Issued
as Health Alert Network message on February 2, 2004, 9:00
AM EST
Recent Developments
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 inconclusive.
Interim Recommendations: Enhanced U.S. Surveillance and
Diagnostic Evaluation
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 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 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
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
Influenza A(H5N1)
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
contact
- Eye protection
- Wear when within 3 feet of the patient
- Airborne Precautions
- 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 the room.
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.
More Information
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 Jan 14.
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