Hepatitis A virus (HAV)
Hepatitis B virus (HBV)
This may follow blood transfusion, plasma infusion and, rarely, the administration of sera, infection resembling infective hepatitis except that the incubation period is about 12 weeks. Transmission by plasma has been reduced by avoiding the pooling of plasma from a large number of donors. Transmission by syringes is prevented if all syringes are disposable. It occurs amongst those who are drug addicts and possibly after tattooing or ear piercing. There is an extremely high rate among certain homosexual communities. In certain centres more than 50 per cent of male homosexual patients have antibody indicating exposure and about 5 per cent have active disease. In Athens, a group of prostitutes was found to have a rate 20 times that of married pregnant women, possibly due to more frequent coitus near the period or to other sexually transmitted diseases, producing bleeding that transmits the infection.
Infection with hepatitis B virus is associated with the appearance in the blood of one or more antigens, viz, hepatitis B surface antigen (HBsAg), hepatitis Be antigen (HBeAg), the Dane particle (probably the complete virus) and DNA polymerase activity. Under electron microscopy, particles can be seen in the sera of these patients and are associated with the virus. These particles are antigenic. Such patients usually suffer the severest form of hepatitis. The antigen is the scourge of renal dialysis and transplantation units, and hospital staff must avoid contact with blood from such patients.
A genetically engineered vaccine is now available (EngenixB). Three doses produce a good antibody response in most recipients, although poor responders may need a booster.
Good antibody levels usually persist for about 5 years and a booster is recommended at this time. It is important that the injection is given intramuscularly in the deltoid as this produces a higher response rate than the buttock. All surgeons are strenuously recommended to have a course of this vaccine.
Hepatitis nonA nonB is a variant, with an incubation period similar to HBV but with milder clinical features. Several causative agents have been described, one of which is hepatitis C. Detection of antibodies to hepatitis C indicates exposure to the disease and the presence of viral nibonucleic acid (RNA) in the blood indicates chronic infection. There is a number of serotypes with varying responses to therapy with a combination of interferon and ribavinin. Sadly, a large number of patients relapses after treatment and the development of new and more effective antiviral agents is awaited.
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