(This advisory has had minor edits for local distribution by Public Health - Seattle & King County.)
Update on Influenza A (H5N1) and SARS: Interim Recommendations for Enhanced U.S. Surveillance, Testing, and Infection Control
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 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 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
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| 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).
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| Testing for influenza A (H5N1) should be considered on a case-by-case basis (see information on testing, below) 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. |
Report suspected cases of influenza H5N1 immediately to Public Health at 206-296-4774.
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:
