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Viral Hepatitis |
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Hepatitis A ¨ Transmitted via the faeco-oral route ¨ 3-week incubation period. ¨ There is no known carrier state.
Hepatitis B ¨ May be transmitted by blood-to-blood contact e.g. via contaminated sharps, and droplet infection. ¨ It has an incubation period of 6 weeks to 6 months. ¨ A small proportion of patients will progress to a hepatitis B carrier state associated with chronic active hepatitis and eventually cirrhosis. ¨ The presence of Hepatitis B Surface Antigen (HBsAg) is the first manifestation of infection. ¨ The presence of antibody to HBs is associated with protection from infection. ¨ Hepatitis B Core Antigen (HBcAg) is detected by the development of an antibody to it. It may persist for 1 to 2 years signifying donor infectivity if HBsAg negative but HBcAg positive. ¨ Hepatitis B e Antigen is only found in HBsAg positive sera and appears during the incubation period. It is an index of infectivity. ¨ DNA polymerase is first detected when the level of HBsAg is increasing, and indicates the presence of virions in the serum and is associated with replication.
Hepatitis C Can be contracted from a contaminated blood transfusion.
Hepatitis D (or delta) Is a viral RNA associated with hepatitis B and demonstrated in association with HBcAg.
Other viral causes of a hepatitis include Cytomegalovirus, Herpes Simplex, Epstein Barr Virus and Coxsackie B Virus.
Efficient cross infection control should minimise the risk of contracting the infective types of hepatitis. There is an adjunct in the form of a hepatitis B vaccine (Engerix B). This vaccine is injected into the deltoid muscle of the upper arm and is repeated at 1 and 6 months after the original dose. Serology is used to time boosters and identify none or poor responders. Poor responders tend to be members of the older population, smokers and male.
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