southeast Asia, Brazil, and the Pacific Islands.
- Working in a hospital, clinic, or other facility requiring frequent exposure to blood, open wounds, or other body secretions.
Hepatitis B is caused by a virus. It is primarily a bloodborne infection, but can also be transmitted through contact with the semen or saliva of an infected person. The virus enters the body through injection, a break in the skin, or contact with the mucous membranes, tissues that line the mouth, genitals, and rectum. People cannot get hepatitis B from food or
from shaking hands, sneezing or coughing, breastfeeding, or casual contact with an infected person.
The symptoms of acute hepatitis B infection include:
- Loss of appetite
- Feeling tired
- Muscle and joint aches
- Low-grade fever
- Abdominal pain in the area below the rib cage
- Yellowish discoloration of the skin and whites of the eyes
- Tea- or cola-colored urine
- Grayish or clay-colored stools
A few people develop a severe form of hepatitis B known as fulminant hepatitis. This form of the disease appears rapidly and can cause death. Its symptoms include:
- Sudden collapse
- Mental confusion, hallucinations, or extreme sleepiness
- Noticeable swelling of the abdomen
Hepatitis B is diagnosed by one or more blood tests, since patients may not have any apparent symptoms. In a number of cases, the person is diagnosed following a routine blood test given as part of an annual health checkup. The most common clue is abnormal liver function results.
Hepatitis D, or delta hepatitis, is a liver disease caused by a virus (HDV) unrelated to the viruses that cause hepatitis A, B, and C. HDV is sometimes called the delta agent. Discovered only in 1977, the hepatitis D virus can replicate (multiply) only in patients infected with HBV. As of 2008 HDV infection was found in about 5 percent of patients diagnosed with hepatitis B. Hepatitis D can range from an acute, but limited, infection to a sudden, severe disease that leads to liver failure in 1 percent of patients. Most patients who are infected with hepatitis D alongside hepatitis B eventually get better. Chronic infection with both viruses occurs in only 5 percent of patients.
The World Health Organization (WHO) estimates that there are about fifteen million people worldwide infected with HDV. In the United States, hepatitis D is primarily a disease of adults rather than children. Risk factors include intravenous drug use and coming from southern Italy or other countries around the Mediterranean Sea.
HDV infection produces the same symptoms as hepatitis B. It can be detected by a blood test known as the anti-delta agent antibody test. Treatment is the same as for hepatitis B.
To confirm the diagnosis, the doctor will take one or more blood samples for testing:
- A test of liver function, if this has not already been done.
- Tests for antibodies to the hepatitis B virus. A positive result means that the person has either been effectively vaccinated against HBV or has been infected at some point in the past and has recovered.
- Tests for the surface antigen of the hepatitis B virus (HBsAg). The surface antigen is the outer coating of the virus. A positive HBsAg test means that the patient is currently infected and may be able to pass on the virus to others.
- Hepatitis B DNA test. This blood test measures the levels of virus in the patient's blood.
Patients with chronic active hepatitis B may be given a computed tomography (CT) scan or ultrasound of the liver to see whether the liver has been damaged by the infection. The doctor may also perform a liver biopsy. This test involves inserting a long hollow needle into the patient's liver through the abdomen and withdrawing a small amount of tissue for examination under a microscope.
Patients who know that they have been exposed to the hepatitis B virus can be treated by administering an immune-boosting injection and three shots of the HBV vaccine to prevent them from developing an active infection. Those who have already developed symptoms of the acute form of the disease may be given intravenous fluids to prevent dehydration or anti-nausea medications to stop vomiting. To date, there is no medication that can prevent acute hepatitis B from becoming chronic once the symptoms begin.
There are few treatment options for chronic hepatitis B. If the patient has no symptoms and little sign of liver damage, the doctor may suggest monitoring the levels of HBV in the patient's blood periodically rather than starting treatment right away. There are five different drugs used to treat hepatitis B, but they do not work in all patients and may produce severe side effects. Most doctors will wait until the patient'sliver function begins to worsen before administering these drugs.
If the patient develops fulminant hepatitis B or their liver is otherwise severely damaged by HBV, the only option is a liver transplant. This is a serious operation with a lengthy recovery period; its success also depends on finding a suitable donor liver.
Patients with acute hepatitis B usually recover; the symptoms go away in two to three weeks, and the liver itself returns to normal in about four
months. Other patients have a longer period of illness with very slow improvement. Chronic hepatitis leads to an increased risk of cirrhosis and liver cancer, and eventual death in about 1 percent of cases.
Hepatitis B can be prevented by vaccination with a vaccine called Engerix-B. The person receives the first two doses of the vaccine a month apart and the third dose six months later. The vaccine is recommended for all persons under the age of twenty; it can be given to newborns and infants as part of their regular vaccination series. Others who should be vaccinated include health care workers, military personnel, firefighters and police, people who travel frequently to countries with high rates of hepatitis B, people with hemophilia, people who must be treated for kidney disease, people who inject illegal drugs, and men who have sex with other men.
Other preventive measures include:
- Practicing safe sex
- Not sharing needles, razors, toothbrushes, or any other personal item that might have blood on it
- Avoiding getting a tattoo or body piercing, as some people who perform these procedures do not sterilize their needles and other equipment properly
- Getting tested for HBV infection if pregnant, as the virus can be transmitted from a mother to her unborn baby
- Consulting a doctor before taking an extended trip to any country with high rates of hepatitis B
The rate of hepatitis B in the United States began to drop after 1992, when vaccination of infants became routine, followed by vaccination of adolescents in 1995. Public health doctors expect the decline to continue for the foreseeable future.
Researchers at the National Institutes of Health (NIH) are presently looking for medications that will be effective in treating all patients with chronic hepatitis B with fewer side effects.
SEE ALSO Hemophilia; Hepatitis A; Hepatitis C
WORDS TO KNOW
Carrier: A person who is infected with a virus or other disease organism but does not develop the symptoms of the disease.
Chronic: Long-term or recurrent.
Cirrhosis: Disruption of normal liver function by the formation of scar tissue and nodules in the liver.
Fulminant: Referring to a disease that comes on suddenly with great severity.
Hepatitis: A general term for inflammation of the liver. It can be caused by toxic substances or alcohol as well as infections.
Jaundice: A yellowish discoloration of the skin and whites of the eyes caused by increased levels of bile pigments from the liver in the patient's blood.
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