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| Hepatitis B |
Disease
Acute viral Hepatitis is a systemic infection affecting the liver predominately. Infection with Hepatitis B virus is one of the commonest cause leading to hepatitis. Hepatitis B virus (HBV) is usually transmitted by inoculation of infected blood or blood products or by sexual contact (heterosexual and/or homosexual) and is present in saliva, semen and vaginal secretions. Hepatitis B virus infected mothers may transmit HBV infection to the neonates at delivery, the risk of chronic infection in infant is as high as 90%. Groups at risk include patients and staff hemodialysis centres, physicians, dentists, nurses and personnel working at clinical and pathological labrotaries and blood banks. A person with chronic Hepatitis B infection particularly when HBV infection is acquired early in life, is at high substantial risk of cirrhosis and hepato-cellular carcinoma.
Occurrence
Hepatitis B infection is found worldwide. Its incidence is decreasing in countries where vaccination against Hepatitis B infection is being actively pursued and primitive measures to avoid transmission through sexual contact are being adhered to.
Risk for travellers
The risk depends on (1) the prevalence of HBV infection in the country of destination, (2) the extent of direct contact with blood or body fluids or of sexual contact with potentially infected persons, and (3) the duration and type of travel. The vaccine should be considered for virtually all non-immune individuals traveling to areas with moderate to high risk of infection.
Vaccine
Hepatitis B vaccine contains inactivated hepatitis B virus surface antigen (HBsAg) adsorbed on aluminum hydroxide adjuvant. It is made biosynthetically using recombinant DNA technology. And the two types are equally safe and effective. The vaccine is used in individuals at high risk of contracting hepatitis B, which are as follows:
- parenteral drug misusers, their sexual partners, and household contacts; other drug misusers who are likely to progress to injecting.
- Individuals who change sexual partners frequently.
- Close family contacts of a case or carrier
- Babies whose mother have had acute hepatitis B during pregnancy or are positive for hepatitis B surface antigen (regardless of e-antigen markers) hepatitis B vaccination is started immediately on delivery and hepatitis B immunoglobulin given at the same time (but preferably at a different site). Babies whose mothers are positive for hepatitis B surface antigen and for e-antigen antibody should receive the vaccine only (but babies weighing 1.5 kg or less should also receive the immunoglobulin regardless of the mother’s e-antigen antibody status.
- Individuals, those receiving regular blood transfusions or blood products, and carers responsible for the administration of such products.
- Patients with chronic renal failure including those on haemodialysis. Haemodialysis patients should be monitored for antibodies annually and re-immunised if necessary. Home carers (of dialysis patients) should be vaccinated.
- Individuals with chronic liver disease
- Healthcare personnel (including trainees) who have direct contact with blood or blood stained body fluids or with patients tissues;
- Laboratory staff who handle material that may contain the virus.
- Other occupational risk groups such as morticians and embalmers
- Staff and inmates of custodial institutions
- Those traveling to areas of high or intermediate prevalence who are at increased risk or who plan to remain there for lengthy periods.
- Families adopting children from countries with a high or intermediate prevalence of hepatitis B
- Foster carers and their families.
Immunisation may take up to 6 months to confer adequate protection and the duration of immunity is not known precisely, but a single booster 5 years after the primary course may be sufficient to maintain immunity for those who continue to be at risk.
Immunisation does not eliminate the need for commonsense precautions for avoiding the risk of infection from known carriers by the routes of infection which have been clearly established. Accidental inoculation of hepatitis B virus infected blood into a wound, incision, needle-prick or abrasion may lead to infection whereas it is unlikely that indirect exposure to a carrier will do so.
Specific hepatitis B immunoglobulin (HBIG) is available for use with the vaccine in those accidentally inoculated and in neonates at special risks of infection.
Three doses of vaccine constitute the complete series; the first two doses are usually given 1 month apart, with the third dose 1–12 months later. Immunization provides protection for at least 15 years and, according to current scientific evidence, probably for life. Because of the prolonged incubation period of hepatitis B, some protection will be afforded to most travellers following the second dose given before travel, provided that the final dose is given upon return.
A rapid schedule of administration of monovalent hepatitis B vaccine has been proposed by the manufacturer as follows: day 0; 1 month; 2 months. An additional dose is given 6-12 months after the first dose. A very rapid schedule of administration of monovalent hepatitis B vaccine has been proposed as follows: day 0; 7 days; 21 days. An additional dose is given at 12 months.
A combination vaccine that provides protection against both hepatitis A and hepatitis B may be considered for travellers potentially exposed to both organisms. This inactivated vaccine is administered as follows: day 0; 1 month; 6 months. A rapid schedule at day 0, 1 month and 2 months, with an additional dose at 12 months, has been proposed by the vaccine manufacturer, as well as a very rapid schedule with administration at day 0, day 7 and day 21 with a booster dose at 12 months.
Vaccination of persons who have doubtful history of immunization or adult population that have expected high rates of previous HBV infection, pre vaccination testing might reduce the cost by avoiding vaccination of persons who are already immune. |
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