Hepatitis A

Notification requirement for hepatitis A

Hepatitis A is an ‘urgent’ notifiable condition and must be notified by medical practitioners and pathology services immediately by telephone upon initial diagnosis (presumptive or confirmed). Pathology services must follow up with written notification within 5 days.

This is a Victorian statutory requirement.

Exclusion for hepatitis A

Exclude from childcare, school or work (for food handlers, and healthcare workers with direct patient contact) for 1 week after the onset of illness or jaundice and until they are well.

Infectious agent of hepatitis A

Hepatitis A virus (HAV), a hepatovirus from the Picornaviridae family, is the causative agent, primarily through the faecal–oral route.

Identification of hepatitis A

Clinical features

Hepatitis means inflammation of the liver. Hepatitis A causes acute viral hepatitis and does not lead to chronic hepatitis.

In children less than 6 years of age, 70 per cent of infections are asymptomatic. If illness does occur, it is typically not accompanied by jaundice (yellowing of skin or eyes).

Illness due to hepatitis A typically causes fever, fatigue, malaise, anorexia, loss of appetite, nausea, vomiting, abdominal pain, clay-coloured bowel movements, joint pain, and jaundice in more than 70 per cent of patients.

Dark urine usually precedes the development of jaundice, and mild pruritus (itching) may occur.

The disease can vary from a mild illness lasting 1–2 weeks to a severely disabling disease lasting several months.

Symptoms usually last less than 2 months, although 15 per cent of symptomatic people have prolonged or relapsed disease for up to 1 year.

Convalescence is often prolonged.

Rarely, fulminating hepatitis may occur, especially when hepatitis A infection complicates pre-existing liver disease.

The overall mortality rate from hepatitis A is 0.3–1.8 per cent in people aged over 50 years.

Diagnosis

The virus can be detected in the blood and stool of most people during the acute phase of infection.

A blood test indicating IgM anti-HAV antibodies in acutely ill or recently ill patients establishes the diagnosis. IgM anti-HAV antibodies become detectable 5–10 days after exposure. These antibodies are present for 2–4 months after infection and, rarely, can persist for more than 1 year.

False positive IgM results can also occur, especially in older people, so testing for anti-HAV IgM should ideally be done only when hepatitis A is clinically suspected.

A fourfold or greater increase in specific antibodies in paired sera detected by enzyme-linked immunosorbent assay (ELISA) also establishes the diagnosis.

IgG anti-HAV antibodies alone are evidence of past infection or immunisation.

In the acute stage of the illness, blood biochemistry shows elevated transaminase levels, indicating hepatocellular damage. The pattern of liver function tests may be nonspecific in later illness.

Rarely, people may have a relapse of acute hepatitis, with a second peak in aminotransferase elevation, or a cholestatic form of hepatitis A with prolonged pruritus.

Incubation period of hepatitis A virus

The incubation period is 15–50 days, with an average of 28–30 days.

Public health significance and occurrence of hepatitis A

Hepatitis A occurs worldwide. The incidence of disease is related to hygiene and sanitation conditions. When environmental sanitation is poor, infection is common and occurs at a young age. In some South-East Asian countries, more than 90 per cent of the general population can have serological evidence of prior infection with hepatitis A, compared with industrialised countries, with a rate of 33 per cent. In about half of all Victorian cases, no source is identified.

In industrialised countries, disease transmission is frequently among household and sexual contacts of an acute case. Sporadic cases occur in childcare centres with children in nappies, travellers to countries where the disease is endemic, people who inject drugs, and men who have sex with men.

Although a vaccination program for Indigenous children commenced in Queensland in 1999, Indigenous children remain at greater risk than non-Indigenous children, particularly for hospitalisation with hepatitis A.

Since 2010, there has been an average of approximately 20 notified cases per year in Victoria.

Common-source outbreaks, due to food contaminated by an HAV–infected food handler or food (shellfish, raw products) contaminated before entering the food chain, are rare.

Recent outbreaks have been associated with contaminated shellfish, lettuce, strawberries, river water and blueberries. In 1997, a large outbreak of hepatitis A was associated with consumption of raw oysters in New South Wales. In 2009, an outbreak was related to consumption of semidried tomatoes.

Outbreaks have been reported in susceptible people working with nonhuman primates raised in the wild.

Reservoir of hepatitis A virus

Humans and, rarely, nonhuman primates (chimpanzees and other primates) are reservoirs.

Mode of transmission of hepatitis A virus

Transmission is from person to person, predominantly via the faecal–oral route. Worldwide, most infection results from exposure to contaminated food or water.

Several outbreaks have been associated with injecting and noninjecting drug use. Rarely, transmission through blood and clotting factor concentrates from viraemic donors during their incubation period has been reported.

Period of communicability of hepatitis A

Cases are most infectious from the latter half of the incubation period until a few days after the onset of jaundice, and infectivity diminishes rapidly after liver dysfunction or symptoms appear.

Most cases are not infectious after the first week of jaundice.

Long-term carriage or excretion (up to 6 months) of the virus in faeces has been documented in infants and children.

Susceptibility and resistance to hepatitis A

All nonimmune people are susceptible to infection. Immunity after infection is usually lifelong.

Control measures for hepatitis A

Preventive measures

Education about good hygiene is important, particularly handwashing before handling food and eating, and after using the toilet. Inadequate sanitation and housing may contribute to endemic illness.

Provide proper water treatment and distribution systems, and sewage disposal.

Inactivated hepatitis A vaccines are available for use in people 1 year of age and over. Protection begins within 14–21 days after the first dose. A second dose is required for long-term protection, and seroconversion occurs after 4 weeks.

In Australia, the vaccine is recommended for:

• all travellers to, and all expatriates living in, moderate to high endemic areas (including all developing countries)
• Aboriginal and Torres Strait Islander children residing in the Northern Territory, Queensland, South Australia and Western Australia
• those whose occupation may put them at risk of acquiring hepatitis A
• those who live and work in rural and remote Indigenous communities
• childcare and preschool personnel
• carers of people with intellectual disabilities
• healthcare workers who regularly provide care for Aboriginal and Torres Strait Islander children
• plumbers or sewerage workers
• sex workers
• those whose lifestyle may put them at risk of acquiring hepatitis A
• men who have sex with men
• people who inject drugs
• people with intellectual disabilities
• people chronically infected with hepatitis B or hepatitis C viruses
• people with chronic liver disease.

Control of case

Treatment is generally supportive.

Educate the patient and their family on the need for strict hygiene practices, including hand hygiene.

Infected people should not prepare meals for others while infectious, nor share utensils, toothbrushes, towels or face washers.

Dispose of, or thoroughly wash, nappies of infants who have hepatitis A.

Control of contacts

Normal human immunoglobulin (NHIG) or, more commonly, monovalent inactivated hepatitis A vaccine can be used to prevent secondary cases in close contacts of hepatitis A cases, including:

• household and sexual contacts of the case
• staff and children in close contact with a case in a childcare centre
• people who have consumed food prepared by a case.

Post-exposure prophylaxis should be given within 2 weeks of exposure.

A close contact is a person who has had contact with a case during the 2 weeks before and up until 1 week after the onset of jaundice or dark urine.

Prophylaxis is rarely given to people exposed to a potential common source of hepatitis A, such as food or water, because cases related to such a source are usually recognised too long after the exposure for it to be effective.

The department will determine the need for recall and/or prophylaxis of customers of an establishment, or mass interventions at a childcare facility.

Surveillance of contacts in a household or workplace should be maintained.

Live vaccines such as measles–mumps–rubella (MMR) should not be administered for 3 months after a dose of NHIG, and may also be ineffective if given in the 14 days before NHIG. Reschedule such routine vaccinations.

Control of environment

A source of infection should always be sought. For apparently sporadic cases, consider contact with another known case and recent travel to an area where the disease is endemic. Acquisition of infection from young children, particularly those in childcare, should be considered.

Special attention should be given to toilet hygiene in schools and childcare centres. Ensure that soap and water are available, and are used regularly to wash hands.

Outbreak measures for hepatitis A

Outbreaks can evolve slowly, cover wide geographical areas and last months, whereas common-source outbreaks may evolve rapidly.

Clusters of cases possibly related to a single source will require epidemiological and environmental investigation, including case finding and surveillance, and public health measures to prevent further cases.

Use of the hepatitis A vaccine in an outbreak setting is dependent on rapid identification of the outbreak and people at risk, and the ability to achieve high vaccine coverage levels.