Screening for H1N1 Influenza A

Screening for H1N1 Influenza A (Swine Flu) in Regions With Few or No Cases: Guidance for Clinicians
Deborah Brauser
From Medscape Infectious Diseases Published: 05/05/2009

Their interim screening guidelines for areas with few or no reported cases include how to determine which patients should be specifically evaluated for possible infection, how to test, and important steps to take afterwards.

What Is an Influenza-like Illness?
The CDC defines influenza-like illness (ILI) as one that includes fever with a temperature of 100° F (37.8° C) or greater, accompanied by cough and/or sore throat, in the absence of a known cause other than influenza.

Which Patients With ILI Should Be Tested?
For clinicians in areas that currently have very low numbers of S-OIV outbreaks or none at all, the CDC recommends testing for infection in the following:

1.Patients who meet the case definition of ILI and present to providers who participate in the US Outpatient Influenza-like Illness Surveillance Network (ILINet; an organization of approximately 2400 healthcare providers in 50 states who provide weekly reports to the CDC of patient visits for ILI as a way to regularly track influenza)
2.Patients with an ILI who have traveled within 7 days to an area either within the United States or internationally with 1 or more confirmed swine influenza A (H1N1) cases (To find the most up-to-date information on these areas, see http://www.cdc.gov/swineflu/index.htm)
3.Patients admitted to the hospital with an ILI
These patients should be segregated promptly as they await assessment, and all healthcare personnel interacting with them should follow infection-control guidelines as shown at http://www.cdc.gov/h1n1flu/guidelines_infection_control.htm

How Should Tests Be Administered?
In patients who meet the criteria listed above, clinicians should obtain an upper respiratory specimen to test for the influenza A (H1N1) virus. This means:

Collecting a nasopharyngeal swab/aspirate or nasal wash/aspirate
If these specimens cannot be collected, a combined nasal/oropharyngeal swab is acceptable
For patients who are intubated, an endotracheal aspirate should also be collected

Clinicians should pay special attention to the type of swab used, keeping the following in mind:
Ideally, specimens should be collected using swabs with a synthetic tip and an aluminum or plastic shaft
Swabs with cotton tips and wooden shafts are not recommended
Specimens collected with swabs made of calcium alginate are not acceptable

The specimens should then be placed in a sterile refrigerator (not a freezer), and clinicians should immediately contact their state or local health department to find out the quickest way to submit and transport the sample to a state public health laboratory.

These labs will then perform subtype testing on all influenza A (H1N1)-positive samples identified; specimens that cannot be subtyped as human influenza A (H1N1) or (H3N2) will be sent to CDC for identification.

What Precautions Should Be Taken by Healthcare Workers?
To prevent the transmission of all respiratory infections in healthcare settings, respiratory hygiene/cough etiquette infection-control measures (located at http://www.cdc.gov/flu/professionals/infectioncontrol/resphygiene.htm) should be implemented at the first point of contact with a potentially infected person.

In addition, all healthcare personnel:
1.Who work in areas where there are patients being assessed or isolated for H1N1 (including those in an outpatient setting or emergency department) should be monitored daily for signs and symptoms of febrile respiratory infection
2.Who develop symptoms should be instructed not to report to work; if they are already at work, they should cease patient-care activities and notify their supervisor and infection-control personnel
3.Who are asymptomatic but have had an unprotected exposure to H1N1 may continue to work if they are started on antiviral prophylaxis

Interim guidance on antiviral recommendations for those who have had close contact with patients who have confirmed or suspected swine influenza A (H1N1) virus infection can be found at http://www.cdc.gov/h1n1flu/recommendations.htm

Where Can I Find the Latest Information?
The CDC Website offers additional guidance recommendations, case definitions, and more on screening at http://www.cdc.gov/h1n1flu/screening.htm
The World Health Organization is coordinating a global response to human cases of influenza A (H1N1), monitoring the current outbreaks and providing access to technical guidelines and useful information; see http://www.who.int/csr/disease/swineflu/en/index.html
Information is updated throughout the day at http://www.medscape.com/sites/swine-flu