Suspected cases must be reported immediately by phone to the Thunder Bay District Health Unit at 625-8318 or toll-free 1-888-294-6630, ext. 8318 (Monday-Friday, 8:30am to 4:30pm). After hours and on weekends/holidays call Thunder Bay Answering Service at (807) 624-1280.
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 of infection. Infection is usually asymptomatic or inapparent in children, and jaundice develops in < 10% of children 6 years and under. Adults are typically symptomatic, with more severe disease. Symptoms may range from mild flu-like illness; to 1 to 2 weeks of mild, self-limited disease with jaundice; to fulminant hepatitis. Typically, acute clinical illness is characterized by a 1 to 7 day prodrome of abrupt onset fever, malaise, anorexia, nausea and abdominal pain followed by jaundice. Dark urine and light-coloured stools, as well as pruritis may occur, and an enlarged liver may be seen. Extra-hepatic complications may occur. It has been reported that between 3% and 20% of cases may experience relapsing disease. Fulminant hepatitis and death are rare. There is usually complete recovery without complications or sequelae. 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. seafood harvested from contaminated water). Fecal-oral transmission has been reported as the mode of transmission in outbreaks associated with daycare center employees or attendees.
In recent years, contaminated produce (such as green onions, blueberries, frozen strawberries, sun dried tomatoes, salad and lettuce) along with oysters and orange juice, have been associated with community-wide outbreaks (see additional resources).
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. For example, several outbreaks have been associated with injecting and non-injecting drug use and men with multiple male sex partners.
Transmission from mother to newborn infant (that is, vertical transmission) is rare.
The virus may persist for days or weeks in the environment.
The incubation period ranges from 15 to 50 days with an average of 28 to 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 & 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 & Case Management
Treatment is under the direction of the individual’s health care provider.
Provide education to patients regarding transmission and personal hygiene (hand hygiene after defecation, before and after sexual contact and before handling food).
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 'Publicly Funded Immunization Schedules for Ontario (December 2016)' for post-exposure prophylaxis recommendations with Hepatitis A vaccine and Hepatitis A Immune globulin.
- Ministry of Health and Long Term Care, Infectious Diseases Protocol, 2016. Appendix A (2017) and Appendix B (2017)
3. Heymann, D.L. Control of Communicable Disease Manual (20th Ed.). Washington, American Public Health Association, 2015.