Hepatitis A

Causative agent

Hepatitis A is a liver disease caused by the hepatitis A virus (HAV).

Clinical features

Clinical features of hepatitis A are similar to those of other types of viral hepatitis. Typical signs and symptoms of hepatitis A include:

• Fever;
• Malaise;
• Loss of appetite;
• Diarrhoea;
• Nausea;
• Abdominal discomfort; and
• Jaundice (yellowing discolouration of the skin and sclera of the eyes, dark urine and pale stool).

Not everyone who is infected will have all of the symptoms. Adults have signs and symptoms of illness more often than children, and the severity of disease increases in older age groups. Recovery from symptoms following infection may be slow and may take several weeks or months.

Hepatitis A infection does not cause chronic liver disease and is rarely fatal, but it can cause debilitating symptoms and fulminant hepatitis (acute liver failure), which is associated with high fatality rates.

Mode of transmission

HAV is transmitted primarily by the faecal-oral route, that is, when an uninfected person contacts or ingests objects, food or water that has been contaminated with the faeces of an infected person. The virus can also be transmitted through close physical contact with an infectious person including sexual contact and not limited to anal-oral contact. Hepatitis A outbreaks among men who have sex with men have been reported. Waterborne outbreaks, though infrequent, are usually associated with sewage-contaminated or inadequately treated water.

Incubation period

The incubation period of hepatitis A is usually 14 – 28 days and can be up to 50 days.

Management

There is no specific treatment for hepatitis A. Therapy is aimed at maintaining comfort and adequate nutritional balance, including replacement of fluids that are lost from vomiting and diarrhoea.

Prevention

At the population level, the spread of hepatitis A can be reduced by:

• Adequate supplies of safe drinking water;
• Food safety practice; and
• Proper disposal of sewage within communities.

Improved sanitation, food safety and immunisation are effective ways to combat hepatitis A.

1.Maintain good personal hygiene

• Perform hand hygiene frequently, especially before eating or handling food, and after using the toilet or handling vomitus or faecal matter. Wash hands with liquid soap and water, and rub for at least 20 seconds. Then rinse with water and dry with a disposable paper towel or hand dryer. If hand washing facilities are not available, or when hands are not visibly soiled, hand hygiene with 70 to 80% alcohol-based handrub is an effective alternative.
• Wear gloves and a mask while disposing of or handling vomitus and faeces, and wash hands thoroughly afterwards.
• Use serving chopsticks and spoons at meal time. Do not share food and drinks with others.
• Refrain from work or school, and seek medical advice when suffering from vomiting or diarrhoea.
• Exclude infected persons and asymptomatic carriers from handling food and from providing care to children, elderly and immunocompromised people.

2. Maintain good environmental hygiene

• Keep the premises and kitchen utensils clean.
• As household detergent may not be able to kill HAV, regularly clean and disinfect frequently touched surfaces such as furniture, toys and commonly shared items with 1:99 diluted household bleach (mixing 1 part of 5.25% bleach with 99 parts of water), leave for 15 – 30 minutes, and then rinse with water and keep dry. For metallic surface, disinfect with 70% alcohol.
• Use absorbent disposable towels to wipe away obvious contaminants such as respiratory secretions, and then disinfect the surface and neighbouring areas with 1:49 diluted household bleach (mixing 1 part of 5.25% bleach with 49 parts of water), leave for 15 – 30 minutes and then rinse with water and keep dry. For metallic surface, disinfect with 70% alcohol.

3.Maintain good food hygiene

• Adopt the 5 Keys to Food Safety in handling food, i.e. Choose (Choose safe raw materials); Clean (Keep hands and utensils clean); Separate (Separate raw and cooked food); Cook (Cook thoroughly); and Safe Temperature (Keep food at safe temperature) to prevent foodborne diseases.
• Drink only boiled water from the mains or bottled drinks from reliable sources.
• Avoid drinks with ice of unknown origin.
• Purchase fresh food from hygienic and reliable sources. Do not patronize illegal hawkers.
• Eat only thoroughly cooked food.
• Clean and wash food thoroughly. Scrub and rinse shellfish in clean water. Remove the viscera if appropriate. All shellfish should be thoroughly cooked before eating.
• Heating to an internal temperature of 90°C for 90 seconds is required for cooking of molluscan shellfish. If possible, remove the shells before cooking as they impede heat penetration. Otherwise, boil at 100°C until their shells open; boil for additional three to five minutes afterwards. Discard any shellfish that do not open during cooking.
• When having hotpot, use separate chopsticks and utensils for handling raw and cooked food to prevent cross-contamination.

*Please visit the website of Centre for Food Safety for more information on food safety

4. Hepatitis A vaccination

Hepatitis A vaccination is a safe and effective means to prevent the infection. Persons who are at increased risk for acquiring hepatitis A and persons with increased risk for severe adverse consequences should discuss with their doctors about hepatitis A vaccination for personal protection. According to the Scientific Committee on Vaccine Preventable Diseases, Centre for Health Protection, the following groups are recommended to have hepatitis A vaccination:

• Travellers to endemic areas of hepatitis A
• Persons with clotting factors disorders receiving plasma-derived replacement clotting factors
• Persons with chronic liver diseases
• Men who have sex with men
  
  

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