Testing for Swine Influenza (Updated Guidance May 1, 2009)
Due to the high volume of swine influenza test requests and limited testing supplies,
only specimens from patients meeting the following criteria are being accepted by University Hygienic Laboratory (UHL) for influenza PCR testing:
- Patients with an influenza-like illness (ILI*) who within 7 days of onset have traveled to or reside in a community either within the United States** or internationally where there are one or more confirmed swine influenza A (H1N1) cases, OR
- Patients admitted to the hospital with an ILI*.
*Influenza-like illness (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.
**As of 5/1/09, Iowa counties affected by A (H1N1) include Clinton, Des Moines, Johnson, Muscatine, and Marshall.
Providers are now required to submit both the UIHC Microbiology requisition and the UHL requisition (documenting the criteria in the patient history section) to the UIHC Microbiology Lab. The UHL requisition is available at: http://www.uhl.uiowa.edu/kitsquotesforms/vdvbpcrrequestform.pdf.
The UHL will reject specimens that do not have the section completed or do not meet the testing criteria. The specimen will be saved for 7 days waiting for more information.
Specimen Collection:
- Don personal protective equipment (N95 mask, gown, gloves, and eye protection) prior to specimen collection.
- Nasal wash: Instill several milliliters of sterile saline into nostrils while patient's head is tilted back. Bring patient's head forward and catch saline flowing from the nostrils in a sterile container. Pour specimen (1-2 ml) into transport tube containing viral transport medium (Hospital Stores #923740).
- Nasopharyngeal aspirate: A small catheter with a suction trap or bulb aspirator is inserted through the nostrils into the nasopharynx. Apply suction while slowly removing the catheter or aspirator tip. The catheter or aspirator tip should be flushed with viral transport medium (Hospital Stores #923740). Transfer entire specimen back into the transport tube.
- Nasopharyngeal swab: Collect specimen using the dacron-tipped wire swab from the Viral/Chlamydia Transport Kit (Hospital Stores #923740). Gently insert the swab through the nostril (parallel to the palate) into the nasopharynx until tip reaches distance equivalent to that from the ear to the nostril of the patient. Rotate swab several times, remove, and place swab in tube containing viral transport medium. Break off or cut the excess length of swab shaft to permit capping of the tube.
- For patients who are intubated, an endotracheal aspirate should also be collected.
Ordering Instructions:
- Two requisitions should be completed. Indicate "swine influenza" on the UIHC Microbiology requisition and the University Hygienic Lab (UHL) requisition. On the UHL requisition, clearly document relevant travel history and clinical information (see testing criteria, as noted above). If the patient has traveled to an affected area, write where and when the travel occurred.
- Routing specimens through the UIHC Microbiology Lab will ensure test results are entered in the electronic medical record.
Transport Instructions:
- Transport the specimen to the Microbiology Laboratory (6004 BT) immediately on ice or refrigerate. From 2245 to 0700, deliver specimen to Specimen Control (6240 RCP) on ice.
- Avoid using the tube system. If the tube system must be used, ensure specimens are in leak-proof containers that are securely closed and double bagged.
Laboratory Testing:
- The Microbiology laboratory will send the specimen to the University Hygienic Lab (UHL) for influenza PCR testing. Other influenza tests (rapid influenza antigen tests and immunofluorescence) have unknown sensitivity and specificity to detect swine influenza virus.
- The real-time RT-PCR at UHL detects influenza A, B, H1, and H3. Currently, swine influenza A (H1N1) virus will test positive for influenza A and negative for H1 and H3 by real-time RT-PCR. These strains will be sent to CDC for confirmation as swine influenza A.
Reminder:
- Please inform the Infection Prevention Program (pager 3158) that you are testing someone suspected to have swine influenza infection.
Questions:
- Questions regarding laboratory testing may be directed to Dr. Sandra Richter 6-2990 or Dr. Dan Diekema 4-5626.