Individuals who may or may not have hepatitis A shall be reported to the local Health Unit.
Hepatitis A infection is caused by the Hepatitis A virus (HAV), a 27-nanometer picornavirus, positive-strand RNA virus. It has been classified as a member of the family Picornaviridae.
Typically, hepatitis A is an acute, self-limiting liver infection. Clinical presentation varies with age at time of infection. Infection among children less than six years of age is usually asymptomatic or mild without jaundice. Illness in older children and adults is typically characterized by a 1 to 7 day prodrome of abrupt onset of fever, malaise, loss of appetite, dark urine, nausea, and abdominal pain followed by jaundice. There is usually complete recovery without complications. Older persons and individuals with chronic liver disease and immunocompromising conditions can have an increased risk of progressing to fulminant hepatic failure resulting in death. Illness usually lasts less than two months; prolonged, relapsing hepatitis for up to one year occurs in 15% of cases; chronic infection is not known to occur.
Modes of Transmission
HAV infection is transmitted primarily by the fecal-oral route, through direct contact with infected people or indirectly through ingestion of contaminated water or foods (e.g. fresh and frozen produce, seafood harvested from contaminated water).
On rare occasions, transmission has been reported after exposure to HAV-contaminated blood or blood products obtained from viremic donors during the incubation period of their infection. Transmission may also occur through sexual activities that include direct or indirect oral-anal contact but not through exposure to saliva, semen or urine.
In addition to foodborne outbreaks, outbreaks have been associated with injecting and non-injecting drug use, men who have sex with men and child care setting employees or attendees.
The virus may remain infectious in the environment for several weeks.
The incubation period ranges from 15–50 days with an average of 28–30 days.
Period of Communicability
Maximum communicability occurs during the latter part of the incubation period with peak levels in the 2 weeks before clinical illness. Infectiousness diminishes rapidly thereafter and ends shortly after the onset of jaundice. Cases are considered non-infectious 7 days after onset of jaundice although prolonged viral excretion up to 6 months has been documented in infants and children. Chronic shedding of HAV in feces does not occur.
Immunity following natural infection is thought to be lifelong. Protective antibody levels following vaccination will persist for at least 20 years or longer and protection likely persists even when antibodies are no longer measurable due to immune memory. Immunization with hepatitis A vaccine will prevent infection. See the “Canadian Immunization Guide, evergreen edition, Part 4” for a list of high risk groups who are recommended to receive this vaccine.
Diagnosis and Laboratory Testing
Serology tests indicating IgM anti-HAV antibodies confirms recent infection. Antibodies are generally detectable in serum 5–10 days after infection and usually decrease to undetectable levels within 6 months after onset of infection. In rare cases, they may persist for longer.
Treatment and Case Management
Treatment is under the direction of the individual’s health care provider.
Provide education to cases regarding transmission and personal hygiene. Emphasis should be placed on proper hand hygiene practices (e.g. after using the bathroom). Encourage limiting food handling activities by the case and discourage the sharing of food prepared by the case for the duration of the infectious period.
Exclude cases such as food handler, child care staff and attendees and health care workers from high risk settings for 14 days after onset of symptoms, or 7 days after onset of jaundice, whichever comes earlier.
Public health staff will identify and assess contacts of cases (those living in the same household, sexual partners, drug sharing partners, contacts who are food handlers, daycare and institutional attendees or employees).
See the “Canadian Immunization Guide, evergreen edition, Part 4” for post-exposure prophylaxis recommendations with Hepatitis A vaccine and Hepatitis A Immune globulin as well as the PHO additional resource below.
Heymann, D.L. Control of Communicable Disease Manual (19th Ed.). Washington, American Public Health Association, 2008.