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Los Angeles Hepatitis Organization |
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Home About LAHO Topics Reports Search Report Case Links Comments |
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Hepatitis A is a liver disease caused by the hepatitis A virus. Hepatitis A can affect anyone. In the United States, hepatitis A can occur in situations ranging from isolated cases of disease to widespread epidemics. Hepatitis A can affect anyone. In the United States, hepatitis A can occur in situations ranging from isolated cases of disease to widespread epidemics. Good personal hygiene and proper sanitation can help prevent hepatitis A. Vaccines are also available for long-term prevention of hepatitis A virus infection in persons 2 years of age and older. Immune globulin is available for short-term prevention of hepatitis A virus infection in all ages. Persons with hepatitis A virus infection may not have any signs or symptoms of the disease. Older persons are more likely to have symptoms than children. If symptoms are present, they usually occur abruptly and may include fever, tiredness, loss of appetite, nausea, abdominal discomfort, dark urine, and jaundice (yellowing of the skin and eyes). Symptoms usually last less than 2 months; a few persons are ill for as long as 6 months. The average incubation period for hepatitis A is 28 days (range: 15–50 days).
This is a serious disease caused by a virus that attacks the liver. The virus, which is called hepatitis B virus (HBV), can cause lifelong infection, cirrhosis (scarring) of the liver, liver cancer, liver failure, and death. Hepatitis B is a serious disease caused by the hepatitis B virus (HBV) which is present in the blood and body fluids of an infected individual. The virus can be transmitted from mother to baby at birth as well as through unprotected sexual intercourse, and un-sterilized needles. HBV infection can cause acute illness that leads to loss of appetite; tiredness; pain in muscles, joints, or stomach; diarrhea or vomiting; and yellow skin or eyes (jaundice). HBV can also cause chronic infection, especially in infants and children, that leads to liver damage (cirrhosis), liver cancer, and death. Each year in the United States, an estimated 200,000 people have new HBV infections, of whom more than 11,000 people are hospitalized and 20,000 remain chronically infected. Overall, an estimated 1.25 million people in the United States have chronic HBV infection, and 4,000 to 5,000 people die each year from hepatitis B related chronic liver disease or liver cancer (Centers for Disease Control and Prevention (CDC), 1990; Margolis, 1991; West, 1992).
You may have hepatitis B (and be spreading the disease) and not know it; sometimes a person with HBV infection has no symptoms at all.
If you have symptoms
your eyes or skin may turn yellow
you may lose your appetite
you may have nausea. vomiting, fever, stomach or joint pain
you may feel extremely tired and not be able to work for weeks or months
There is no cure for hepatitis B; this is why prevention is so important. Hepatitis B vaccine is the best protection against HBV. Three doses are needed for complete protection.
This is a liver disease caused by the Hepatitis C virus (HCV), which is found in the blood of persons who have the disease. HCV is spread by contact with the blood of an infected person. There are several blood tests that can be done to determine if you have been infected with HCV. PCR and other tests to directly detect virus are not licensed tests and are only available on a research-basis. A single positive PCR test indicates infection with HCV. A single negative test does not prove that a person is not infected. Virus may be present in the blood and just not found by PCR. Also, a person infected in the past who has recovered may have a negative test. When hepatitis C is suspected and PCR is negative, PCR should be repeated.
This is a defective virus that needs the hepatitis B virus to exist. Hepatitis D virus (HDV) is found in the blood of persons infected with the virus. HDV is a single-stranded RNA virus that requires the helper function of HBV to replicate. HDV requires HBV for synthesis of envelope protein composed of HBsAg, which is used to encapsulate the HDV genome. HDV infection can be acquired either as a co-infection with HBV or as a superinfection of persons with chronic HBV infection. Persons with HBV-HDV co-infection may have more severe acute disease and a higher risk of fulminant hepatitis (2%-20%) compared with those infected with HBV alone; however, chronic HBV infection appears to occur less frequently in persons with HBV-HDV co-infection. Chronic HBV carriers who acquire HDV superinfection usually develop chronic HDV infection. In long-term studies of chronic HBV carriers with HDV superinfection, 70%-80% have developed evidence of chronic liver diseases with cirrhosis compared with 15%-30% of patients with chronic HBV infection alone.
This type of hepatitis is a virus (HEV) transmitted in much the same way as hepatitis A virus. Hepatitis E, however, does not often occur in the United States. Hepatitis E virus (HEV), the major etiologic agent of enterically transmitted non-A, non-B hepatitis worldwide, is a spherical, non-enveloped, single stranded RNA virus that is approximately 32 to 34 nm in diameter. Based on similar physicochemical and biologic properties, HEV has been provisionally classified in the Caliciviridae family; however, the organization of the HEV genome is substantially different from that of other caliciviruses and HEV may eventually be classified in a separate family. The incubation period following exposure to HEV ranges from 15 to 60 days (mean, 40 days). Typical clinical signs and symptoms of acute hepatitis E are similar to those of other types of viral hepatitis and include abdominal pain anorexia, dark urine, fever, hepatomegaly, jaundice, malaise, nausea, and vomiting. Other less common symptoms include arthralgia, diarrhea, pruritus, and urticarial rash. The period of infectivity following acute infection has not been determined but virus excretion in stools has been demonstrated up to 14 days after illness onset. In most hepatitis E outbreaks, the highest rates of clinically evident disease have been in young to middle-age adults; lower disease rates in younger age groups may be the result of an icteric and/or subclinical HEV infection. No evidence of chronic infection has been detected in long-term follow-up of patients with hepatitis E.
Hepatitis G virus is clearly a transmissible agent that may be spread in the same manner as other conventional blood-borne viral agents. Hepatitis G virus (HGV) is prevalent in patients with chronic liver disease and has been previously detected in liver specimens. Diagnosis of HGV infection currently depends on the use of polymerase chain reaction (PCR) to detect viral RNA in serum or other infected fluids or tissues. Attempts to develop an antibody detection system suitable for diagnosis have thus far been unsuccessful. Although PCR is very sensitive, its exact sensitivity and specificity are not yet known. If anything, the use of PCR may underestimate the prevalence of HGV infection, particularly in persons who have recovered from that infection or are not currently viremic. (Hepatitis G Virus Infection: A Work in Progress, Annals of Internal Medicine, 1 November 1996. 125:772-773.
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All information presented in these pages is for Epidemiology 414 |
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Georgina E. Castle |
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UCLA, School of Public Health |