1 table omitted
Since late February 2003, CDC has been supporting the World Health Organization
(WHO) in the investigation of a multicountry outbreak of atypical pneumonia
of unknown etiology. The illness is being referred to as severe acute respiratory
syndrome (SARS). This report describes the scope of the outbreak, preliminary
case definition, and interim infection control guidance for the United States.
On February 11, the Chinese Ministry of Health notified WHO that 305
cases of acute respiratory syndrome of unknown etiology had occurred in six
municipalities in Guangdong province in southern China during November 16,
2002–February 9, 2003. The disease was characterized by transmission
to health-care workers and household contacts; five deaths were reported.1 On February 26, a man aged 47 years who had traveled in mainland China
and Hong Kong became ill with a respiratory illness and was hospitalized shortly
after arriving in Hanoi, Vietnam. Health-care providers at the hospital in
Hanoi subsequently developed a similar illness. The patient died on March
13 after transfer to an isolation facility in Hong Kong. During late February,
an outbreak of a similar respiratory illness was reported in Hong Kong among
workers at another hospital; this cluster was linked to a patient who had
traveled previously to southern China. On March 12, WHO issued a global alert
about the outbreak and instituted worldwide surveillance.
As of March 19, WHO has received reports of 264 patients from 11 countries
with suspected and probable* SARS. Areas with reported local transmission
include Hong Kong and Guangdong province, China; Hanoi, Vietnam; and Singapore.
More limited transmission has been reported in Taipei, Taiwan, and Toronto,
Canada. The initial cases reported in Singapore, Taiwan, and Toronto were
among persons who all had traveled to China.
On March 15, after issuing a preliminary case definition for suspected
cases (see sidebar), CDC initiated enhanced domestic surveillance for SARS.
CDC also issued a travel advisory suggesting that persons planning nonessential
travel to Hong Kong, Guangdong, or Hanoi consider postponing their travel
March 16, CDC began advising passengers arriving on direct flights from these
three locations to seek medical attention if they have symptoms of febrile
respiratory illness. As of March 18, approximately 12,000 advisory notices
had been distributed to airline passengers. In addition, surveillance is being
heightened for suspected cases of SARS among arriving passengers. As of March
19, a total of 11 suspected cases of SARS in the United States are under investigation
by CDC and state health authorities.
Among patients reported worldwide as of March 19, the disease has been
characterized by rapid onset of high fever, myalgia, chills, rigor, and sore
throat, followed by shortness of breath, cough, and radiographic evidence
of pneumonia. The incubation period has generally been 3-5 days (range: 2-7
days). Laboratory findings have included thrombocytopenia and leukopenia.
Many patients have had respiratory distress or severe pneumonia requiring
hospitalization, and several have required mechanical ventilation. Of the
264 suspected and probable cases reported by WHO, nine (3%) persons have died.
In addition, secondary attack rates of >50% have been observed among health-care
workers caring for patients with SARS in both Hong Kong and Hanoi. Additional
clinical and epidemiologic details are available from WHO at http://www.who.int/wer/pdf/2003/wer7812.pdf.
In the United States, initial diagnostic testing for persons with suspected
SARS should include chest radiograph, pulse oximetry, blood cultures, sputum
Gram stain and culture, and testing for viral respiratory pathogens, particularly
influenza types A and B and respiratory syncytial virus. Clinicians should
save any available clinical specimens (e.g., respiratory samples, blood, serum,
tissue, and biopsies) for additional testing until diagnosis is confirmed.
Instructions for specimen collection are available from CDC at http://www.cdc.gov/ncidod/sars/pdf/specimencollection-sars.pdf. Specimens should be forwarded to CDC by state health departments after
consultation with the SARS State Support Team at the CDC Emergency Operations
Clinicians evaluating suspected cases should use standard precautions
(e.g., hand hygiene) together with airborne (e.g., N-95 respirator) and contact
(e.g., gowns and gloves) precautions (http://www.cdc.gov/ncidod/sars/infectioncontrol.htm). Until the mode of transmission has been defined more precisely, eye
protection also should be worn for all patient contact. As more clinical and
epidemiologic information becomes available, interim recommendations will
CDC SARS Investigative Team; AT Fleischauer, PhD, EIS Officer, CDC.
During 2000, approximately 83 million nonresident passengers arrived
in China, 13 million in Hong Kong, and 2 million in Vietnam, and approximately
460,000 residents of China, Hong Kong, and Vietnam traveled to the United
States.2 During January 1, 1997–March 18, 2003, an estimated
5% of ill tourists worldwide who sought post-travel care from one of 35 worldwide
GeoSentinel travel clinics had pneumonia (International Society of Tropical
Medicine, unpublished data, 2003). In the United States, approximately 500,000
persons with pneumonia require hospitalization each year; in approximately
half of these cases, no etiologic agent is identified despite intensive investigation.3,4 On the basis of these data and the broad and necessarily nonspecific
case definition, cases meeting the criteria for SARS are anticipated worldwide
and in the United States. However, most of the anticipated cases are expected
to be unrelated to the current outbreak.
Electron microscopic identification of paramxyovirus-like particles
has been reported from Germany and Hong Kong.5 This family of viruses
includes measles, mumps, human parainfluenza viruses, and respiratory syncytial
virus in addition to the recently identified henipaviruses and metapneumovirus.
Additional testing is under way to confirm a definitive etiology. Identification
of the causative agent should lead to specific diagnostic tests, simplify
surveillance, and focus treatment guidelines and infection control guidance.
Clinicians and public health officials who suspect cases of SARS are
requested to report such cases to their state health departments. CDC requests
that reports of suspect cases from state health departments, international
airlines, cruise ships, or cargo carriers be directed to the SARS Investigative
Team at the CDC Emergency Operations Center, telephone 770-488-7100. Additional
information about SARS (e.g., infection control guidance and procedures for
reporting suspected cases) is available at http://www.cdc.gov/ncidod/sars. Global case counts are available at http://www.who.int.
Respiratory illness of unknown etiology with onset since February 1,
2003, and the following criteria:
Documented temperature >100.4°F (>38.0°C)
One or more symptoms of respiratory illness (e.g., cough, shortness
of breath, difficulty breathing, or radiographic findings of pneumonia or
acute respiratory distress syndrome)
Close contact† within 10 days of onset of symptoms with
a person under investigation for or suspected of having SARS or travel within
10 days of onset of symptoms to an area with documented transmission of SARS
as defined by the World Health Organization (WHO).
*As of March 19, 2003.
†Defined as having cared for, having lived with, or having had
direct contact with respiratory secretions and/or body fluids of a person
suspected of having SARS.
References: 5 available
*Suspected cases (see sidebar) with either a) radiographic evidence
of pneumonia or respiratory distress syndrome or b) evidence of unexplained
respiratory distress syndrome by autopsy are designated probable cases by
the WHO case definition.
Outbreak of Severe Acute Respiratory Syndrome—Worldwide, 2003. JAMA. 2003;289(14):1775–1776. doi:10.1001/jama.289.14.1775