Issued as Health Alert Network message
on August 12, 2004, 6:22 PM EST
CDC Health Update
This update reviews the current situation and the surveillance and diagnostic
recommendations for avian influenza A (H5N1). 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 avian influenza (H5N1) requires that health-care providers
consistently obtain international travel and other exposure risk information
for persons who have specified respiratory symptoms.
Current Situation
On August 12, 2004, the Vietnamese Ministry
of Health officially reported to the World
Health Organization (WHO)
three human deaths from confirmed avian influenza
H5 infection. Additional tests are needed
to determine whether the virus belongs to
the same H5N1 strain that caused 22 cases
(15 deaths) in Vietnam and 12 cases (8 deaths)
in Thailand earlier this year.
Cambodia, China, Indonesia, Japan, Laos,
South Korea, Thailand, and Vietnam were previously
affected by widespread H5N1 outbreaks in poultry
during early 2004. At that time, more than
100 million birds either died from the disease
or were culled (killed) in efforts to contain
the outbreaks. Human cases (34 in all) were
reported only in Thailand and Vietnam. The
last case officially confirmed and reported
to the WHO by Vietnam occurred in February
2004.
Beginning in late June 2004, however, new
lethal outbreaks of highly pathogenic avian
influenza A (H5N1) among poultry were reported
to the World Organization for Animal Health
(OIE) by China, Indonesia, Thailand, and Vietnam.
The deaths reported by Vietnam on August 12
are the first reported human cases associated
with this second wave of H5N1 infection among
poultry. CDC is in communication with WHO
and will continue to monitor the situation.
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 (see www.cdc.gov/flu/han020302.htm).
Guidelines for enhanced surveillance are:
Testing for avian influenza A (H5N1) is indicated
for hospitalized patients with:
- Radiographically confirmed pneumonia,
acute respiratory distress syndrome
(ARDS), or other severe respiratory illness
for which an alternate diagnosis has not
been established, AND
- History of travel within 10 days of
symptom onset to a country with documented
H5N1 avian influenza in poultry and/or
humans (for a regularly updated listing
of H5N1-affected countries, see the OIE Web site and
the WHO Web site).
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:
- Documented temperature of >38°C
(>100.4°F), AND
- One or more of the following: cough,
sore throat, shortness of breath,
AND
- 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.
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."
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.
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 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.
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 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 (404) 639-3747 or (404) 639-3591
and ask for the epidemiologist on call before
sending specimens for influenza A (H5N1) testing.
Additional Avian Influenza A (H5N1) Information
Categories of Health Alert messages:
Health Alert conveys the highest level of importance; warrants immediate action
or attention.
Health Advisory provides important information for a specific incident or
situation; may not require immediate action.
Health Update provides updated information regarding an incident or situation;
unlikely to require immediate action.
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