Update on SARS and Avian
Influenza A (H5N1)
This update reviews the current situation and
the surveillance and diagnostic recommendations for both severe acute
respiratory syndrome (SARS) and avian influenza A (H5N1). The updates have been
combined because the clinical presentation and travel history of persons with
avian influenza A (H5N1) or SARS coronavirus (SARS-CoV) infection may overlap.
The recommendations for SARS have been revised downward because the most recent
SARS activity in China has been contained. The recommendations for avian influenza A
(H5N1) remain at the enhanced level established in February 2004. As detailed in the recommendations
below, vigilance in the clinical setting for SARS and avian influenza (H5N1)
requires that health-care providers consistently obtain international travel
and other exposure risk information for persons who have specified respiratory
symptoms.
SEVERE ACUTE RESPIRATORY SYNDROME
Current Situation
During April 22-29, 2004, the Chinese Ministry of Health (MOH) reported
a total of nine cases (one fatal) of SARS in China; seven of the patients were from Beijing, and two were from Anhui Province, located in
east-central China. Two of the nine
patients were graduate students who worked at National Institute of Virology
Laboratory (NIVL) in Beijing, which is known to conduct research on SARS-CoV. The NIVL was
closed on April 23 and remains closed to date. Possible sources of infection
for the two laboratory workers, neither of whom is known to have worked
directly with SARS-CoV, are being investigated. Of the seven other SARS cases,
two were directly linked to close contact with one of the graduate students who
worked at NIVL; these two cases were in the graduate student’s mother (who
died) and in a nurse who provided care to the graduate student. The remaining
five cases were linked to close contact with the nurse.
No further cases of SARS in China or anywhere else in the world have been
reported since April 29, 2004. On May 18, the World Health Organization (WHO) reported
on its website that the outbreak in China appears to have been contained, but that
laboratory biosafety concerns remain and further investigation is under way.
CDC is in close communication with WHO and is working with its other public
health partners to reinforce the need for strict adherence to applicable
biosafety precautions to reduce the risk of laboratory-related exposures to
SARS-CoV.
Recommended U.S. SARS Control Measures
Given that the recent SARS outbreak in China appears to have been contained with relatively limited
secondary transmission, CDC is revising previously issued guidance for enhanced
surveillance of SARS in travelers to China (http://www.cdc.gov/ncidod/sars/han/han_China042304.htm).
In the current setting, surveillance efforts should
aim to identify patients who 1) require hospitalization for radiographically
confirmed pneumonia or acute respiratory distress syndrome without identifiable
etiology AND 2) have one of the following risk factors in the 10 days before
the onset of illness:
a. Travel to mainland China, Hong Kong, or Taiwan, or close contact with
an ill person with a history of recent travel to one of these areas, OR
b. Employment in an occupation
associated with a risk for SARS-CoV exposure (e.g., health-care worker with
direct patient contact; worker in a laboratory that contains live SARS-CoV), OR
c. Part of a cluster of cases of
atypical pneumonia without an alternative diagnosis.
When individuals meeting these criteria are identified,
appropriate infection control should be instituted, as described in the
guidelines at www.cdc.gov/ncidod/sars/absenceofsars.htm. Diagnostic
testing should be performed judiciously, and preferably only in consultation
with the local or state health department. SARS-CoV testing should be
considered if no alternative diagnosis is identified 72 hours after initiation
of the clinical evaluation and the patient is thought to be at high risk for
SARS-CoV disease (e.g., part of a cluster of unexplained pneumonia cases).
Infection control practioners and other health-care personnel also should be
alert for clusters of pneumonia among two or more health-care workers who work
in the same facility.
Additional SARS Information
For more information about current U.S. SARS control
guidelines, see the CDC document, “In the Absence of SARS-CoV Transmission
Worldwide: Guidance for Surveillance, Clinical and Laboratory Evaluation, and
Reporting” at http://www.cdc.gov/ncidod/sars/absenceofsars.htm. Additional information about SARS preparedness is
available in CDC’s document, Public Health Guidance for Community-Level
Preparedness and Response to Severe Acute Respiratory Syndrome (SARS) http://www.cdc.gov/ncidod/sars/sarsprepplan.htm; general information about SARS is available at http://www.cdc.gov/ncidod/sars/.
AVIAN INFLUENZA A (H5N1)
Current Situation
Since January 2004, a total of 34 confirmed human cases of avian
influenza A (H5N1) virus infections have been reported in Vietnam (22 cases, 15
deaths) and Thailand (12 cases, 8 deaths). The last case officially reported
by Vietnam occurred in February 2004. One
additional case was described in several media reports in mid-March in southern
Vietnam http://www.who.int/csr/don/2004_03_22a/en/.
All persons with confirmed H5N1 influenza had severe illness and were
hospitalized with pneumonia; most cases occurred in children and young adults
who had direct close contact with live, sick, or dead poultry. There currently
is no evidence of efficient human-to-human transmission of avian influenza A
(H5N1) viruses. These cases were associated with widespread H5N1 poultry
outbreaks that occurred at commercial and small backyard poultry farms. Since
December 2003, eight countries have reported H5N1 outbreaks among poultry.
Outbreaks in South
Korea and Japan were limited to commercial farms
and have been adequately contained; however, outbreaks in Vietnam, Thailand, Indonesia, Cambodia, Laos, and China have been more extensive and the degree to which they have
been controlled remains uncertain. On the basis of current information, human
infection with avian influenza A (H5N1) viruses remains a public health risk in
these countries.
Enhanced U.S. Surveillance, Diagnostic Evaluation, and Infection Control
Precautions for Avian Influenza
A (H5N1)
CDC recommends maintaining the enhanced surveillance efforts
by state and local health departments, hospitals, and clinicians to identify
patients at increased risk for avian influenza A (H5N1) that were issued by CDC
on February 3, 2004 http://www.cdc.gov/flu/han020302.htm. Guidelines for enhanced surveillance are:
Testing for avian influenza A (H5N1) is indicated for hospitalized
patients with:
a. Radiographically
confirmed pneumonia, acute respiratory distress syndrome (ARDS), or other
severe respiratory illness for which an alternate diagnosis has not been
established, AND
b. History of travel
within 10 days of symptom onset to a country with documented H5N1 avian
influenza in poultry and/or humans (for a listing of H5N1-affected countries,
see the OIE Web site at http://www.oie.int/eng/en_index.htm
and the WHO Web site at http://www.who.int/en/).
Testing for avian influenza A (H5N1) should be considered on a
case-by-case basis in consultation with state and local health departments for
hospitalized or ambulatory patients with:
a. Documented
temperature of >38°C (>100.4°F), AND
b. One or more of the
following: cough, sore throat, shortness of breath, AND
b. History of contact
with poultry (e.g., visited a poultry farm, a household raising poultry, or a
bird market) or a known or suspected human case of influenza A (H5N1) in an
H5N1-affected country within 10 days of symptom onset.
Infection control precautions for H5N1 remain unchanged from the CDC
interim recommendations published on February 3, 2004 http://www.cdc.gov/flu/han020302.htm.
These recommendations are further described in the CDC guidance document,
“Interim Recommendations for Infection Control in Health-Care Facilities Caring
for Patients with Known or Suspected Avian Influenza” http://www.cdc.gov/flu/avian/professional/infect-control.htm.
Additional Avian Influenza A (H5N1) Information
· For information about reported
outbreaks of avian influenza A (H5N1) among poultry, see the web site of the World
Organization of Animal Health (OIE) at http://www.oie.int/eng/AVIAN_INFLUENZA/home.htm.
· For information about human H5N1
cases, see the WHO web site http://www.who.int/en/
· For clinical information about human
H5N1 cases, see:
o CDC. Cases of influenza A (H5N1) – Thailand, 2004. MMWR 2004;53:100-103 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5305a2.htm.
o Hien TT, Liem AT, Dung NT, et al. Avian influenza A (H5N1) in 10
patients in Vietnam. New England Journal of Medicine 2004;350:1179-1188.
For general information about influenza, see the CDC Web site at www.cdc.gov/flu.
