Infectious Period

In document Blue Book (Page 77-81)

• As long as there is fluid in the blisters.

• The faeces can remain infectious for several weeks.

Tre a t m e n t

• Usually none is required.

• Use paracetamol for fever and any discomfort. Do not use aspirin where there is fever.

• The disease itself is not serious. If the child complains of severe headache and fever persists, consult your local doctor immediately.

• Exclusion from school and child care centres is not usually recommended because the virus may be present in the faeces for many weeks.

Note

This disease is not to be confused with foot and mouth disease in cattle.

Hepatitis A

Victorian Statutory Re q u i re m e n t

Group B notification.

School and child care exclusion (see below).

Infectious Agent

Hepatitis A virus (HAV) (RNA picornavirus).

Clinical Features

Illness due to hepatitis A typically causes acute fever, malaise, anorexia, nausea and abdominal discomfort, followed a few days later by dark urine and jaundice.

Symptoms usually last several weeks, although convales-cence may sometimes be prolonged.

Severe illness may rarely occur when hepatitis A compli-cates pre-existing liver disease.

Infants and young children infected with hepatitis A may have few or no recognised symptoms, and are often anicteric (without jaundice).

Public Health Significance

Hepatitis A occurs worldwide.

In developing countries, most people are infected during childhood. In the developed world, with good sanitation and hygiene, most people now reach adulthood without experiencing infection. They are, therefore, at risk of infection from sporadic low-level transmission that occurs in the community. A large outbreak affecting homosexual men occurred in Australia and overseas during the early 1990s.

Common source outbreaks due to contaminated food are rare.

Method of Diagnosis

A blood test showing IgM anti-HAV antibodies confirms recent infection. These antibodies are present for two to four months after infection. IgG antibodies alone are evidence of past infection.

Blood biochemical testing shows elevated transaminase levels during the acute phase of hepatitis. Later in the illness, the pattern of liver function tests may be non-specific.

Adults usually experience a distinct illness with acute onset of symptoms and jaundice, but a high index of suspicion is needed to diagnose young children with few symptoms. Related adult cases are a clue.

R e se rvo i r

Humans.

Mode of Transmission

The highly infectious hepatitis A virus is spread by the faecal-oral route from person to person directly or via fomites (contaminated objects). It may also be spread via food or water.

Non-cooked foods, such as salads, may be contami-nated by infectious food handlers, and filter-feeding shellfish raised in contaminated waters may harbour the virus.

The precise timing and mode of transmission are often difficult to define.

Incubation Period

Usually 15 to 50 days; the average 28 to 30 days.

Period of Communicability

Cases are most infectious from the latter half of the incubation period until a few days after the onset of jaundice (corresponding to a peak in transaminase levels in anicteric cases).

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

Long-term carriage or excretion does not occur.

Susceptibility and Resistance

Most persons born in Australia after 1945 are suscepti-ble. Immunity after infection is probably lifelong.

Control of Case

• Determine the occupation of the case.

• Exclude the case from child care, school or work for one week after the onset of illness or jaundice.

• Educate the case and family on the need for strict hygiene practices.

• Do not prepare family meals while infectious, nor share eating utensils, toothbrushes, towels and face washers.

• Dispose of or thoughly wash nappies of infants with hepatitis A.

Control of Contacts

Normal immunoglobulin (IG), 0.02 ml/kg body weight, intramuscularly, is recommended for:

• Household and sexual contacts of the case.

• Staff and children in close contact with a case in a child care centre.

IG is not recommended for usual office, school or factory contacts.

IG is rarely given to persons 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 IG to be effective for the co-exposed persons.

Timely administration of IG will prevent or modify clinical illness for approximately six weeks after the dose.

However, people exposed and infected before the administration of IG may still experience a mild infection, and may have the potential to infect others if their per-sonal hygiene is not exemplary.

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

Live vaccines (for example, Mumps-Measles-Rubella) should not be administered for three months after a dose of IG, and may also be ineffective if given in the 14 days prior to IG. Reschedule such routine vaccinations.

When the case is a food handler:

• Consider serological testing of co-workers to determine whether they have been infected or are susceptible.

• Place uninfected susceptible co-workers under surveil-lance and give them immunoglobulin prophylaxis.

These persons remain at a risk of developing mild illness (modified by immunoglobulin) but can generally continue to work provided their personal hygiene and food handling practices are exemplary.

• Undertake surveillance for hepatitis A in patrons by seeking a history of exposure to the food premises from cases notified over the next two to three months.

• Carefully consider the role of the infected food handler.

If transmission to patrons appears likely, consider urgent follow-up of exposed patrons to offer them immunoglobulin prophylaxis. Note that when the index

Control of Environment

A source of infection should always be sought. For apparently sporadic cases, consider contact with an-other known case and recent travel to an area where the disease is endemic. If these do not provide an answer, acquisition from young children, particularly those in child care, should be considered.

A number of cases occurring at the one time should prompt a search for a common source, particularly food or water.

Special attention should be given to toilet hygiene in schools and child care centres. Ensure soap and water are available and are used.

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

Preventive Measures

Good hygiene is very important, particularly hand washing before eating or handling food and after using the toilet.

Inadequate sanitation and housing may contribute to endemic illness.

Use IG for contacts.

In document Blue Book (Page 77-81)

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