The Center for Disease manage and ...

The Center for Disease manage and Prevention (CDC) has released interim recommendations for evaluating and reporting suspected cases of avian influenza A (H5N1) The recommendations are available online at http://www.cdc.gov/mmwr/preview/ mmwrhtml/mm5305a1.htm.

During December 2003 and February 2004 outbreaks of highly pathogenic avian influenza A among domestic fowls were reported in Cambodia, China, Indonesia, Japan, Laos, southward Korea, Thailand, and Vietnam. As of February 9 2004 23 cases of laboratory-confirmed influenza A virus infections in humans, resulting in 18 deaths, had been reported in Thailand and Vietnam. In addition, approximately 100 suspected cases in humans are in a less degree than investigation by national health authorities in Thailand and Vietnam. The CDC World Health Organization, and national health authorities in Asian countries are working to assess and monitor the situation, provide epidemiologic and laboratory support, and assist with repress efforts.

Antigenic analysis and genetic sequencing distinguish between influenza viruses that usually circulate among birds and those that usually circulate among humans. Sequencing of the H5N1 viruses obtained from five human frames in Vietnam and Thailand, including single sister from the cluster in Vietnam, has indicated that all of the gene of these viruses are of avian origin. No evidence of genetic reassortment between avian and human influenza viruses has been identified. If re-assortment flash on the minds the likelihood that the H5N1 virus can be transmitted more readily from part to person will increase. Although all the gene are of avian origin, the present H5N1 viruses are antigenically distinguishable from those isolated from humans in Hong Kong in 1997 and 2003

Genetic sequencing of the five human H5N1 isolates from Thailand and Vietnam also indicates that the viruses have genetic characteristics associated with resistance to the influenza antiviral mix with drugss amantadine and rimantadine. Antiviral susceptibility testing confirms this finding. Testing for susceptibility of the H5N1 isolates to the neuraminidase inhibitor oseltamivir has demonstrated the sensitivity of these viruses to the drug; testing to determine susceptibility to the neuraminidase inhibitor zanamavir is in subordination to way.

The CDC attract favor tos that state and local health departments, hospitals, and physicians enhance their efforts to identify patients who could be infected through influenza A (H5N1) virus and take infection-control precautions when influenza A (H5N1) is suspected.

Testing of hospitalized patients for influenza A (H5N1) infection is indicated when the couple of the following exist: (1) radiographically confirmed pneumonia, acute respiratory distress syndrome or other rigid respiratory illness for which an alternative diagnosis has not been established, and (2) a history of travel within 10 days of symptom charge to a country where H5N1 avian influenza infections in domestic fowls or humans has been documented. Ongoing listings of countries affected from avian influenza are available from the World Organization for Animal Health (available online at http://www.oie.int/eng/en_index.htm).

Testing for influenza A (H5N1) also should be considered in succession a case-by-case basis in consultation with state and local health departments for hospitalized or ambulatory patients with all of the following conditions: (1) documented temperature higher than 38[degrees]C (1004[degrees]F); (2) cough sore throat, or shortness of breath; and (3) history of contact with domestic fowls or domestic birds (e.g., visited a domestic fowls farm, a household raising domestic fowls or a bird market) or a known or suspected patient with influenza A (H5N1) in an H5N1-affected rural parts within 10 days of symptom onset

The highly pathogenic avian influenza A (H5N1) virus requires Biosafety horizontal (BSL)-3+ laboratory conditions for certain performances The CDC recommends that virus isolation studies forward respiratory specimens from patients who fitting the testing criteria not be performed unles all BSL-3+ conditions are met However, clinical specimens can be proofed by polymerase chain reaction (PCR) assays by way of using standard BSL-2 work practices in a Class II biologic safety cabinet. The CDC has evolveed real-time PCR protocols (available to public health laboratories and online at http://www.aphl. org) for various respiratory pathogens, including cruel acute respiratory syndrome and influenza A and B viruses. In addition, commercially available antigen-detection ordeals can be used under BSL-2 flushs to test for influenza. Although these rapid standards for human influenza also can descry avian influenza A (H5N1) viruses, the sensitivity of these ordeals is substantially lower than that of virus cultivation or PCR.

Specimens from characters meeting clinical and epidemiologic indications for testing should be sent to the CDC if these somebodys test positive for influenza A either by means of PCR or antigendetection testing, or if PCR assays for influenza are not available locally. The CDC also will accept, for follow-up testing, specimens from human frames meeting the clinical and epidemiologic indications if it be not that testing negative on the rapid examples when PCR assay was not available. begs for testing by the CDC should arise through local and state health departments, which should contact the CDC's sudden [i]or[/i] unexpected occurrence Operations Center at 770-488-7100.