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| Hepatitis B (HBV) By Bruce Huynh |
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Abstract
The word hepatitis means inflammation of the liver, an irritation or swelling of the liver cells. Hepatitis B is a liver disease cause by hepatitis B virus (HBV). HBV is transmitted by exposure to the blood and body fluids of an infected person. Ultrasound is frequently used as a noninvasive diagnostic tool to assess and detect problems of the liver. Ultrasound can distinguish between various types of liver problems. In order to effectively use ultrasound in identifying liver diseases, an ultrasound technician must have a solid understanding of the causes of liver diseases such as Hepatitis B virus. |
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Keywords
Hepatitis, Hepatitis virus, Hepatitis B virus, HBV, Liver Diseases, Cirrhosis, Sexual Transmitted Disease (STD), hepatocellular carcinoma, liver cancer. |
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Introduction
There are very few known viruses in the world that have so many different variations as the Hepatitis virus. Currently, there are 7 different types of the virus: A, B, C, D, E, F, and G. There are differences as well as similarities among these viruses. One common factor is that they all attack the liver. Although hepatitis had been recognized for centuries, doctors had no idea what caused it until the 1940s when they came to suspect that a virus carried in human blood was responsible. Hepatitis B, or serum hepatitis, is caused by a type of hepatitis virus, called HBV. The liver is the largest organ in the body and it carries out many important functions, such as making bile, changing food into energy, and cleaning alcohol and poisons from the blood. When someone gets hepatitis the function of the liver is compromised and affected in many ways. If left untreated, it can be fatal. Fortunately, there is a vaccine for HBV. Therefore, early detection of the disease is very important in treating it. This paper will focus on Hepatitis B, which is a form that is transmitted mainly by exposure to contaminated blood and body fluid, and discuss its effects, such as infection patterns, diagnostics, treatments, and prevention. |
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| Normal Liver |
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Body
Although the main cause of hepatitis is the hepatitis virus, other types of virus, such as Yellow Fever, Epstien Bar virus (EBV, member of herpes family), and Cytomegalovirus (CMV, member of herpes virus) can cause hepatitis as a secondary effect. There are two types of hepatitis infection, acute and chronic. When a person is first infected with the hepatitis B virus, this is called an acute infection. If the HBV virus remains in the system for more than 6 months, it is then considered chronic. Chronic hepatitis B is the most common serious liver infection in the world 1. An acute hepatitis B infection can progress to chronic condition, which result in cirrhosis, liver cancer, liver failure, and death if treatments are not administered. Moreover, individual with chronic hepatitis B infection, especially those with cirrhosis are at an increased risk to develop hepatocellular carcinoma (primary liver cancer). This cancer is relatively rare in the United States, but it is the leading cause of cancer in the world, especially in the East where HBV infection is high 2.
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Methods of Transmission
Hepatitis B can transmit both vertically and horizontally. Horizontal transmission is between peers. Vertical transmission is between infected mothers and their newborns 2. Hepatitis B is considered a sexually transmitted disease. As such, it can be transmitted the same ways as STDs. The most common method of transmission is through the exchange of fluids such as blood, semen, breast milk, and in some rare circumstances, saliva1. Some common paths of transmission are people that have unprotected sexual intercourse with infected parties; people share needles and syringes in activities such as drugs, tattoos, and piercing; babies born to infected mothers; healthcare workers and patients receiving hemodialysis; and sharing of personal items such as razors and toothbrushes5. Many cases of acute hepatitis B have known to occur sporadically with no known source. |
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Symptoms
Many people who are infected with acute Hepatitis B and show no symptoms. About 90 percent of adults who got infected with HBV will recover and produce antibodies to combat future infections. The remaining 10 percent will develop some common symptoms such as jaundice (yellowing of the eye and skin), extreme fatigue, abdominal pain, loss of appetite, nausea and vomiting, fever, muscle aches, and headaches. Other symptoms are dark brown urine and discomfort under the right rib cage 4&5. |
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| Transverse and sagittal ultrasound images show an HCC in a cirrhotic liver. |
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Diagnosis
There are a few tests that can be used to detect the presence of HBV virus. The first test, antibody to hepatitis B core antigen (anti-HBc), is the most common one. This test is used to determine if vaccination is necessary. The next test is to look for Hepatitis B surface antigen (HBsAg). This antigen is the earliest indicator of acute Hepatitis B infections. The Hepatitis B e-antigen (HBeAg) is found in the blood only when the HBV virus is present. When the HBV virus goes into hiding, HBeAG can not be detected in the blood. HBeAG is usually performed to measure the effectiveness of a treatment. These two tests can be carried out with blood samples. In addition to the blood test, there is alpha-fetoprotein (AFP, Protein often found in abnormal amounts in the blood of patients with liver cancer), ultrasound scan, and liver biopsy. The latter ones are used to detect possible liver damage. In his “Guidelines for the diagnosis and treatment of hepatocellular carcinoma (HCC) in adults”, Dr Snyder suggested that surveillance using abdominal ultrasound and alpha-fetoprotein (AFP, Protein often found in abnormal amounts in the blood of patients with liver cancer) estimation can detect HCC of a smaller size than those presenting without screening, especially in high risk individuals with established cirrhosis due to hepatitis B virus7. In a case study done by Wun and Kickenson8, the authors compared bi-annual screening with alpha-fetoprotein plus ultrasound against no screening for five years. The result was more liver cancers were detected in the screened group. |
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Geographic Prevalence of HBV Infections
Currently, there are 400 million people worldwide are chronically infected with hepatitis B — 280 million of those are Asians/Pacific Islanders (APIs). It is estimated that 1.25 million people have chronic hepatitis B in the United States, and Asian Americans account for more than half of the cases. As many as 1 out of 10 Asian Americans has chronic hepatitis B. 15 to 25 percent of people with chronic hepatitis B will eventually die from liver disease without treatment. Worldwide, chronic hepatitis B is the leading cause of liver cancer and is the sixth leading cause of liver transplantation. Hepatitis B is 50 to 100 times more contagious than HIV (the virus that causes AIDS)4. |
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Treatments Available
Vaccines exist for hepatitis infections. The vaccines provide antibodies against HBsAg, the same way individuals that are immune against HBV 2. There are drugs to treat chronic infected individuals. Current consensus guidelines from Asia, Europe, and the United States recommend lamivudine, adefovir, or conventional interferon Alfa. According to a case study published in New England Journal of Medicine, in patients with HBeAg-positive chronic hepatitis B, peginterferon alfa-2a offers superior effectiveness over lamivudine, on the basis of HBeAg seroconversion, HBV DNA suppression, and HBsAg seroconversion 6. Interferon alpha must be administered for 16 weeks. The treatment decreases viral replication, as supported by the loss of serum hepatitis B antigen in about 45 percent of treated patients. Within one year of treatment, 8 percent is considered “cured” compared to 1 percent of untreated patients6. Death from chronic liver disease without vaccination occurs in 15-25% of chronically infected persons5. |
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Prevention
A large number of people worldwide are carriers, meaning their immune systems tolerate the virus and do not see it as foreign. Carriers do not have any symptoms for many decades but can unknowingly infect other people. Fortunately, following the prevention methods recommended by the CDC for Hepatitis B should minimize one’s risk of contracting the virus. First, get Hepatitis B vaccination because it is the best protection. Second, if you are having sex, but not with one steady partner, use latex condoms correctly and every time you have sex. Third, if you are pregnant, you should get a blood test for hepatitis B; Infants born to HBV-infected mothers should be given HBIG (hepatitis B immune globulin) and vaccine within 12 hours after birth. Fourth, do not shoot drugs; if you shoot drugs, stop and get into a treatment program; if you can't stop, never share drugs, needles, syringes, water, or "works", and get vaccinated against hepatitis A and B. Fifth, do not share personal care items that might have blood on them (razors, toothbrushes). Sixth, consider the risks if you are thinking about getting a tattoo or body piercing. You might get infected if the tools have someone else's blood on them or if the artist or piercer does not follow good health practices. Seventh, if you have or had hepatitis B, do not donate blood, organs, or tissue. Finally, if you are a health care or public safety worker, get vaccinated against hepatitis B, and always follow routine barrier precautions and safely handle needles and other sharps 5. |
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Conclusion
The hepatitis B virus is probably the most common cause of cirrhosis worldwide (less common in the United States and the Western world). Cirrhosis of the liver result in scar tissue replaces healthy tissue and blocks the flow of blood through the organ and preventing it from working as it should. One detection method is ultrasound. This is a non invasive method of assessing liver health. It can differentiate between many of the types and causes of liver malfunction, and it is particularly good at identifying cirrhosis, which is characterized by abnormal fibrous growths and altered blood flow. Liver damage from cirrhosis is irreversible, but treatment can stop or delay further damage and reduce complications3. Therefore, early detection is very important. It is recommended that individuals who are in the high risk categories should take Hepatitis B vaccine. In addition, they should have their liver function test and ultrasound scan of their liver twice yearly. |
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Bibliography
1. Millinship, Stuart, “Hepatitis B (HBV) Overview”, (http://www.hon.ch/Hepatitis/HBV_Chap1-3.html#whatis_hep
2. Worman, J. Howard, M. D., “Hepatitis B”, http://cpmcnet.columbia.edu/dept/gi/hepB.html)
3. “Cirrhosis of the Liver”. NIH Publication No. 04–1134. December 2003 http://digestive.niddk.nih.gov/ddiseases/pubs/cirrhosis/index.htm
4. Statistics. www.stophepb.com by Gilead Sciences
5. “Hepatitis B Factsheet”, National Center for Infectious Disease. (http://www.cdc.gov/ncidod/diseases/hepatitis/b/)
6. George K.K. Lau, M.D., et al. “Peginterferon Alfa-2a, Lamivudine, and the Combination for HBeAg-Positive Chronic Hepatitis B”, The New England Journal of Medicine. June 30, 2005, Vol 352;26
7. Ryder, S D, “Guidelines for the diagnosis and treatment of hepatocellular carcinoma (HCC) in adults”. Gut, May 2003; 52: 1 – 8
8. Wun, YT, Dickinson, JA. "Alpha-fetoprotein and/or liver ultrasonography for liver cancer screening in patients with chronic hepatitis B", The Cochrane Database of Systematic Reviews. 2006 Issue 1.
9. "Abdominal Ultrasound." Encyclopedia of Surgery. Ed. Anthony J. Senagore. Thomson Gale, 2004. eNotes.com. 2006. 1 Mar, 2006 10. http://health.enotes.com/surgery-encyclopedia/abdominal-ultrasoundhttp://www.droid.cuhk.edu.hk/web/service/ultrasound/usdiagnostic.htm#1 11. http://www.massgeneralimaging.org/newsletter/january_2005/
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