Viral hepatitis (heh-puh-TIE-tus) is a disease in which liver function is impaired by a viral infection. There are three major types of viral hepatitis: hepatitis A, hepatitis B, and hepatitis C. Each of these forms of viral hepatitis is caused by a different virus.
An ailment in which liver function is impaired by a viral infection.
Incidence and Transmission
As reflected in the annual rate of new hepatitis infections, hepatitis B is the most common form of viral hepatitis in the United States, followed in order of frequency by hepatitis A and hepatitis C (Centers for Disease Control, 2009h). Each of these three varieties of hepatitis infection has declined substantially in incidence over the last 20 years (Holtzman, 2008). Although all three types of hepatitis can be transmitted through sexual contact, types A and B are more likely to be transmitted sexually than type C. Hepatitis B is transmitted more often through sexual activity than is hepatitis A. Sexual transmission among adults accounts for most hepatitis B infections in the United States (Centers for Disease Control, 2009h). Hepatitis A is a relatively common infection of young homosexual men, especially those who have multiple sex partners and those who engage in anal intercourse or oral-anal contact (Centers for Disease Control, 2009h; Des Jarlais et al., 2003). Furthermore, both hepatitis A and hepatitis B are often transmitted by means of needle sharing among injection drug users (Centers for Disease Control, 2009h).
Hepatitis B can be transmitted through blood or blood products, semen, vaginal secretions, and saliva (Torpy et al., 2011). An infected mother can transmit a hepatitis B infection to her baby at birth (Centers for Disease Control, 2009h). The CDC recommends that pregnant women be tested for hepatitis B. Manual, oral, or penile stimulation of the anus is strongly associated with the spread of this viral agent. Hepatitis A seems to be spread primarily through the fecal-oral route. Consequently, epidemics often occur when infected handlers of food do not wash their hands properly after using the bathroom. Oral-anal sexual contact seems to be a primary mode for sexual transmission of hepatitis A (Centers for Disease Control, 2009h).
Recently, health officials in the United States have focused considerable attention on the most health-threatening of the hepatitis viruses, hepatitis C, which is an emerging communicable disease of epidemic proportions (Centers for Disease Control, 2010b; Edlin, 2011). Over the last few years, hepatitis C has become a major global
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health problem, and it is now one of the most common chronic viral infections in North America. It is estimated that approximately 200 million people in the world have chronic hepatitis C infections—5 million of whom are in the United States (Centers for Disease Control, 2010b; Gravitz, 2011). People whose immune systems are deficient, such as HIV-infected individuals, are especially vulnerable to hepatitis C infections, which cause 12,000 deaths each year in the United States (Centers for Disease Control, 2010b).
Hepatitis C is transmitted most commonly through blood-contaminated needles shared by injection drug users (Centers for Disease Control, 2011b; Gravitz, 2011). Other, less common modes of transmission include transfusion of contaminated blood products, sexual contact, and perinatal transmission from an infected mother to her fetus or infant (Centers for Disease Control, 2009h). Whether transmission of hepatitis C through unprotected sexual intercourse is a significant factor in the spread of hepatitis C is debatable, but evidence indicates that some hepatitis C infections are sexually transmitted, especially among HIV-infected MSM (Centers for Disease Control, 2009h; Fierer et al., 2011; Montoya-Ferrer et al., 2011).