Interim Guidance for Screening for Novel Influenza A (H1N1) (Swine Flu) by State and Local Health Departments, Hospitals, and Clinicians in Regions with Few or no Reported Cases of Novel Influenza A (H1N1)

May 1, 2009 11:15 PM ET

This document provides interim guidance for state and local health departments, hospitals, and clinicians participating in surveillance activities in regions with few or no reported cases of novel influenza A (H1N1) (swine flu) virus infection regarding which patients to evaluate for possible infection with novel influenza A (H1N1) virus. Confirmed cases of novel influenza A (H1N1) virus infection have been identified in multiple states and countries. Based on the rapid spread of novel influenza A (H1N1) virus thus far, public health officials believe that more cases will be identified over the next several weeks, including in regions that currently have few or no reported cases.

CDC recommends that state and local health departments, hospitals, and clinicians in regions with few or no reported cases of novel influenza A (H1N1) virus infection consider the following recommendations for testing of the following persons for novel influenza A (H1N1) virus infection with a nasopharyngeal swab by PCR:

1. Patients presenting to providers participating in the US Outpatient Influenza-like Illness Surveillance Network (ILINet) who meet the case definition of influenza-like illness (ILI), or
2. Patients admitted to the hospital with an ILI.

ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and a cough and/or a sore throat in the absence of a KNOWN cause other than influenza.

Specimen Collection and Testing

If swine flu is suspected, clinicians should obtain a respiratory swab for novel influenza A (H1N1) virus testing and place it in a refrigerator (not a freezer). Once collected, the clinician should contact their state or local health department to facilitate transport and timely diagnosis at a state public health laboratory. State public health laboratories should perform subtype testing on all influenza A positive samples identified. Specimens that cannot be subtyped as human influenza A (H1N1) or (H3N2) should receive additional testing for detection of the novel influenza A (H1N1) virus if available or sent to CDC for identification. Please notify CDC of all pending shipments by email at eocsciresource@cdc.gov or if email is not available, by phone at 404-553-7724. Please include shipment tracking information.

These guidelines are not intended to restrict testing to persons meeting screening criteria, and additional clinical or epidemiologic information should be used in determining whether persons who do not meet these screening criteria should receive additional evaluation for possible novel influenza A (H1N1) virus infection.

Also see interim guidances available at http://www.cdc.gov/swineflu including:

• Case definitions to be used for novel influenza A (H1N1) virus infection cases
• Antiviral recommendations for patients with confirmed or suspected novel influenza A (H1N1) virus infection and close contacts
• Infection control for care of persons with confirmed or suspected novel influenza A (H1N1) virus infection in a healthcare setting
• Novel influenza A (H1N1) virus biosafety guidelines for laboratory workers
• Specimen collection, processing, and testing