Hepatitis

The liver's location in the right upper abdomen. Source: NIDDK

Types

Major Causes of Hepatitis. Source: CDC.

• Viral infection of the liver (viral hepatitis)
• Overexposure to damaging chemicals (toxins) such as alcohol or acetaminophen (Tylenol)
• Non-viral infections such as syphilis, Q fever, or Leptospirosis
• Metabolic disorders
• Immune system dysfunction
• Decreased blood flow to the liver
• Blockage of the bile tract
• Other rare causes such as Wilson's disease, tumor infiltration of the liver, or sickle cell disease

Viral infections of the liver are the most common cause of hepatitis; these include:

• Hepatitis A virus (HAV)
• Hepatitis B virus (HBV)
• Hepatitis C virus (HCV)
• Hepatitis D virus (requires infection with Hepatitis B virus at the same time)
• Hepatitis E virus
• Hepatitis G virus (GBV-C)

The term "viral hepatitis" does not usually refer to disease caused by viruses listed below, which do not have a particular affinity for the liver as do the "hepatitis" viruses listed above. Viruses that cause systemic infections that may involve the liver include:

• Mumps, rubella, rubeola, coxsackie B, yellow fever, cytomegalovirus, and Epstein-Barr virus

Symptoms

Viral hepatitis typically presents in an acute form. Hepatitis caused by HBV, HCV or Hepatitis D virus can progress to a chronic form in which the liver suffers ongoing damage and scarring (cirrhosis).

Acute Hepatitis

Some people who develop hepatitis can have no symptoms (they are asymptomatic). Others can have varying degrees of illness, even a fulminant form that can lead to death. There are no specific symptoms that can help distinguish one form of hepatitis from another, or one cause from another.

Symptoms of acute hepatitis include the following:

• Tiredness
• Weakness
• Loss of appetite
• Nausea and vomiting
• Vague, dull pain or discomfort in the upper right abdomen
• Mild weight loss
• Jaundice - yellowing of the skin and the whites of the eyes
• Dark urine
• Fevers

Chronic Hepatitis

Most people who develop chronic hepatitis have no symptoms or very mild symptoms. They may have return of the symptoms associated with acute hepatitis. They may feel worse if they drink alcohol or take certain medications. They may experience fullness in the abdomen, recurrent fatigue, or development of an enlarged abdomen due to a build up of fluid (ascites). With progression of chronic hepatitis, the liver becomes increasingly scarred and unable to perform vital functions for the body. This can lead to severe weight loss, increased bleeding tendencies, easy bruising, malaise, varicose veins (both internally and externally) and debilitation.

Please refer to more in-depth information on the specific forms of hepatitis available in separate pages on this website.

Viral Hepatitis

The five hepatitis viruses discussed below have very little in common except for their affinity for setting up infections in the human liver. Up until the 1940s only two viruses were thought to account for all cases of viral hepatitis, but in the latter half of the 20th century, additional viruses have been discovered and characterized. The five viruses are quite different from one another in terms of structure and function, and infections result in different patterns of disease.

Hepatitis A

Hepatitis A, known simply as infectious hepatitis before the diversity of hepatitis-causing viruses was described, has been known since antiquity and probably caused epidemics of "campaign jaundice" among armies of the Middle Ages.^[1] It does not usually cause severe disease, nor does it cause long-lasting (chronic) infections or persist in the body. The fatality rate is very low (less than 0.1%), and immunization programs have resulted in impressive reductions in the number of cases. HAV immunization is recommended for children at the age of 12 to 23 months.^[2] There is hope that the disease may be eradicated some day, but efforts are complicated in some regions of the world by substandard hygiene and sanitation.

The virus is spread by ingestion of contaminated water and foods and is shed in the stool for about 2 to 3 weeks before and 1 week after the onset of symptoms. The stool from infected persons can be highly infective, with as many as one billion infectious doses per gram.^[3]Close personal contact with an infected individual accounts for most cases, explaining the outbreaks in settings such as schools and nurseries and the cases in overcrowded, unsanitary environments. In some cases, infections may be contracted by the consumption of shellfish (oysters, mussels, clams), which concentrate the virus from seawater contaminated with human sewage.^[4]

Hepatitis B

Hepatitis B (HBV) is the cause of "serum hepatitis" and can produce a wide range of symptoms and represents a large public health problem. More than 400 million people worldwide and over 1.25 million Americans have the chronic form of the disease.^[5] The liver damage caused by HBV may happen rapidly or over the course of years, or the virus may be present without causing any symptoms at all. The virus is an important cause of cirrhosis (replacement of parts of the liver with scar tissue) and hepatocellular carcinoma (cancer of the liver).

The virus is present in almost all cells and tissues of the body, meaning that the blood, body fluids, and secretions of infected individuals can transmit the infection. Accidental needle-sticks among health workers are a risk for transmission, as are unprotected sexual activity and sharing of intravenous needles and syringes. The virus can also be transmitted from an infected mother to her child. Immunization programs, such as one implemented for elementary school students in Hawaii,^[6] hold significant promise of reducing or eliminating the disease.

Hepatitis C

Hepatitis C (HCV) is another major cause of liver disease worldwide, and about 3 million people in the US and 17 million people worldwide are chronically infected. Before identification of the causative virus, the disease was known as "non-A, non-B hepatitis." Infections with HCV are usually persistent, and the liver damage caused by the virus progresses to cirrhosis in over 50% of the cases. The persistence and progressive disease make it the leading infectious cause of chronic liver disease in the Western world.^[7]

The virus mutates easily, and at least six major types of HCV have been identified. The virus is often transmitted by injection drug use^[8]; other behaviors identified as risk factors include intranasal cocaine use, body piercing, tattoos, and hemodialysis. Treatment of acute HCV infections with high-dose interferon alpha may help reduce the risk of progression to chronic HCV infection.^[9]

Hepatitis D

Hepatitis D virus (HDV), also known as the delta agent, is only a concern for people who are already infected by HBV. Infection with HDV can occur at the same time as HBV, or when HBV infection has become well-established. The virus was identified in the 1970s, when physicians isolated it from patients with unusually severe cases of HBV.^[10] Of the 300 million people worldwide who are infected with HBV, about 5% are also infected with HDV.

At-risk groups for HDV infection are similar for infection by other hepatitis viruses, and include people who receive blood transfusions (such as people with hemophilia), people who share syringes with infected individuals, and people who engage in unprotected sexual activity with infected individuals.

There are two possible patterns of infection with HDV, both of which require HBV: coinfection, when the viruses are encountered by the patient at the same time, and superinfection, when an HBV-infected person is later exposed to HDV. For patients who are coinfected, recovery is the rule; it may be that HDV interferes with HBV in some way. Superinfection is more dangerous—severe acute hepatitis develops in at least half of patients, and liver failure (resulting in the need for transplantation) is much more common.^[11] Although no vaccine for HDV exists, immunization strategies targeting HBV have the added benefit of reducing the burden of HDV disease as well.^[12]

Hepatitis E

Hepatitis E virus (HEV), like hepatitis A, is transmitted via the intestinal tract and generally causes an acute, self-limited illness that rarely causes serious damage to the liver and never results in chronic liver disease. Exposure is most often through contaminated drinking water, and the disease was previously known as water-borne hepatitis or enterically (meaning through the intestines) transmitted non-A, non-B hepatitis. The virus is notable for being especially dangerous to pregnant women, with mortality rates as high as 20% in some studies.^[13]

HEV disease is much more common in parts of the world with poor sanitation infrastructure; there have been no outbreaks in the US or Canada. The virus was characterized and named in 1990.^[14][15] It is not clear if having HEV once will confer resistance to later infections, and there is no vaccine currently available. There are many minor variants of HEV that cause disease, and, unlike other hepatitis viruses, HEV exists in animals and can be passed back and forth between different species.^[16]

Hepatitis G

Hepatitis G virus (HGV) is a distant relative of HCV and was first described in 1996. It is probably transmitted sexually or via needle-sticks, and there has been active discussion surrounding the role of the virus in disease, to the extent that some authors question whether HGV even causes hepatitis.^[17] Diagnosing HGV is complex and costly, and as is the case for all forms of acute hepatitis, there is no specific treatment for HGV-induced acute hepatitis.

References

1. ↑ Purcell RH. Hepatitis viruses: changing patterns of human disease. Proc Natl Acad Sci U S A. 1994 Mar 29;91(7):2401-6. [http//pubmed.gov/8146130 Abstract] | PDF
2. ↑ Advisory Committee on Immunization Practices (ACIP), Fiore AE, Wasley A, Bell BP. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2006 May 19;55(RR-7):1-23. Abstract | Full Text
3. ↑ Purcell RH, Feinstone SM, Ticehurst JR, Daemer RJ, Baroudy BM. (1984) In: Viral Hepatitis and Liver Disease, Vyas GN, Dienstag JL, Hoofnagle JH, eds. (Grune & Stratton, New York), pp. 9-22.
4. ↑ Brundage SC, Fitzpatrick AN. Hepatitis A. Am Fam Physician. 2006 Jun 15;73(12):2162-8. [1] | Full Text | PDF
5. ↑ Lin KW, Kirchner JT. Hepatitis B. Am Fam Physician. 2004 Jan 1;69(1):75-82. Abstract | Full Text | PDF
6. ↑ Perz JF, Elm JL Jr, Fiore AE, Huggler JI, Kuhnert WL, Effler PV. Near elimination of hepatitis B virus infections among Hawaii elementary school children after universal infant hepatitis B vaccination. Pediatrics. 2006 Oct;118(4):1403-8. Abstract | Full Text | PDF
7. ↑ Patel K, Muir AJ, McHutchison JG. Diagnosis and treatment of chronic hepatitis C infection. BMJ. 2006 Apr 29;332(7548):1013-7. Abstract | Full Text | PDF
8. ↑ Wong T, Lee SS. Hepatitis C: a review for primary care physicians. CMAJ. 2006 Feb 28;174(5):649-59. Abstract | Full Text | PDF
9. ↑ Pimstone NR, Pimstone D, Saicheur T, Powell J, Yu AS. "Wait-and-see": an alternative approach to managing acute hepatitis C with high-dose interferon-alpha monotherapy. Ann Intern Med. 2004 Sep 21;141(6):W91-2. Citation
10. ↑ Chatzinoff M, Friedman LS. Delta agent hepatitis. Infect Dis Clin North Am. 1987 Sep;1(3):529-45. Abstract
11. ↑ Hsieh TH, Liu CJ, Chen DS, Chen PJ. Natural course and treatment of hepatitis D virus infection. J Formos Med Assoc. 2006 Nov;105(11):869-81. Abstract | PDF
12. ↑ Koff RS. Hepatitis vaccines. Infect Dis Clin North Am. 2001 Mar;15(1):83-95. Abstract
13. ↑ Bradley DW, Maynard JE.Bradley DW, Maynard JE. Etiology and natural history of post-transfusion and enterically-transmitted non-A, non-B hepatitis. Semin Liver Dis. 1986 Feb;6(1):56-66.Citation
14. ↑ Reyes GR, Purdy MA, Kim JP, et al. Isolation of a cDNA from the virus responsible for enterically transmitted non-A, non-B hepatitis. Science. 1990 Mar 16;247(4948):1335-9. Abstract
15. ↑ Zuckerman AJ. Hepatitis E virus. BMJ. 1990 Jun 9;300(6738):1475-6. Citation | PDF
16. ↑ Mushahwar IK. Hepatitis E virus: molecular virology, clinical features, diagnosis, transmission, epidemiology, and prevention. J Med Virol. 2008 Apr;80(4):646-58. Abstract
17. ↑ Abe K. GB virus-C/hepatitis G virus. Jpn J Infect Dis. 2001 Apr;54(2):55-63. Abstract

External Links

World Hepatitis Alliance: World Hepatitis Awareness Day

American Liver Society

American Liver Foundation: Comprehensive information about hepatitis, including links to chapters for finding local resources

Children's Liver Disease Foundation

World Health Organization: Hepatitis

Centers for Disease Control and Prevention (CDC): Viral Hepatitis

U.S. Department of Veterans Affairs: National Hepatitis C Program