Influenza A Virus Infection, Novel Subtypes

Wisconsin Division of Public Health Disease Surveillance Manual (EpiNet, February 2008)

I.     IDENTIFICATION

A.    CLINICAL DESCRIPTION:  An illness compatible with influenza virus infection.

B.    REPORTING CRITERIA:  Laboratory confirmation.

C.    LABORATORY CRITERIA FOR CONFIRMATION:  A human case of infection with an influenza A virus subtype that is different from currently circulating human influenza H1 and H3 viruses. Novel subtypes will be detected with methods available for detection of currently circulating human influenza viruses at state public health laboratories (e.g., real-time reverse transcriptase polymerase chain reaction [RT-PCR] or through virus isolation).  Laboratory tests to confirm whether an influenza A virus represents a novel virus will be conducted by CDC’s influenza laboratory.  Novel subtypes include, but are not limited to:

• H2, H5, H7, and H9 subtypes.
• Influenza H1 and H3 subtypes originating from a non-human species or from genetic reassortment between animal and human viruses are also novel subtypes.

D.    CASE CLASSIFICATION:
Confirmed: A case of human infection with a novel influenza A virus confirmed by CDC's influenza laboratory.

Probable: A case meeting the clinical criteria and epidemiologically linked to a confirmed case, but for which no laboratory testing for influenza virus infection has been performed.

Suspected: A case meeting the clinical criteria, pending laboratory confirmation. Any case of human infection with an influenza A virus that is different from currently circulating human influenza H1 and H3 viruses is classified as a suspected case until the confirmation process is complete.
       
II.    ACTIONS REQUIRED / PREVENTION MEASURES

A.    WISCONSIN DISEASE SURVEILLANCE CATEGORY II: Report to the patient's local health officer on an Acute and Communicable Disease Case Report (DPH 4151) or other means within 72 hours of the identification of a case or suspected case.

B.    EPIDEMIOLOGY REPORTS REQUESTED: 

• Acute and Communicable Diseases Case Report (DPH 4151).
• Novel Human Influenza A Case Report Form (Contact CDES at phone numbers below)

C.    PUBLIC HEALTH INTERVENTIONS: 

• Case investigation by LHD to include history of travel, dates, mode of transportation, and case management
• Determine if case is outbreak-related and notify DPH Regional Office or CDES.

III.  CONTACTS FOR CONSULTATION

A.    DPH REGIONAL STAFF: See Epinet Introduction: “REGIONAL OFFICE CONTACTS”.

B.    BCD / COMMUNICABLE DISEASE EPIDEMIOLOGY SECTION: (608) 266-5326 or (608) 267-7321.

C.    WSLH / VIRUS ISOLATION: (608) 262-3185.

IV.  RELATED REFERENCES

1.     Heymann DL, ed. Influenza. In: Control of Communicable Diseases Manual. 18th ed. Washington, DC: American Public Health Association, 2004:281-287

2.     Pickering LK, ed. Influenza. In: Red Book: 2006 Report of the Committee on Infectious Diseases. 27th ed. Elk Grove Village, IL: American Academy of Pediatrics, 2006:401-411.