hepatitis
Highly magnified image of hepatitis B viruses.
Hepatitis is Inflammation of the liver. It can be caused by viruses, bacteria, parasites, autoimmune conditions, reactions to certain drugs, heavy alcohol use, and other toxins, but is usually due to a generalized infection. Early symptoms include lethargy, nausea, fever, jaundice, and muscle and joint pains.
Five different hepatitis viruses have come to light: A, B, C, D, and E, with different routes of transmission and different prognoses. . The commonest single cause, accounting for up to 40% of cases worldwide, is the hepatitis A virus (HAV), which colonizes the digestive tract, causing an acute illness. Much more serious is infection with the hepatitis B virus (HBV). Formerly known as serum hepatitis, it can lead to chronic inflammation of the liver and, in some cases, to liver cancer. Hepatitis C can also become chronic. HDV, common in the Mediterranean region, can only replicate in the presence of of HBV. HEV is endemic in some tropical countries. Vaccines are available against HAV and HBV.
Hepatitis A
Hepatitis A is a contagious, acute inflammatory disease of the liver. The CDC estimates that nearly 25,000 people contracted hepatitis A in the United States in 2007, although the number of reported cases is much lower because some people do not show symptoms. Most people who contract hepatitis A will recover completely, but an estimated 100 people die from the infection every year in the United States.
Cause
Hepatitis A is caused by the hepatitis A virus, which is found in the stool and blood of an infected person.
Transmission
People become infected with hepatitis A when they orally ingest the fecal matter – even just microscopic traces – of infected individuals. This usually happens in one of two ways:
Hepatitis A is common in certain areas of the world where there is poor sanitation. Several outbreaks in the United States and elsewhere have also been associated with injecting and non-injecting drug use.
Symptoms
Hepatitis A does not always cause obvious symptoms. Some people may experience mild symptoms lasting one to two weeks, while others will have more severe symptoms that can last for several months. Generally, the severity of the illness increases with age, which is why children infected with the hepatitis A virus usually do not exhibit any symptoms. Symptoms of hepatitis A include the following:
Symptoms can appear anywhere from two to six weeks after exposure. However, it's important to note that infected people are contagious up to two weeks before they show any symptoms at all.
Diagnosis
Health care providers review symptoms and can diagnose hepatitis A with a blood test, which will reveal the presence of antibodies to hepatitis A virus.
Treatment
There are no medicines for treating hepatitis A infection after a person acquires it. In milder cases, doctors usually prescribe rest, plenty of fluids, and a nutritious diet. While the body fights hepatitis A, a person should avoid any medications – over-the-counter or prescribed – that could damage the liver. Sufferers should also avoid alcohol during the recovery period, as alcohol may also cause damage to the liver.
Prevention
The best way to prevent hepatitis A is to be vaccinated. The vaccine has been available since the 1990s, and health experts recommend it for travelers going to Africa, Asia, Central and South America, or Eastern Europe. People with certain allergic conditions and pregnant women may be encouraged to avoid the vaccine.
For those who are not vaccinated, the best ways to prevent hepatitis A infection are practicing good sanitation and hygiene and avoiding contaminated food and water, especially when traveling in countries where hepatitis A is common.
Taking immunoglobulin (a protein that fights infection) will help keep people from getting sick when they have been exposed to the hepatitis A virus during an outbreak.
Hepatitis B
Hepatitis B is a contagious, acute disease of the liver that may become chronic. The CDC estimates that nearly 43,000 people contracted hepatitis B in the United States in 2007, although the number of reported cases is much lower because some people do not show symptoms. There are an estimated 800,000 to 1.4 million chronic cases in the United States. Globally, there are about 360 million chronically infected people, and as many as 626,000 people die of hepatitis B every year.
Cause
Hepatitis A is caused by the hepatitis A virus, which is found in the stool and blood of an infected person. Acute hepatitis B is caused by the hepatitis B virus, which is found in certain body fluids of infected persons. Chronic, or lifelong, hepatitis B is caused when the virus remains in the body beyond the acute stage.
Transmission
Hepatitis B virus can be found in the blood, semen, vaginal fluids, and other body fluids of infected people. Transmission happens when infected body fluids enter another person's body. The virus is most commonly transmitted in the following ways:
Hepatitis B is not transmitted through shaking hands, coughing, sneezing, breastfeeding, or sharing cups and utensils.
Symptoms
Hepatitis B does not always cause obvious symptoms. Children are less likely than adults to exhibit symptoms, but they are more likely than adults to develop chronic hepatitis B after an acute infection.
Symptoms of acute hepatitis B include the following:
Symptoms of acute hepatitis B generally appear three months after exposure to the virus and may last for a period of several weeks to six months.
People with chronic hepatitis B may exhibit no symptoms for two to three decades, but around 15 to 25 percent of those chronically infected may develop serious liver disease that is not initially apparent. Chronic infection can ultimately lead to long-term liver damage, liver cancer, or liver failure – all of which can be fatal.
Diagnosis
Health care providers review symptoms and can diagnose hepatitis B with a blood test or a combination of blood tests, which will reveal the presence of hepatitis B virus or antibodies to it.
Treatment
There are no medicines for treating acute hepatitis B infection after a person acquires it. In milder cases, doctors usually prescribe rest, plenty of fluids, and a nutritious diet. While the body fights hepatitis B, a person should avoid any medications – over-the-counter or prescribed – that could damage the liver. Sufferers should also avoid alcohol during the recovery period, as alcohol may also damage the liver.
Chronic hepatitis B can be treated with certain medications, but most people will not have complications severe enough to require medication. Those with active liver disease may be prescribed one of several approved medications for preventing liver damage. Those who show no signs of liver damage should be monitored by a doctor to ensure that liver disease, should it occur, is found early.
Prevention
The best way to prevent hepatitis B is to be vaccinated. The hepatitis B vaccine is usually administered in a series of three or four shots given over a six-month period. The vaccine is safe for adults and children and is routinely given to infants at birth.
Hepatitis C
Hepatitis C is an infectious disease of the liver. Worldwide, health experts estimate that 180 million people have chronic hepatitis C, with more than 4 million of those cases in the United States.
Hepatitis C, like all forms of hepatitis, can damage the liver. Of people infected, 55 to 85 percent will develop chronic infection, and 75 percent of those with chronic infection will develop chronic liver disease.
Cause
Hepatitis C is caused by infection with the hepatitis C virus. This virus causes chronic (long-term) infection in more than 85 percent of infected people, often leading to chronic liver disease. Hepatitis C is unrelated to any of the other known hepatitis viruses (A, B, D, and E).
Transmission
People can get hepatitis C from infected blood or body fluids. Today, the most common mode of transmission is needle-sharing during intravenous drug use, and most new infections now occur among intravenous drug users.
Since 1992, when reliable blood screening procedures became available, the risk of transmission of hepatitis C by blood transfusion has fallen to less than one per million units of transfused blood, according to the CDC.
Rarely, the virus can be transmitted through sexual intercourse. In addition, an infected pregnant woman can infect her unborn baby.
Hepatitis C is not transmitted through shaking hands, coughing, sneezing, breastfeeding, or sharing cups and utensils.
Symptoms
Most people with acute or chronic hepatitis C have few, if any, symptoms and are not even aware they are infected. If symptoms are present, they may include
Symptoms of acute hepatitis C, if they appear at all, generally appear 6 to 12 weeks after exposure to the virus.
Despite a lack of apparent symptoms, some people with chronic hepatitis C may develop serious liver disease that is not initially apparent. In the United States, chronic hepatitis C infection is the leading cause of cirrhosis (severe liver disease) and liver cancer, both of which can be fatal.
Diagnosis
Health care providers can diagnose hepatitis C with a blood test.
Those diagnosed with chronic hepatitis C may be advised to undergo a liver biopsy to diagnose chronic liver disease. Unfortunately, by the time a provider diagnoses serious liver disease, liver damage can be considerable and even irreversible. This damage often results in cirrhosis (end-stage liver disease) or liver cancer.
The symptoms of liver damage may not appear for several years. Therefore, it is important for people at high risk of infection to be tested for hepatitis C, so they can start treatment as early as possible. High-risk groups include the following:
Treatment
People diagnosed with hepatitis C infection will be examined for liver disease and prescribed medicine to eliminate the virus. Two medicines are used to treat hepatitis C: interferon and ribavirin. Most health experts advise using both drugs together. The response to treatment varies from individual to individual.
Around 15 to 25 percent of those infected with hepatitis C will recover completely.
Because other hepatitis viruses and alcohol use are associated with faster progression of the disease, health experts advise infected people to avoid drinking alcohol and to be vaccinated against hepatitis A and hepatitis B viruses.
Prevention
Currently, there is no vaccine to prevent hepatitis C infection, but people can take precautions to protect themselves against becoming infected with hepatitis C virus and to prevent passing on the virus to others. The CDC recommends these steps:
Hepatitis D
Hepatitis D is a viral infection that damages the liver, but it can propagate only when the hepatitis B virus is also present. Approximately 15 million people worldwide are infected with hepatitis D.
Cause
Hepatitis D is caused by the hepatitis D virus, which is found in certain body fluids of infected persons, but it remains in the body only if the hepatitis B virus is also present.
Transmission
Hepatitis D can be found in the blood, semen, vaginal fluids, and other body fluids of infected persons. Transmission happens when infected body fluid enters another person's body, but hepatitis D will not remain in the body unless hepatitis B is also present. The virus is most commonly transmitted in the same ways that hepatitis B is transmitted:
There are two types of hepatitis D infection:
Symptoms
Symptoms include the following:
Diagnosis
Health care providers review symptoms and can diagnose hepatitis D with a blood test, which will reveal the presence of antibodies to the hepatitis D virus.
Treatment
The acute form of the hepatitis D virus is more likely to disappear on its own in co-infection cases, when hepatitis B and hepatitis D are contracted simultaneously. Fewer than 5 percent of people co-infected will develop chronic hepatitis D.
In superinfection cases, in which a person with chronic hepatitis B subsequently contracts hepatitis D, up to 80 percent of people will develop chronic hepatitis D. These cases may result in severe chronic hepatitis D that often progresses to cirrhosis (end-stage liver disease) or cancer of the liver. The drug interferon may be helpful in treating disease conditions in some patients.
Prevention
Because hepatitis D requires the presence of hepatitis B to propagate, the best way to prevent hepatitis D infection is to be vaccinated against hepatitis B.
However, there is no vaccine to prevent those who already have developed chronic hepatitis B from contracting hepatitis D. The best course of action for hepatitis B carriers is to avoid the high-risk behaviors associated with hepatitis D superinfection, including
Hepatitis E
Hepatitis E is a contagious, acute inflammatory disease of the liver. It does not develop into a chronic disease.
Cause
Hepatitis E is caused by the hepatitis E virus, which is found in the stool of an infected person.
Transmission
PTransmission of the hepatitis E virus generally occurs when someone ingests water that is contaminated with the fecal matter – even just microscopic traces – of an infected person. Major outbreaks typically happen in regions of the world where sanitation is poor.
Few cases of hepatitis E have resulted from person-to-person contact, and there is no evidence that the virus can be spread through sexual activity. Transmission via blood is rare.
Symptoms
Not all people infected with hepatitis E will show symptoms, but three to eight weeks after infection, those who do have symptoms may experience the following:
Diagnosis
Health care providers review symptoms and can diagnose hepatitis E with a blood test, which will reveal the presence of antibodies to the hepatitis E virus. However, the test is not available in the United States.
Treatment
There are no medicines for treating a hepatitis E infection after a person acquires it. In milder cases, doctors usually prescribe rest, plenty of fluids, and a nutritious diet. While one's body fights hepatitis E, a person should avoid any medications – over-the-counter or prescribed – that could damage the liver. Sufferers should also avoid alcohol during the recovery period, as alcohol may also damage the liver.
Prevention
Currently, there is no approved vaccine for hepatitis E, though a promising candidate developed in part by NIAID has been successful in clinical trials.
The best way to prevent a hepatitis E infection is avoiding contaminated water, especially when traveling in countries where hepatitis E is common.
