Severe Acute Respiratory Syndrome (SARS)

NATURAL HISTORY

The incubation period for SARS is 2-7 days, most commonly 3-5 days.

As best we know, the syndrome begins with fever for 1-2 days, then cough for 2-3 days. Atypical pneumonia develops on day 4-5.

From here, the disease takes 1 of 2 courses:

A) the patient improves (80-90% of cases); or

B) the patient deteriorates severely on day 6-7 (10-20% of cases).

50% of type B cases die, giving an overall Case Fatality Rate of 5-10%. Risk factors for poor outcome are not clear, apart from the severe type of illness. SARS affects predominantly adults. Very few cases have occurred in children or the elderly.

INVESTIGATIONS

Full blood count shows neutropenia. Chest X-rays changes are consistent with atypical pneumonia.

TREATMENT

Treatment is purely supportive therapy and isolation. Cases need to be in the best isolation facility you can arrange (this will vary for Pacific Island countries) and must be nursed using strict barrier techniques including gown or preferably overalls, gloves, boots or over-shoes, HEPA or N95-100 mask (or at least a surgical mask if nothing else available) and goggles - not pleasant to use in Pacific Island countries climate! Isolation may be individual or as a cohort of compatible cases. Compatible and suspected cases MUST be nursed SEPARATELY, and suspected cases must NEVER be placed with other patients for observation.

There is extremely high risk to attending medical and nursing staff and to close family contacts. Risk to casual contacts is not high unless the patient is extremely ill. Attack rates among health care workers have been lowest in facilities where they know what they are doing and practice the best isolation and infection control they can; if this is slack, attack rates (and outcomes) are very bad.

Medical or nursing staff should take specimens to minimise the number of people exposed (ie lab workers). Consider a special cohort of doctor(s) and nurses who only look after suspected SARS cases and remain quarantined at the hospital.

During assessment in the clinic or outpatient department or during transport, reverse barrier nursing is an option (ie the patient wears the gown and mask).

Patients need good fluid management, antipyretics (paracetamol, not aspirin, as some cases have thrombocytopenia and a couple in Hong Kong actually got disseminated intravascular coagulation), and oxygen if respiratory difficulties become worse. Type b cases need artificial ventilation. Any respiratory signs warrant broad spectrum antibiotic prophylaxis against bacterial secondary infection.

There is no specific treatment identified yet. People are trying ribavirin and even tetracycline, but there are no clear-cut results yet. Influenza drugs (Ramiflu, Relenza) seem not to be beneficial. In severe pneumonia, intravenous steroids seem helpful.

DISCHARGE

Discharge criteria for recovered patients are still being worked out. Probably 2 days without fever or respiratory symptoms, and white cell count and platelet counts returning to normal, would be reasonable. We expect the chest X-ray signs may persist for days to weeks (as with other atypical pneumonias) so no need to wait for a clear chest X-ray.

Source: PacNet, the discussion list of the Pacific Public Health Surveillance Network (PPHSN)