Laboratory Diagnosis

Sample Collection

All specimens sent to the laboratory for testing should come with a history of the clinical and gross lesions observed. Multiple specimens from the same farm should be sent because tests on a single specimen may fail to yield the virus. Samples need to be kept frozen during shipping.

Dead birds:

Lungs
Air sacs
Trachea
Brain
Pancreas
Spleen
Serum (ducks and geese)

Live birds:

Tracheal and cloacal swabs or feces
- Swabs should be transferred to brain and heart infusion broth or other cell culture maintenance medium containing high levels of antibiotics.
- Cloacal swabs from up to five birds can be pooled in the same tube of broth
Clotted blood or serum from several birds

Identification of the Agent

The agent is identified by inoculating 9- to 11-day-old embryonated chicken eggs with swabs or tissue specimens, followed by:

Demonstration of hemagglutination
Immunodiffusion test to confirm the presence of avian influenza A virus
Subtype determination with monospecific antisera

Strain virulence can be assessed by evaluation of the intravenous pathogenicity index (IVPI) in 4- to 8-week-old chickens.

Serologic Tests

Because sera from infected chickens can yield positive antibody tests as early as 3 to 4 days after the first signs of disease appear, serologic tests can be useful to diagnose the disease (see References : Beard 1998).

Specific hemagglutination inhibition tests are the basis for determining the antibodies associated with the influenza viral strain
Agar gel immunodiffusion
Commercial enzyme-linked immunosorbent assay (ELISA) test kits
- All positive readings are confirmed with agar gel precipitation tes

Free Ask Question:

1. Definition of Avian Influenza?

2. Agent?

3. Hosts?

4. Transmission?

5. Key Outbreaks of HPAI in Domestic Avian Populations?

6. Current Status of H5N1 in Asia?

7. HPAI As a Biological Weapon?

8. Clinical Features?

9. Differential Diagnosis?

10. Laboratory Diagnosis?

11. Treatment?

12. Prevention?

13. Outbreak Control in Poultr?