CDC Issues Infection Control Precautions for Bird Flu
Agency recommends U.S. health officials keep watch for SARS
and bird flu
The U.S. Centers for Disease Control and Prevention (CDC)
issued an advisory February 3 for medical professionals to
be watchful for avian influenza and severe acute respiratory
syndrome (SARS) in their patients. The agency also advised
health care practitioners to question patients showing flu-like
symptoms about possible recent travel to Asia where the two
diseases have appeared most frequently.
Since the release of the CDC advisory February 3, the World
Health Organization (WHO) has updated the confirmed number
of bird flu cases that have appeared in humans. As of February
4, WHO reports 17 human cases of the disease, and 13 of those
patients have died. All the human occurrences have been in
either Vietnam or Thailand.
Following is the text of the CDC advisory:
Department of Health and Human Services
U.S. Centers for Disease Control and Prevention
Update on Influenza A(H5N1) and SARS: Interim Recommendations
for Enhanced U.S. Surveillance, Testing, and Infection Control
February 3, 2004
Influenza A(H5N1) Virus Infections
Infections of H5N1 among poultry have been confirmed in Cambodia,
China, Hong Kong SAR, Indonesia, Japan, Korea, Laos, Thailand,
and Vietnam (for a continually updated listing of affected
countries, visit the Web site of the World Organization of
Animal Health [OIE] at http://www.oie.int/eng/en_index.htm).
Human cases of influenza A(H5N1) infection have occurred in
Vietnam and Thailand. On February 1, 2004, the World Health
Organization (WHO) reported that laboratory test results had
confirmed two new cases of human H5N1 infection in Vietnam;
both patients died. The cases were in two sisters who are part
of a cluster of four cases of severe respiratory illness in
a single family. A detailed investigation of this cluster is
under way; limited human-to-human transmission may be one possible
explanation, but direct poultry-to-human transmission cannot
be ruled out, according to WHO. To date, 10 laboratory-confirmed
cases of H5N1 infection have been reported in patients in Vietnam,
8 of whom died. In Thailand, cases of H5N1 infection have been
confirmed in 4 persons, 3 of whom died. Laboratory results
on additional possible cases are pending. (For updated information,
visit the WHO Web site at http://www.who.int/en/).
With the exception of the family cluster in Vietnam, it is
believed that all human H5N1 cases resulted from contact with
infected birds or surfaces contaminated with excretions from
infected birds. At this time, there is no evidence of efficient
person-to-person transmission in Vietnam or elsewhere.
Genetic sequencing of H5N1 viruses from human cases in Vietnam
indicates that all genes are of avian origin. (The acquisition
of human influenza viral genes increases the likelihood that
a virus of avian origin can be readily transmitted from person-to-person.)
Genetic sequencing of human H5N1 isolates from Vietnam additionally
showed characteristics commonly known to confer antiviral resistance
to amantadine and rimantadine, two antiviral drugs used for
influenza. The remaining two antivirals (oseltamivir and zanamavir)
should still be effective.
Severe Acute Respiratory Syndrome
On January 31, 2004, WHO announced that a new case of laboratory-confirmed
infection with SARS-associated coronavirus (SARS-CoV) had been
reported in China. This is the fourth SARS case (three confirmed,
one probable) reported in China since December 16, 2003.
The most recent case occurred in a 40-year-old director of
a hospital and practicing physician in Guangzhou, Guangdong
Province, China. He became ill with SARS-like symptoms on January
7, 2004, and was admitted to a hospital with pneumonia on January
16 and placed in isolation. Previously reported confirmed cases
include a 20-year-old woman who worked in a restaurant in Guangdong
Province and became ill on December 25, 2003, and a 32-year-old
man in Guangdong Province who had become ill on December 16,
2003. A fourth person (probable case) -- a 35-year-old business
man from the Guangdong Province who had onset of illness on
December 31, 2003 - tested positive for SARS-CoV infection
at a national reference laboratory in China and on preliminary
serologic tests performed by WHO SARS International Reference
and Verification Network laboratories in Hong Kong.
All four patients have recovered from their illness and have
been discharged from the hospital. To date, none of the contacts
of these cases has developed a SARS-like illness. The source
of infection in these individuals has not been determined.
Samples collected from cages that housed civets at the restaurant
where the waitress with confirmed SARS worked have tested positive
for traces of SARS-CoV, suggesting a possible source of infection.
However, evidence that civets transmit SARS-CoV to humans remains
Interim Recommendations: Enhanced U.S. Surveillance and Diagnostic
CDC recommends enhanced surveillance efforts by state and
local health departments, hospitals, and clinicians to identify
patients at increased risk for influenza A(H5N1) and SARS.
The clinical presentation and travel history of persons with
influenza A(H5N1) or SARS-CoV infection may overlap. Interim
recommendations for diagnostic evaluation for these agents
in individuals who meet certain epidemiologic and clinical
criteria follow below.
Influenza A(H5N1) Virus Infections
Testing for influenza A(H5N1) is indicated for hospitalized
a. radiographically confirmed pneumonia, acute respiratory
distress syndrome (ARDS), or other severe respiratory illness
for which an alternate diagnosis has not been established,
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 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),
b. one or more of the following: cough, sore throat, shortness
c. history of contact with domestic poultry (e.g., visited
a poultry farm, household raising poultry, or bird market)
or a known or suspected human case of influenza A(H5N1) in
an H5N1-affected country within 10 days of symptom onset.
Severe Acute Respiratory Syndrome
CDC continues to recommend consideration of testing for SARS-CoV
in patients who require hospitalization for radiographically
confirmed pneumonia or ARDS without identifiable etiology AND
who have one of the following risk factors in the 10 days before
the onset of illness:
--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
--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
--Part of a cluster of cases of atypical pneumonia without
an alternative diagnosis.
For patients with pneumonia or ARDS who have recently traveled
to Guangdong Province, China, diagnostic testing for SARS-CoV
should be performed immediately. For other patients, diagnostic
testing for SARS should proceed for such patients as described
in guidelines at www.cdc.gov/ncidod/sars/absenceofsars.htm.
Interim Recommendations: Infection Control Precautions for
All patients who present to a health-care setting with fever
and respiratory symptoms should be managed according to recommendations
for Respiratory Hygiene and Cough Etiquette and questioned
regarding their recent travel history. Isolation precautions
identical to those recommended for SARS should be implemented
for all hospitalized patients diagnosed with or under evaluation
for influenza A(H5N1) as follows:
--Standard Precautions: Pay careful attention to hand hygiene
before and after all patient contact
--Contact Precautions: Use gloves and gown for all patient
--Eye protection: Wear when within 3 feet of the patient
--Place the patient in an airborne isolation room (i.e., monitored
negative air pressure in relation to the surrounding areas
with 6 to 12 air changes per hour).
--Use a fit-tested respirator, at least as protective as a
NIOSH-approved N-95 filtering facepiece respirator, when entering
For additional information regarding these and other health-care
isolation precautions, see the Guidelines for Isolation Precautions
in Hospitals. These precautions should be continued for 14
days after onset of symptoms until an alternative diagnosis
is established or until diagnostic test results indicate that
the patient is not infected with influenza A virus (see Laboratory
Testing Procedures below). Patients managed as outpatients
or hospitalized patients discharged before 14 days should be
isolated in the home setting on the basis of principles outlined
for the home isolation of SARS patients (see http://www.cdc.gov/ncidod/sars/guidance/i/pdf/i.pdf).
Laboratory Testing Procedures
Highly pathogenic avian influenza A(H5N1) is classified as
a select agent and must be worked with under Biosafety Level
(BSL) 3+ laboratory conditions. This includes controlled access
double door entry with change room and shower, use of respirators,
decontamination of all wastes, and showering out of all personnel.
Laboratories working on these viruses must be certified by
the U.S. Department of Agriculture. The same BSL 3+ laboratory
guidelines are recommended for conducting virus isolation for
SARS-CoV. CDC does not recommend that virus isolation studies
on respiratory specimens from patients who meet the above criteria
be conducted unless stringent BSL 3+ conditions can be met.
Therefore, respiratory virus cultures should not be performed
in most clinical laboratories and such cultures should not
be ordered for patients suspected of having H5N1 infection.
Clinical specimens from suspect A(H5N1) cases and SARS-CoV
cases may be tested by PCR assays using standard BSL 2 work
practices in a Class II biological safety cabinet. In addition,
commercial antigen detection testing can be conducted under
BSL 2 levels to test for influenza.
To assist public health public health laboratories with SARS
and respiratory illness diagnostic preparedness efforts, CDC
has developed real-time PCR protocols for a number of respiratory
pathogens, including influenza A and B viruses, adenovirus,
metapneumovirus, Legionella, Chlamydia pneumoniae, and Mycoplasma
pneumoniae. These protocols are currently available only to
public health laboratories and have been posted at the APHL
Members Only (password required) Web site www.aphl.org/Members_Only/index.cfm,
under SARS. These protocols are not available in all public
health laboratories, and physicians should consult with their
local public health laboratory when ordering these tests.
Specimens from persons meeting the above clinical and epidemiologic
criteria should be sent to CDC if
--The specimen tests positive for influenza A by PCR or by
antigen detection testing, OR
--PCR assays for influenza or SARS-CoV are not available at
the state public health laboratory.
Because the sensitivity of commercially available rapid diagnostic
tests for influenza may not always be optimal, CDC also will
accept specimens from persons meeting the above clinical criteria
even if they test negative by influenza rapid diagnostic testing
if PCR assays are not available at the state laboratory.
Requests for testing should come through the state and local
health departments, which should contact the CDC Director's
Emergency Operations Center at 770-488-7100 before sending
specimens for influenza A(H5N1) or SARS testing.
For further details about the reported cases of influenza
A(H5N1) in Asia, see the WHO Web site. Additional information
about influenza is available on the CDC Web site at www.cdc.gov/flu.
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 www.cdc.gov/ncidod/sars/absenceofsars.htm.
The document is part of CDC's draft Public Health Guidance
for Community-Level Preparedness and Response to Severe Acute
Respiratory Syndrome (SARS) www.cdc.gov/ncidod/sars/sarsprepplan.htm.
For the previous HAN update, see the CDC Health Update for