Flu Update & Sample Submission Guidelines

April 27, 2009 — 

Following is the latest update on the H1N1 influenza outbreak:

• As of the 1:00pm EDT update, CDC is confirming 40 cases in 5 states (CA, TX, KS, OH & NY). None have any reported direct contact with swine. The outbreak continues to be transmitted human to human.
• According to the World Health Organization (WHO), the virus has been confirmed in 4 countries -- Mexico, U.S., Canada and Spain.
• The World Organization for Animal Health (OIE) is recommending that a more appropriate name for the virus would be "North-American influenza" since there has been no evidence of animal involvement.
• NVSL & NADC have received the virus isolated from cases in California and are beginning work to investigate questions associated with:
  • diagnostic testing,
  • swine susceptibility, transmission and pathogenesis,
  • vaccine efficacy,
  • etc.
  They have already determined that the current matrix test available in the National Animal Health Lab Network (NAHLN) labs will detect this virus, but a differential test is still being developed. Serology will be of limited value since the HA component of this virus is common in normal circulating SIV.
• 5 countries (Russia, China, Philippines, Serbia & Kazakhstan) have announced bans on some pork imports from the U.S. and Mexico while the WHO confirms that pork is safe to eat.
• Market hog prices were down the limit today.

Samples for the Diagnosis of Swine Influenza

Dr. Kent Schwartz has provided the following guidelines for the collection, handling and shipping of samples for SIV diagnosis at the Iowa State University Veterinary Diagnostic Lab. Additional information is available on the ISU-VDPAM website.

Pig selection: High fever, serous nasal discharge

Nasal swabs: Dacron or other synthetic fiber swabs in transport media (e.g. BBL CultureSwab with Stuarts media) or in 1 ml saline in snap cap tubes; cluster in whirlpaks

Lung lavage fluid: Saline in leak-proof sterile containers (snap caps, blood tubes, whirlpaks)

Airway brush swabs: Swab larger bronchioles after cutting into lung lobes. (e.g. Copan flocked nylon fiber swab with accompanying screwtop vial containing sterile media); cluster in whirlpaks

Fresh lung tissue: Affected portions of lung tissue, usually the hilar area and adjacent portions of cranial, middle and caudal lung lobes or ventral portions of these lobes; in whirlpaks, chilled not frozen, on icepaks or wet ice

Formalin-fixed lung tissue: Slices (1/2") through affected portions of lung in 10% buffered formalin

Follow routine diagnostic sample packaging guidelines: Double bag specimens or line shipping container with plastic bag, preferably in styrofoam-lined container with coolant packs.

The samples described above would also be useful for diagnosis or any acute respiratory disease in swine.

Diagnostic assays that can be applied to these samples:
PCR assay for Type A and subtypes H1, H3, N1, N2
Sequence determination for the HA genes
Virus isolation

Note: PCR assays currently employed at ISU VDL will detect both the H1 and N1 of the influenza A H1N1 virus currently of concern in human infections. Work is in progress to develop assays that will differentiate the virus from other H1N1 viruses currently infecting swine.

[Editor's note: We are continuing to update information on the AASV homepage as needed.]