Common Types of Viral Hepatitis
What are the Common Types of Viral Hepatitis?
Although the most common types of viral hepatitis are HAV, HBV and HCV, some clinicians had previously considered the acute and chronic phases of hepatic infections as "types" of viral hepatitis
HAV was considered to be acute viral hepatitis because the HAV infections seldom caused or permanent liver damage that led to hepatic (liver) failure. HBV and HCV produced chronic viral hepatitis.
However, these terms are outdated and not currently used as frequently because all of the viruses that cause hepatitis may have acute phase symptoms. Prevention techniques and vaccinations have markedly reduced the current incidence of common viral hepatitis infections; however, there remains a population of about 800,000 to 1.4 million people in the U.S. with chronic HBV, and about 2.9 to 3.7 million with chronic HCV according to the CDC. Statistics are incomplete for determining how many new infections occur each year; the CDC documented infections but then goes on to estimate the actual numbers by further estimating the number of unreported infections.
Hepatitis A (HAV) :
HAV accounts for an estimated 1,781 new infections per year according to the most recent CDC data. The hepatitis caused by HAV is an acute illness (acute viral hepatitis) that never becomes chronic. At one time, hepatitis A was referred to as "infectious hepatitis" because it could be spread easily from person to person like other viral infections. Infection with hepatitis A virus can be spread through the ingestion of food or water, especially where unsanitary conditions allow water or food to become contaminated by human waste containing hepatitis A (the fecal-oral mode of transmission). Hepatitis A typically is spread among household members and close contacts through the passage of oral secretions (intimate kissing) or stool (poor hand washing). It also is common to have infection spread to customers in restaurants and among children and workers in day care centers if hand washing and sanitary precautions are not observed.
Hepatitis B (HBV) :
There were a more than 19,000 new cases of HBV infection estimated by the CDC in 2013 and more than 1,800 people die each year due to the consequences of chronic hepatitis B infection in the United States according to the CDC. HBV hepatitis was at one time referred to as "serum hepatitis," because it was thought that the only way HBV could spread was through blood or serum (the liquid portion of blood) containing the virus. It is now known that HBV can spread by sexual contact, the transfer of blood or serum through shared needles in drug abusers, accidental needle sticks with needles contaminated with infected blood, blood transfusions, hemodialysis, and by infected mothers to their newborns. The infection also can be spread by tattooing, body piercing, and sharing razors and toothbrushes (if there is contamination with infected blood). About 6% to 10% of patients with HBV hepatitis develop chronic HBV infection (infection lasting at least six months and often years to decades)
Hepatitis C (HCV) :
The CDC reported that there were about 16,500 reported new cases per year (unreported is 13.4 times more than reported) of hepatitis C. HCV hepatitis was previously referred to as "non-A, non-B hepatitis," because the causative virus had not been identified, but it was known to be neither HAV nor HBV. HCV usually is spread by shared needles among drug abusers, blood transfusion, hemodialysis, and needle sticks. Approximately 90% of transfusion-associated hepatitis is caused by HCV. Transmission of the virus by sexual contact has been reported, but is considered rare. An estimated 50% to 70% of patients with acute HCV infection develop chronic infection.
Types D, E, and G Hepatitis :
There also are viral hepatitis types D, E, and G. The most important of these at present is the hepatitis D virus (HDV), also known as the delta virus or agent. It is a small virus that requires concomitant infection with HBV to survive. HDV cannot survive on its own because it requires a protein that the HBV makes (the envelope protein, also called surface antigen) to enable it to infect liver cells. The ways in which HDV is spread are by shared needles among drug abusers, contaminated blood, and by sexual contact; essentially the same ways as HBV.
Individuals who already have chronic HBV infection can acquire HDV infection at the same time as they acquire the HBV infection, or at a later time. Those with chronic hepatitis due to HBV and HDV develop cirrhosis (severe liver scarring) rapidly. Moreover, the combination of HDV and HBV virus infection is very difficult to treat.
Hepatitis E virus (HEV) is similar to HAV in terms of disease, and mainly occurs in Asia where it is transmitted by contaminated water.
Hepatitis G virus (HGV, also termed GBV-C) was recently discovered and resembles HCV, but more closely, the flaviviruses; the virus and its effects are under investigation, and its role in causing disease in humans is unclear.
Who is at Risk for Viral Hepatitis?
People who are most at risk for developing viral hepatitis are:
- Workers in the health care professions
- Asians and Pacific Islanders
- Sewage and water treatment workers
- People with multiple sexual partners
- Intravenous drug users
- HIV patients
- People with hemophilia who receive blood clotting factors
Blood transfusion, once a common means of spreading viral hepatitis, now is a rare cause of hepatitis. Viral hepatitis is generally thought to be as much as ten times more common among lower socioeconomic and poorly educated individuals. About one third of all cases of hepatitis come from an unknown or unidentifiable source. This means that a person does not have to be in a high risk group in order to be infected with a hepatitis virus. In countries with poor sanitation, food and water contamination with HAV increases risk. Some day care centers may become contaminated with HAV, so children at such centers are at a higher risk for HAV infections.
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