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- Key messages
- Notification requirement for severe acute respiratory syndrome (SARS)
- Infectious agent for severe acute respiratory syndrome (SARS)
- Identification of severe acute respiratory syndrome (SARS)
- Incubation period of SARS coronavirus
- Public health significance and occurrence of severe acute respiratory syndrome (SARS)
- Reservoir of SARS coronavirus
- Mode of transmission of SARS coronavirus
- Period of communicability of severe acute respiratory syndrome (SARS)
- Control measures for severe acute respiratory syndrome (SARS)
- Severe acute respiratory syndrome (SARS) is an ‘urgent’ notifiable condition that must be notified immediately to the department by medical practitioners and pathology services.
- The world experienced the first SARS epidemic in 2003.
- It is unlikely, but not impossible, that another outbreak will be first detected in Australia.
- Health authorities are vigilant in SARS surveillance, so that any other outbreaks would quickly be detected.
- Older people are more prone to severe disease.
Notification requirement for severe acute respiratory syndrome (SARS)
Severe acute respiratory syndrome (SARS) 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.
Infectious agent for severe acute respiratory syndrome (SARS)
The infectious agent is SARS coronavirus (SARS CoV).
Identification of severe acute respiratory syndrome (SARS)
SARS is a severe lower respiratory tract infection, recognised in a 2003 epidemic. In the first week of illness, the patient develops influenza-like symptoms, which include fever, malaise, myalgia, headache and rigors. No individual symptom or cluster of symptoms has proven specific; however, a history of fever is the one most frequently reported.
The patient progresses to develop a cough (initially dry), dyspnoea and often diarrhoea (large volume and watery), usually in the second week of illness, although these features may occur earlier.
Severe cases progress to a rapidly increasing respiratory distress and hypoxia, with approximately 20 per cent of recognised cases requiring intensive care.
Upper respiratory symptoms such as rhinorrhoea and sore throat may occur but are uncommon.
Diagnosis and case definition
Any specific testing for SARS should only be performed after consultation with the Communicable Diseases Section of the department. When the department is consulted, the status of any outbreak can be ascertained, the exposure and epidemiological links can be clarified, the case may be notified, appropriate infection control processes can be confirmed, and suitable patient transfer can be arranged.
The testing algorithm for SARS is heavily dependent on the existence of human cases worldwide and locally. Investigation of a possible SARS-infected patient will include concurrent testing for other more common and likely respiratory pathogens through normal means (sputum, blood, nasal swabs, urine), as well as specific tests to detect SARS CoV.
The samples to be collected for SARS CoV specifically include:
- a left and right nasal swab, and a posterior pharyngeal wall swab, all placed into the same viral transport medium. These can have polymerase chain reaction (PCR) testing for many different respiratory viruses (respiratory multiplex), as well as for SARS CoV, if appropriate. An alternative is a nasopharyngeal aspirate
- stool samples, if diarrhoea is present
- serum for antibody titres and, where appropriate, convalescent serum for parallel testing.
Testing is only performed at the Victorian Infectious Diseases Reference Laboratory (VIDRL). All tests should be clearly labelled ‘For urgent SARS testing at VIDRL’.
Maintaining vigilance and SARS alert clusters
If SARS does re-emerge, it is unlikely, but not impossible, that the first place it is recognised will be Australia. The most likely scenario is that this will occur in another country or countries (particularly southern China, the source of the original outbreak), providing time for Australia to institute targeted surveillance and investigation of illness in travellers from defined outbreak areas, as was undertaken in the initial outbreak period.
Although both the World Health Organization (WHO) and Australian health authorities regard Australia as a low-likelihood country to first recognise a new SARS outbreak, a cautious approach is being taken. Maintaining vigilance for SARS is a surveillance protocol that seeks to ensure that Australian health authorities will detect any new SARS outbreak by the detection of ‘alert’ clusters of cases. These are clusters of apparent hospital-acquired cases in staff, patients and visitors to the same healthcare facility, which meet the WHO post-outbreak clinical case definition for SARS.
Incubation period of SARS coronavirus
The mean incubation period is 5 days, with a range of 2–10 days, although there are infrequent isolated reports of longer incubation periods.
Public health significance and occurrence of severe acute respiratory syndrome (SARS)
SARS came to the world’s attention in early 2003 when WHO declared a global public health alert in response to a severe respiratory illness due to an unidentified communicable pathogen.
The pathogen emerged out of southern China, creating a local outbreak of atypical pneumonia. Subsequent infection of international travellers resulted in the importation of possible SARS cases to 29 other countries around the world. Hong Kong, Hanoi, Singapore and Toronto received such infected travellers early in the outbreak, and further transmission within these cities resulted in local outbreaks, affecting many hundreds of people.
The overall case-fatality rate was approximately 10 per cent and was highest (> 50 per cent) in those over 60 years of age. A characteristic feature of the SARS outbreak was its unprecedented degree of nosocomial spread, which resulted in 21 per cent of all cases involving healthcare workers. This has resulted in a requirement for heathcare staff to adopt a new standard of infection control and personal protection.
WHO declared the outbreak interrupted on 5 July 2003, at which time there had been more than 8,400 cases and approximately 900 deaths. Mainland China reported more than 5,300 cases and 349 deaths. Australia had a single confirmed case of SARS, who had visited New South Wales before the global alert and was detected in retrospect by authorities in her home country. She did not transmit the illness to any of her close contacts.
Five international flights were associated with transmission of SARS. However, there has been no evidence of confirmed transmission on any flights after WHO recommended control measures, including border exit screening.
Reservoir of SARS coronavirus
There has been much interest in determining the source of this new virus, with particular focus on the animal species involved and animal husbandry methods used in southern China. Early investigations have pointed in the direction of certain animal species (palm civet, racoon dog); however, these are not conclusive, and more work in this area needs to be completed.
Mode of transmission of SARS coronavirus
During the SARS outbreak, the predominant mode of transmission of SARS CoV appeared to be direct mucous membrane contact with respiratory droplets from either infected people or fomites.
The evidence to date suggests that spread is predominantly through direct contact or exposure to larger virus-laden droplets, which are thought to travel only 1–2 metres, rather than by lighter airborne particles. It has been postulated that these lighter and smaller aerosols may have been generated by procedures such as nebulisers or intubations, resulting in episodes where significant amplification of transmission was observed.
Infective stool may also pose a transmission risk, but the risks are not yet clear.
New cases occurred primarily in people with close contact with those very ill with SARS, in healthcare and household settings. Less frequently, transmission occurred to casual and social contacts after intense exposure to a case of SARS (in workplaces, aeroplanes or taxis).
Maximum excretion of the virus from the respiratory tract seems to occur near day 10 of illness, and then declines. The efficiency of transmission appears to be greatest following exposure to severely ill patients or those experiencing rapid clinical deterioration, both of which usually occur during the second week of illness.
On reviewing cases of SARS, it was found that, when symptomatic cases were isolated within 5 days following onset of illness, few cases of secondary transmission occurred.
Period of communicability of severe acute respiratory syndrome (SARS)
SARS CoV is not thought to be transmissible during the asymptomatic incubation period, and there has been no evidence that the virus has been spread 10 days after fever has resolved.
Susceptibility and resistance
Older people are more prone to severe disease and pose a particular challenge in the recognition of SARS, as they may present with an afebrile illness, or with a concurrent bacterial sepsis or pneumonia.
In the setting of a SARS outbreak, the diagnosis should be considered for almost any change in health status, even in the absence of typical clinical features of SARS, when such patients have epidemiological risk factors for SARS (for example, close contact with someone suspected to have SARS, or exposure to a location [domestic or international] with documented or suspected recent transmission of SARS CoV).
During the 2003 outbreaks, infants and children accounted for only a small percentage of patients and had much milder disease, with better outcomes. There have been two reported cases of transmission from children to adults, and no reports of transmission from children to other children. Three separate epidemiological investigations have found no evidence of SARS transmission in schools. Furthermore, no evidence of SARS has been found in infants of mothers who were infected during pregnancy. Further investigation is required to determine whether children may have asymptomatic or mild infections.
Control measures for severe acute respiratory syndrome (SARS)
Australian guidelines can be found at the Australian Government website.
There are no vaccines available for SARS CoV.
As a result of the global outbreak of SARS, there has been resurgence in interest and prominence of respiratory hygiene and cough etiquette, to reduce transmission of all forms of respiratory pathogens, including SARS CoV.
This includes encouraging all people with signs and symptoms of a respiratory infection to:
- cover the nose and mouth when coughing or sneezing
- use tissues to contain respiratory secretions
- dispose of tissues in the nearest waste receptacle after use
- wash hands after contact with respiratory secretions, and contaminated objects and materials.
Healthcare facilities should ensure the availability of materials for adhering to respiratory hygiene and cough etiquette in waiting areas for patients and visitors:
- Provide tissues and no-touch receptacles for used tissue disposal.
- Provide conveniently located dispensers for alcohol-based hand rub.
- Provide soap and disposable towels/ or hand dryers for handwashing where sinks are available.
During periods of increased respiratory infection in the community, it may be possible for healthcare facilities to offer surgical masks to people who are coughing and encourage coughing people to sit at least 1 metre away from others in waiting areas.
Healthcare workers should practise droplet precautions, in addition to standard precautions, when examining a patient with symptoms of a respiratory infection.
Once there exists an index of suspicion of SARS, the appropriate infection control measures need to be activated and suitable personal protective equipment (PPE) worn. These will depend on the specific facility involved and the resources available at the time. They include:
- use of standard precautions (that is, hand hygiene), and contact and droplet precautions (that is, use of long-sleeved gowns, gloves and protective eyewear for contact with patient or environment)
- use of airborne precautions that include the use of a P2 (N95 equivalent) mask (respirator) for all people entering the room and, where available, a negative pressure respiratory isolation room (with ensuite)
- restriction of patient movement (and fitting of a surgical mask if they must leave their room)
- avoiding the use of nebulisers, chest physiotherapy, bronchoscopy, gastroscopy or any intervention that may disrupt the respiratory tract
- placing surgical masks over nasal oxygen prongs.
It will become increasingly important for clinicians to elicit epidemiological information from their patients as part of normal history taking. Travel history, recent attendance at hospitals or exposure to others who are ill may assist in the refinement of a patient’s differential diagnosis and associated risk.
The following points may become appropriate to consider in the primary care setting as a means of managing the issues of SARS:
- Signage at the reception desk may advise potential cases to report their concerns to the practice as early as possible.
- Any case that could be reasonably regarded as possibly SARS should be discretely offered a mask and diverted out of the waiting room and into a single room (for example, returned travellers from an affected region with SARS-like symptoms).
- If seen in the practice, the clinician should close the door, open a window, turn off the air-conditioning, and put on a mask (N2 if possible), gown, gloves and eye protection.
- Wash hands after consultation.
- Do not self-contaminate by touching one’s own mucous membranes with contaminated hands.
- Make an assessment and call the Communicable Diseases Section of the department for an update of the SARS situation and to develop a suitable management strategy.
- Where possible, any cases of concern should be seen at home with the appropriate PPE.
Control of case
Suspected cases will be managed on their clinical merits, with home care regarded as a suitable option if the domestic situation, including its suitability in terms of infection control, is judged to be adequate. In such circumstances, cases will be advised to voluntarily restrict their movements.
Probable and confirmed cases will require hospitalisation and isolation in a suitable health facility, which will be determined by the Communicable Diseases Section of the department in consultation with the treating clinician. The receiving hospital will activate its SARS protocol to suitably manage such a patient.
All suspected, probable and confirmed cases will be excluded from school and work until clearance is obtained from the department.
There are no specific treatment recommendations for SARS. The application of intensive supportive therapy and empirical antimicrobial therapy, to cover other infective agents, is the usual approach. Antiviral and pulse steroid therapy have been used in the past in different countries, with varying degree of success.
Discontinuation of SARS isolation precautions
SARS isolation precautions should be discontinued only after consultation with the local public health authorities and the evaluating clinician.
Control of contacts
Only people who have been close to an unwell person with SARS are at any significant risk of acquiring infection. For this reason, only close contacts are sought when public health contact tracing measures are implemented to control disease spread. A close contact is a person who has lived, worked or had other dealings with a SARS case that have caused them to be within 1 metre of the case, or a person who has had direct contact with respiratory secretions from a case while not wearing PPE.
Contact tracing will be undertaken for close contacts of probable cases of SARS who were exposed after the patient became symptomatic. Contact tracing will not be undertaken for suspected cases of SARS while SARS has not been locally transmitted in Australia.
The aims of contact tracing are to find, provide information to and manage people who may have been exposed to SARS CoV, and who may be incubating or have early signs of the disease. Management of these contacts depends on who they were exposed to and the circumstances surrounding the exposure.
Well close contacts will be placed under either passive or active surveillance. Unwell close contacts of probable cases will be placed under active surveillance and isolated in an appropriate setting.
It should be remembered that one of the most important available measures to prevent the spread of SARS CoV is the application of respiratory precautions and scrupulous handwashing. Contacts should be advised of such and also for the need to seek immediate medical attention if they develop the initial symptoms of SARS. Daily temperature monitoring for 10 days after a break in exposure from the SARS case is advisable.
Close contacts of cases or returned travellers from regions of SARS outbreak, as defined by the department, will be allowed to attend school provided that they remain completely asymptomatic. Such people should measure their temperatures daily to ensure that fever is not present during the 10-day incubation period.
Cleaning and disinfection
Early studies of SARS CoV showed that, if uninterrupted by cleaning or disinfectants, the virus can survive on surfaces in the environment, such as stainless steel benches, plastic, wood or cotton, for 12–72 hours. However, the virus is not difficult to kill. It is important to clean surfaces with detergent and water, and then to disinfect them. Remember that disinfectants need the appropriate time at the appropriate concentration to be effective.
The different methods available for disinfecting include the following:
- Heat (56 °C) is very effective, so dishes, linen and other washable items can be disinfected by washing in hot water and detergent.
- Alcohol is effective. Tests show that 75 per cent ethanol kills the virus at room temperature in less than 5 minutes. Slightly lower concentrations of alcohol would take a slightly longer time. Alcohol can be found in alcohol rubs (for hands), alcohol-impregnated wipes and swabs (such as those used to disinfect skin), and methylated spirits.
- Acetone is effective; 10 per cent acetone will kill the virus in less than 5 minutes.
- Phenol (2 per cent) is effective and may be found in some hospital-grade disinfectants.
- Bleach has not yet been tested against SARS CoV. However, bleach is an effective disinfectant for many other viruses and is likely to be effective. Surfaces to be disinfected with bleach must first be cleaned with detergent and water. An appropriate dilution of 1 in 100 of most household bleach preparations provides sodium hypochlorite at 500 ppm.
Reviewed 08 October 2015