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HEPATITIS. Cheryl Ryan Renee Baker. Hepatitis is the inflammation of the liver caused by a virus . The disease targets liver cells, hepatocytes . There are currently eleven viruses recognized as causing hepatitis: 2 are herpesviruses
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HEPATITIS Cheryl Ryan Renee Baker
Hepatitis is the inflammation of the liver caused by a virus . • The disease targets liver cells, hepatocytes. • There are currently eleven viruses recognized as causing hepatitis: 2 are herpesviruses 9 are hepatotropic ( 5 are well characterized: A, B, C, D, and E)
Taxonomy • Hepatitis A Virus (HAV) - Picornaviridae, Hepatovirus • Hepatitis B Virus (HBV) - Orthohepadnavirus, Hepodnaviridae • Hepatitis C Virus (HCV) - Flaviviridae
Ecology of the Virus • Biological vectors – humans, contaminated food and water, contaminated needles • HAV- can live outside the body for months, depending on the environmental conditions. • HBV - can survive outside the body at least 7 days. • HCV- can survive outside the body and still transmit infection for 16 hours, but not longer than 4 days.
Infection Process- Hepatitis A • HAV enters the gut • replicates in the alimentary tract • spreads to infect the liver • multiplies in hepatocytes
Infection Process – Hepatitis B & C • The virus attaches to the liver cell and is transported inside. • Viral particles are released into the nucleus. • The virus is replicated and then released from the cell.
Symptoms • Jaundice • Fatigue • Abdominal pain • Loss of appetite • Nausea • Diarrhea • Fever • Joint Pain ( HBV) • Dark Urine (HCV)
Diagnostic Tests • Serological testing – presence of IgM antibody to HAV • Blood Tests (HBV and HCV)
Treatments • HAV – vaccine is the best prevention • HBV – vaccine • HCV – there is no vaccine available • Who should be vaccinated? • Who should not be vaccinated?
Prevention • Surest way to prevent transmission is to avoid sexual contact with infected persons. (HBV and HCV) • Never inject illegal drugs. • Do not share personal care items. • Consider the risks of getting tattoos and piercings. • Wash hands with soap and water after using the bathroom, changing a diaper, and before preparing and eating food. (HAV)
Epidemiology • HAV – Before the vaccine became available there were 35,000 cases per year. Number of new hepatitis A cases: 5,683 (2004) • Transmitted by fecal-oral contamination, sexual contact, illegal drug use, and consumption of contaminated food. • As little as 10-100 viral particles are needed to infect the host. • 1/3 have evidence of past infection. • Hepatitis E is similar to Hepatitis A.
Epidemiology (cont.) • HBV – Generally transmitted through body fluids and sexual contact, illegal drug use and needle sticks, and healthcare settings. • As of 1997 more than 80 countries had adopted routine HBV vaccinations for children. • The number of new infections per year declined from 260,000 in the 1980’s to about 60,000 in 2004. • Hepatitis D only occurs when the host is infected with HBV. • Estimated 1.25 million chronically infected Americans, of whom 20-30% acquire their infection in childhood.
Epidemiology (cont.) • HCV – Transmission occurs when contaminated blood enters the body of a person who is not infected. • Most infections are due to illegal injection drug use. • Estimated 4.1 million (1.6%) of Americans have been infected with HCV. • The number of new infections has declined from approximately 240,000 in the 1980’s to about 26,000 in 2004. • Transfusion associated cases now occur in less than 1 per 2 million transfused units of blood.
Morbidity and Mortality • HAV – There is no chronic infection. • About 15% of people infected will have prolonged or relapsing symptoms over a 6-9 month period. • HBV -Each year, approximately 600,000 deaths occur worldwide (2003). • Death from chronic liver disease occurs in 15-25% • HCV – 1-5% of infected persons die from chronic liver disease. • Leading cause for liver transplants.
Latest Research • Alpha Interferon which results in sustained remission in selected patients is the only available therapy for treatments of persons with chronic hepatitis C. • Prevention of HCV infection by vaccination is likely to be challenging if ongoing viral mutations continue.
References • www.cdc.gov • www.clinchem.org • http://www.nlm.nih.gov/medlineplus/hepatitisc.htm • www.webmd.com • http://digestive-disorders.health-cares.net/viral-hepatitis.php • http://web.uct.ac.za/depts/mmi/jmoodie/dihep.html • www.journals.asm.org • www3.niaid.nih.gov • Sherwood, LM, Willey J, Woolverton C. Microbiology. 200