OIE: Low pathogenic avian influenza (poultry), United States of America

Information received on 06/04/2009 from Dr John Clifford, Deputy Administrator, Animal and Plant Health Inspection Service, United States Department of Agriculture, Washington, United States of America

Summary

Report type Immediate notification
Start date 31/03/2009
Date of first confirmation of the event 31/03/2009
Report date 06/04/2009
Date submitted to OIE 06/04/2009
Reason for notification Reoccurrence of a listed disease
Date of previous occurrence 10/2008
Manifestation of disease Sub-clinical infection
Causal agent Low pathogenic avian influenza virus
Serotype H7N9
Nature of diagnosis Laboratory (advanced)
This event pertains to a defined zone within the country

New outbreaks

Summary of outbreaks Total outbreaks: 1
Outbreak Location and Affected population
  • KENTUCKY (Grayson County, Grayson County) : A commercial poultry broiler-breeder operation consisting of two poultry broiler-breeder houses with 20,000 birds that were 49 weeks old.
Total animals affected
Species Susceptible Cases Deaths Destroyed Slaughtered
Birds 20000 ** 0 20000 0
Outbreak statistics
Species Apparent morbidity rate Apparent mortality rate Apparent case fatality rate Proportion susceptible animals lost*
Birds ** 0.00% ** 100.00%

* Removed from the susceptible population through death, destruction and/or slaughter
** Not calculated because of missing information

Epidemiology

Source of the outbreak(s) or origin of infection
  • Unknown or inconclusive
Epidemiological comments ? 31 March 2009: a National Poultry Improvement Plan (NPIP) laboratory reported seropositive results for avian influenza. The birds were being tested as part of the NPIP Avian Influenza Clean Program (H5 and H7) for breeding facilities. No clinical signs other than a modest drop in egg production reported. No increase in mortality.
? 1 April 2009: Enhanced surveillance at the broiler-breeding operation implemented and additional laboratory samples were taken. There were no clinical indications of disease at the time of diagnostic testing.
? 2 April 2009: The National Veterinary Services Laboratory (NVSL) confirmed H7 RRT-PCR and hemagglutinin subtype as H7 positive.
--Laboratory testing is continuing, but to date no virus has been isolated.
? Kentucky State animal health officials, in coordination with USDA APHIS Veterinary Services, implemented the LPAI response plan in accordance with the Kentucky Initial State Response and Containment Plan for H5 and H7 LPAI. Implementation included:
- An enhanced surveillance zone of 10Km (6.2 miles) was implemented as outlined in the plan. There are four farms, all breeder facilities, and all owned by the same company, within the 10Km radius of the positive premises. Laboratory samples were collected and submitted from all four farms.
- Surveillance of backyard poultry flocks is being conduced within a 3Km (2-mile) radius of the premises.
? 4 April 2009: NVSL reported sera tested by haemagglutination inhibition test and neuraminidase inhibition test were seropositive for H7N9
? 4 April 2009: As a precautionary measure, all birds in the two houses were depopulated.
? 5 April 2009: All laboratory samples collected from the enhanced surveillance on the four breeding facilities yielded negative laboratory results for avian influenza.

Note by the OIE Animal Health Information Department: H5 and H7 avian influenza in its low pathogenic form in poultry is a notifiable disease as per Chapter 10.4. on avian influenza of the Terrestrial Animal Health Code (2008).

Control measures

Measures applied
  • Stamping out
  • Quarantine
  • Zoning
  • Vaccination prohibited
  • No treatment of affected animals
Measures to be applied
  • Disinfection of infected premises/establishment(s)

Diagnostic test results

Laboratory name and type National Poultry Improvement Plan (NPIP) laboratory (Local laboratory)
Tests and results
Species Test Test date Result
Birds agar-gel immunodiffusion (AGID) 31/03/2009 Positive
Laboratory name and type National Veterinary Services Laboratory (NVSL) (National laboratory)
Tests and results
Species Test Test date Result
Birds agar-gel immunodiffusion (AGID) 05/04/2009 Negative
Birds enzyme-linked immunosorbent assay (ELISA) 05/04/2009 Negative
Birds haemagglutination inhibition test (HIT) 04/04/2009 Positive
Birds neuraminidase inhibition assay 04/04/2009 Positive
Birds real-time reverse transcriptase/polymerase chain reaction (RRT-PCR) 02/04/2009 Positive
Birds real-time reverse transcriptase/polymerase chain reaction (RRT-PCR) 04/04/2009 Positive

Future Reporting

The event is continuing. Weekly follow-up reports will be submitted.