Hepatitis  Overview

Hepatitis is a general term that means inflammation of the liver. Inflammation of the liver can result from infection, from exposure to alcohol, certain medications, chemicals, or poisons, or from a disorder of the immune system.

Hepatitis is most commonly caused by one of three viruses:
1.      the hepatitis A virus
2.      the hepatitis B virus
3.      the hepatitis C virus

In some rare cases, the Epstein Barr Virus (which causesmononucleosis) can also result in hepatitis because it can cause inflammation of the liver. Other viruses and bacteria that also can cause hepatitis include hepatitis D and E, chickenpox, andcytomegalovirus (CMV).

Hepatitis A
In children, the most common form of hepatitis is hepatitis A (also called infectious hepatitis). This form is caused by the hepatitis A virus (HAV), which lives in the stools (feces or poop) of infected individuals. Infected stool can be present in small amounts in food and on objects (from doorknobs to diapers).

HAV is spread:
• when someone ingests anything that's contaminated with HAV-infected stool (this makes it easy for the virus to spread in overcrowded, unsanitary living conditions)
• in water, milk, and foods, especially in shellfish
Because hepatitis A can be a mild infection, particularly in children, it's possible for some people to be unaware that they have had the illness. In fact, although medical tests show that about 40% of urban Americans have had hepatitis A, only about 5% recall being sick. Although the hepatitis A virus can cause prolonged illness up to 6 months, it typically only causes short-lived illnesses and it does not cause chronic liver disease.

Hepatitis B
Hepatitis B (also called serum hepatitis) is caused by the hepatitis B virus (HBV). HBV can cause a wide spectrum of symptoms ranging from general malaise to chronic liver disease that can lead to liver cancer.
HBV spreads through:
• infected body fluids, such as blood, saliva, semen, vaginal fluids, tears, and urine
• a contaminated blood transfusion (uncommon in the United States)
• shared contaminated needles or syringes for injecting drugs
• sexual activity with an HBV-infected person
• transmission from HBV-infected mothers to their new born babies.

Hepatitis C
The hepatitis C virus (HCV) is spread by direct contact with an infected person's blood. The symptoms of the hepatitis C virus can be very similar to those of the hepatitis A and B viruses. However, infection with HCV can lead to chronic liver disease and is the leading reason for liver transplant in the United States.
The hepatitis C virus can be spread by:
• sharing drug needles.
• getting a tattoo or body piercing with unsterilized tools
• blood transfusions (especially ones that occurred before 1992; since then the U.S. blood supply has been routinely screened for the disease)• transmission from mother to newborn
• sexual contact (although this is less common)
Hepatitis C is also a common threat in kidney dialysis centers. Rarely, people living with an infected person can contract the disease by sharing items that might contain that person's blood, such as razors or toothbrushes.

* People who are infected can start spreading the infection about 1 week after their own exposure. People who do not have symptoms can still spread the virus. Infection with HAV is known to occur throughout the world.

•  The risk of infection is greatest in developing countries with poor sanitation or poor personal hygiene standards.
   
• Infection rates are also higher in areas where direct fecal-oral transmission is likely to occur, such as daycare centers, prisons, and mental institutions.

* People at increased risk for hepatitis A infection

• Household contacts of people infected with HAV
• Sexual partners of people infected with HAV
• International travelers, especially to developing countries
• Military personnel stationed abroad, especially in developing countries
• Men who have sex with other men
• Users of illegal drugs (injected or non-injected)
• People who may come into contact with HAV at work

* Workers in professions such as health care, food preparation, and sewage and waste water management are not at greater risk of infection than the general public.

* People who live or work in close quarters, such as dormitories, prisons, and residential facilities, or work in or attend daycare facilities are at increased risk only if strict personal hygiene measures are not observed.