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Network of expertise on animal influenza

OIE - World Organization for Animal HealthFAO - Food and Agriculture Organization of the United Nations

Collection of Specimens for Detection of Influenza from Swine

16 June 2009

Compiled by Mia Kim (FAO) and Jan Pedersen (USDA‐APHIS) from the following contributors: 
Drs. Amy Vincent (USDA‐ARS), Sabrina Swenson (USDA‐APHIS),
Gaëlle Kuntz‐Simon and Nicolas Rose (French Agency for Food Safety [AFSSA])


Recommended specimens for detection of influenza virus from swine:

  1. Nasal swab
  2. Lung tissue

1. Nasal swab

DO NOT pool swabs from individual pigs.

Use sterile dacron tip swab with plastic shaft at least 6 inch/15 cm in length.
A. The pig should be properly restrained with the head positioned upward to allow easy access to the nasal cavity. Anesthesia is not needed. 
B. Insert a sterile Dacron swab into the nasal cavity in a dorsal‐medial direction and gently swab the surface of the nasal mucosa using a circular motion to cover as much of the nasal mucosal surface as possible. The swab will collect nasal mucosal secretions and surface epithelium.

  • Avoid touching the skin with the swab as you enter the nasal cavity
  • It is important not to scrape too hard, as drawing blood is undesirable
  • Using the same swab, remove the Dacron swab from one nostril and repeat the same procedure in the other nostril
  • Approximate depth to insert swabs for optimal sample:
    • 1 cm for piglets 0 to 4 weeks‐old
    • 2 cm for nursery pigs from 4 to 7 weeks‐old
    • 3 to 4 cm for fattening pigs > 7 weeks of age

C. Once the nasal swab has been collected, vigorously mix the swab in a transportmedia designed for maintaining viruses (viral transport media or PBS).

D. The volume of viral transport media should be sufficient to cover the head of theswab.

E. To remove the swab handle, back the swab out of the tube slightly and bend thehandle back and forth over the edge of the tube until it breaks.  Alternatively,scissors or wire cutters can be used to cut the swab handle.

F. The swab handle should be short enough to allow the tube to close tightly andlong enough to allow for easy retrieval once the tube reaches the laboratory.

G. Clearly label with appropriate identification and immediately refrigerate or chill.

  • It is important for the specimen to remain cold (approximately 4C) from thecollection to the shipping process.  A constant cold chain should be maintained.

H. Store on wet ice (at approximately 4C) and ship refrigerated in an upright positionto reduce chances of leakage.

I. Do not pool swabs from more than one pig into a single tube.

2. Lung Tissue:

A. Collect multiple sections of lung tissue from affected areas. Fresh lung tissue should be collected as autolysis will cause the production of enzymes which can inactivate virus or be inhibitory to PCR.     

B. Samples should be at least half‐dollar size or approximately 3‐4 grams.  

C. Include the junction of normal and abnormal lung tissue.    

D. Double bag and clearly label with appropriate ID and refrigerate or chill immediately.  For preservation of the specimen it is necessary to maintain a cold chain from the point of collection through shipping and receipt of the testing laboratory.  

E. Do not pool tissues from more than one pig in a bag. Lung tissue from each individual animal should packaged separately.



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