Hepatitis A CMAJ 1997;156(4):545 © 1997 Canadian Medical Association Between 1000 and 3000 cases of hepatitis A are reported in Canada each year, but because the disease is frequently asymptomatic (especially in young children) the actual incidence is considerably higher.[1] Transmission is by the fecal­oral route, either directly through interpersonal contact or indirectly through ingestion of contaminated food or water. Clinical illness can arise 15­50 days after exposure and typically involves fever, malaise, appetite loss, nausea, abdominal pain and jaundice. Recovery is usually complete within 2 months, and infection confers lifelong immunity.[2] People at risk include residents of communities with high rates of infection, children and staff at day-care centres, staff and residents of long-term care facilities, blood product recipients, injection drug users and gay men. Travel to Africa, Asia, Southeast Asia, Central and South America, eastern and southern Europe, Greenland and the Middle East increases risk of exposure, even for tourists with standard itineraries.[2] Prevention Careful handwashing will prevent most household and institutional spread. Travellers should avoid consuming untreated water, iced drinks, uncooked shellfish, and uncooked fruit and vegetables they have not prepared themselves. It is wise to follow the maxim, "If you can't peel it or boil it, don't eat it." The virus is inactivated by heating to 85°C for 1 minute. Surfaces can be disinfected with household bleach.[2] Careful handwashing after sexual intercourse and after disposal of condoms, particularly after anal intercourse, will lessen the risk of infection. Vaccine Vaccination should be offered to patients at high risk (see Table 1 for dosages). It may be cost effective to screen for antibodies first. Seroconversion takes 4 weeks, and antibodies persist for at least 1 year. Booster doses, given at 6 months or later, confer long-term immunity.[3] Two products are available: HAVRIX (SmithKline Beecham Pharma) and VAQTA (Merck Frosst). Both are administered by injection in the deltoid muscle. HAVRIX has 2 formulations: HAVRIX 720 and HAVRIX 1440. HAVRIX 720 is no longer being manufactured and will become unavailable. VAQTA comes in adult and pediatric doses. The safety of hepatitis A vaccination during pregnancy and lactation has not been established.[3] Immune globulin Patients likely to be exposed to the virus less than 4 weeks after vaccination may be given immune globulin (IG) concurrently at a separate injection site. Children under 2 years and patients allergic to any vaccine component can be given IG. Close contacts of infected people should receive IG in a single dose within 2 weeks (preferably 72 hours) after exposure. Serologic testing before administration of IG is unnecessary and causes delay. IG is safe for use during pregnancy.[1] Dosage may vary among IG products; consult the product monograph. -- JH, AMT References Statement on the prevention of hepatitis A infections. Can Commun Dis Rep 1994;20:133-6, 139-43. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1996;45(no RR-15):1-30. Supplementary statement on hepatitis A prevention. Can Commun Dis Rep 1996;22:1-3. | CMAJ February 15, 1997 (vol 156, no 4) |