Severe Acute Respiratory Syndrome (SARS)

Causative agent

Severe acute respiratory syndrome (SARS) is a viral respiratory infection caused by SARS-associated coronavirus (SARS-CoV). Since 2004, there have not been any SARS cases reported in the world.

Clinical features

The initial symptoms are similar to influenza infection. Patients with SARS usually begin with high fever (38°C or above), sometimes associated with chills, rigors, headache, malaise, muscle pain or even diarrhoea. At the onset of illness, some patients may only have mild respiratory symptoms. After a few days, symptoms of lower respiratory tract infection may follow, including cough and difficulty in breathing. In around 10%-20% of patients, the illness may rapidly progress to respiratory failure requiring intensive medical care. Symptoms can be more variable among elderly patients.

Mode of transmission

SARS is predominantly transmitted through close person-to-person contact, via respiratory droplets produced when an infected person coughs or sneezes. Droplet spread can take place when droplets from the cough or sneeze of an infected person are propelled a short distance and deposited on the mucous membranes of the mouth, nose, or eyes of persons who are nearby. The virus can also spread indirectly when a person touches a surface or object contaminated with infectious droplets and then touches his or her mouth, nose, or eyes.

Incubation period

Symptoms usually appear within 2 to 7 days after contracting the disease, but the incubation period can be up to approximately 10 days.

Management

There is currently no specific treatment for the disease. Treatment is mainly supportive.

Prevention

There is no vaccine currently available. Maintain good personal and environmental hygiene remains the most effective way to minimise the risk of contracting and spreading the disease.

1. Maintain good personal hygiene

• The wearing of mask is advised for the following situations - 
• any persons with fever or respiratory symptoms;
• any persons who are visiting or working in high-risk places such as residential care homes for the elderly, residential care homes for persons with disabilities, and clinical areas of healthcare facilities; and
• high-risk persons (e.g. persons with underlying medical conditions or persons who are immunocompromised) who are going to crowded places such as on public transport.
• When an increasing trend in activity of respiratory viruses is expected, high-risk persons are recommended to wear a surgical mask when visiting public places, while the public should also wear a surgical mask when taking public transportations or staying at crowded places.
• It is important to wear a mask properly, including to perform hand hygiene before wearing and after removing a mask. For details on proper mask wearing, please visit CHP website at www.chp.gov.hk/files/pdf/use_mask_properly.pdf;
• Perform hand hygiene frequently, especially before touching the mouth, nose or eyes; after touching public installations such as handrails or door knobs; or when hands are contaminated by respiratory secretion after coughing or sneezing.
• 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, perform hand hygiene with 70 to 80% alcohol-based handrub is an effective alternative.
• Cover your mouth and nose with tissue paper when sneezing or coughing. Dispose of soiled tissues into a lidded rubbish bin, then wash hands thoroughly.
• When having respiratory symptoms, wear a surgical mask, refrain from work or attending class at school, avoid going to crowded places and seek medical advice promptly.
• Build up good body immunity by maintaining a balanced diet, regular exercise and adequate rest, reducing stress, not smoking and avoiding alcohol consumption. 

2. Maintain good environmental hygiene

• 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.
• Maintain good indoor ventilation.
• Keep windows open to maintain good indoor ventilation;
• Wash dust filters of air-conditioners frequently;
• Maintain proper function of the air ventilation.
• Avoid going to crowded or poorly ventilated public places; high-risk individuals may consider putting on surgical masks while in such places.
• Maintain proper function of toilets, drains and pipes. U-trap should be prevented from drying up and drain outlets should be disinfected regularly (about once a week).
• Arrange immediate inspection and repair by qualified technicians if there is a defect in the U-trap or smell of foul air is coming from drain outlets.