6 Mayıs 2008 Salı

Hepatitis



You've probably heard warnings about hepatitis, a category of viral infections that can cause serious liver damage and even lead to death. Hepatitis literally means inflammation of the liver (hepa = liver; it is = inflammation).
If you're having trouble keeping up with the alphabet soup of the different types of the virus you're not alone. There are six main types: A, B, C, D, E and G. For the most part, however, you need to concern yourself only with hepatitis A virus, hepatitis B virus and hepatitis C virus-referred to as HAV, HBV and HCV respectively.
The hepatitis viruses all cause acute inflammation of the liver, while some infections related to hepatitis B and C may become chronic. Although many hepatitis infections do not cause symptoms, in those that do, the leading symptoms are:
jaundice (yellowing of the skin and eyes)
fatigue, malaise
abdominal pain
appetite loss
nausea
diarrhea
vomiting
The good news is that vaccines against hepatitis A and hepatitis B have been introduced in the last 20 years. The U.S. Centers for Disease Control and Prevention (CDC) recommends that all children under 18 be vaccinated against hepatitis B (HBV), and that those at risk for either infection get the appropriate vaccination.
Hepatitis AHepatitis A, or HAV, causes about one third of all cases of acute hepatitis in the U.S., During epidemic years, the number of reported cases reached 35,000. In the late 1990s, hepatitis A vaccine was more widely used and the number of cases reached historic lows. However, health officials believe it is underreported because people often have no symptoms. HAV infection causes temporary symptoms and is not associated with chronic liver disease. Once you have had HAV you cannot get it again, although about 15 percent of people infected with the virus have prolonged or relapsing symptoms over a six to nine month period, according to the CDC.
HAV receives attention usually because of community outbreaks that result from person-to-person transmission, primarily through daycares and contact with contaminated food or water. In fact, the FDA recently (Nov. 2003) issued a warning advising the public that several recent hepatitis A outbreaks have been associated with eating raw or undercooked green onions (scallions) and offered the following advice to consumers:
Cook green onions thoroughly. This minimizes the risk of illness by reducing or eliminating the virus. Cook in a casserole or sauté in a skillet.
Check food purchased at restaurants and delicatessens and ask whether menu items contain raw or lightly cooked green onions. Consumers who wish to avoid food that contains raw or lightly cooked green onions should specifically request that raw or lightly cooked green onions not be added to their food. Foods such as freshly prepared salsa and green salads often contain raw green onions.
For most women, the biggest risk factors are sexual or household contact with an infected person, or travel to countries where hepatitis A is common. You cannot get the infection through casual contact.
For hepatitis A, vaccination is recommended for the following persons:
Children two years of age and older
Travelers to areas with increased rates of hepatitis A (view map, see below for link)
Men who have sex with men
Injecting and non-injecting drug users
Persons with clotting-factor disorders (e.g., hemophilia)
Persons with chronic liver disease
Children living in regions of the U.S. with consistently increased rates of hepatitis A (including much of the West, Southwest and Alaska.) Here's a link to a map showing geographic risk: View map of geographic risk
Hepatitis BHepatitis B vaccines have been available since 1982 and, as a result, the number of new infections per year has declined from an average of 260,000 in the 1980s to about 78,000 in 2001, according to the CDC. Approximately 1.25 million people are chronically infected with HBV in the U.S., of whom 20 to 30 percent acquired their infection in childhood. Death from chronic liver disease occurs in 15-25 percent of chronically infected persons. One leading mode of transmission is unsafe sex. The virus is also spread by shared needles, from a mother to her newborn, between children in daycare settings, and in health care settings. Screening of blood donors has virtually eliminated transmission via blood transfusion. All pregnant women in the US should be screened for hepatitis B. If infected, the baby will need to receive specific hepatitis B immune globulin and be vaccinated at birth.
Vaccination against hepatitis B is also recommended for:
All children under age 18
Persons with multiple sex partners or diagnosis of a sexually transmitted disease
Men who have sex with men
Sex contacts of infected persons
Injection drug users
Household contacts of chronically infected persons
Infants born to infected mothers
Infants/children of immigrants from areas with high rates of HBV infection
Health care and public safety workers
Hemodialysis patients
Patients with other liver diseases
Hepatitis CHepatitis C, or HCV, has been the focus of recent attention because an estimated 3.9 million Americans are believed to have been exposed and 2.7 million are chronically infected. Hepatitis C causes up to 10,000 deaths a year, due to complications of cirrhosis and liver cancer. Treatments are available but they are not effective in all patients. Most infections occurred in the 1970s and 1980s from contaminated blood used during transfusions and from injection drug use. The virus was first identified in 1988 and, in 1989, a reliable test was developed that could identify antibodies to the virus in blood supplies. Today, using more sensitive and specific antibody tests and RNA testing there is less than one case of HCV infection per million units of transfused blood.
HCV poses serious health problems for some people while for others there may be no long-term consequences. Natural history studies suggest that the rate of progression to cirrhosis (scarring of the liver) is highly variable, ranging from 0.5 to 25 percent of patients with chronic disease who have had the infection for 10 to 30 years. Liver cancer develops in approximately 2 percent of cirrhotic patients each year.
Although the annual number of new HCV infections has decreased dramatically-from a high of 240,000 in the 1980s to 25,000 in 2001-most infected people don't know they have the virus. Only recently have health officials made a concerted effort to notify those who received blood or blood products contaminated with HCV before routine screening began.
Testing for hepatitis C by detection of a specific antibody for the virus is recommended for injection drug users, recipients of blood clotting factors, hemodialysis patients, recipients of blood transfusions or solid organ transplants before 1992 and infants born to infected mothers (after 12 to 18 months).
Hepatitis DHepatitis D virus, or HDV, is uncommon, except in IV drug users. It can lead to cirrhosis in up to 70 percent of cases, often within a few years. HDV, acquired through contact with infected blood, occurs only in those already infected with hepatitis B. Also at risk are those with HBV who have sex or live with a person infected with HDV. For those not infected with HBV, a vaccine can shield them from that virus and therefore provide protection against HDV as well.
Hepatitis EHepatitis E virus, or HEV, is similar to hepatitis A virus in mode of transmission and the duration of the disease, although it tends to occur as part of large water- or food-borne epidemics. HEV spreads through contact with food or water contaminated by feces from an infected person. Rare in the U.S., the infection usually clears up after several weeks to a few months. At risk are international travelers, people living in areas where HEV outbreaks are common and people who have sex or live with an infected person. Pregnant women infected with HEV have a 20 percent risk of dying. To limit risk of HEV exposure, avoid tap water when traveling internationally and practice good hygiene and sanitation.

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