Severe Acute Respiratory
Syndrome (SARS) is a disease of unknown etiology that
has been described in patients in Asia, North America,
and Europe. The information in this report provides a
summary of the clinical characteristics of SARS patients
treated in Hong Kong Special Administrative Region
(China), Taiwan (China), Thailand, Singapore, the United
Kingdom, Slovenia, Canada and the United States since
mid-February 2003. This information is preliminary and
subject to limitations because of the broad and
non-specific case definition.
Most patients identified
as of March 21, 2003 have been previously healthy adults
aged 25-70 years. A few suspected cases of SARS have
been reported among children (≤15 years).
The incubation period of
SARS is usually 2-7 days but may be as long as 10 days.
The illness generally begins with a prodrome of fever
(>38°C), which is often high, sometimes associated with
chills and rigors and sometimes accompanied by other
symptoms including headache, malaise, and myalgias. At
the onset of illness, some cases have mild respiratory
symptoms. Typically, rash and neurologic or
gastrointestinal findings are absent, although a few
patients have reported diarrhoea during the febrile
prodrome.
After 3-7 days, a lower
respiratory phase begins with the onset of a dry,
non-productive cough or dyspnea that may be accompanied
by or progress to hypoxemia. In 10%-20% of cases, the
respiratory illness is severe enough to require
intubation and mechanical ventilation. The case fatality
among persons with illness meeting the current WHO case
definition for probable and suspected cases of SARS is
around 3%.
Chest radiographs may be
normal during the febrile prodrome and throughout the
course of illness. However, in a substantial proportion
of patients, the respiratory phase is characterized by
early focal infiltrates progressing to more generalized,
patchy, interstitial infiltrates. Some chest radiographs
from patients in the late stages of SARS have also shown
areas of consolidation.
Early in the course of
disease, the absolute lymphocyte count is often
decreased. Overall white cell counts have generally been
normal or decreased. At the peak of the respiratory
illness, up to half of patients have leukopenia and
thrombocytopenia or low-normal platelet counts (50,000 –
150,000 / μl). Early in the respiratory phase, elevated
creatine phosphokinase levels (up to 3000 IU / L) and
hepatic transaminases (2- to 6-times the upper limits of
normal) have been noted. Renal function has remained
normal in the majority of patients.
Treatment regimens have
included a variety of antibiotics to presumptively treat
known bacterial agents of atypical pneumonia. In several
locations, therapy has also included antiviral agents
such as oseltamivir or ribavirin. Steroids have also
been given orally or intravenously to patients in
combination with ribavirin and other antimicrobials. At
present, the most efficacious treatment regime, if any
is unknown.
|