Highly pathogenic avian influenza,
United States of America
Information received on 09/04/2020 from Dr Mark Davidson, Associate Administrator, USDA-APHIS, United States Department of Agriculture, Washington, United States of America
Report type Immediate notification
Date of start of the event 06/04/2020
Date of confirmation of the event 08/04/2020
Report date 09/04/2020
Date submitted to OIE 09/04/2020
Date event resolved 28/05/2020
Reason for notification Recurrence of a listed disease
Date of previous occurrence 11/08/2017
Manifestation of disease Clinical disease
Causal agent High pathogenic avian influenza
Serotype H7N3
Nature of diagnosis Laboratory (advanced)
This event pertains to a defined zone within the country
Related reports Immediate notification (09/04/2020)
Follow-up report No. 1 (16/04/2020)
Follow-up report No. 2 (24/04/2020)
Follow-up report No. 3 (30/04/2020)
Follow-up report No. 4 (07/05/2020)
Follow-up report No. 5 (15/05/2020)
Follow-up report No. 6 (21/05/2020)
Follow-up report No. 7 (05/06/2020)
Follow-up report No. 8 (05/08/2020)
New outbreaks (1)
Outbreak 1 Chesterfield County, Chesterfield, South Carolina
Date of start of the outbreak 06/04/2020
Outbreak status Resolved (28/05/2020)
Epidemiological unit Farm
Affected animals
Species Susceptible Cases Deaths Killed and disposed of Slaughtered
Birds 34160 1583 32577 0
Affected population Commercial meat-type turkey flock
Summary of outbreaks Total outbreaks: 1
Total animals affected
Species Susceptible Cases Deaths Killed and disposed of Slaughtered
Birds 34160 ** 1583 32577 0
Outbreak statistics
Species Apparent morbidity rate Apparent mortality rate Apparent case fatality rate Proportion susceptible animals lost*
Birds ** 4.63% ** 100.00%
*Removed from the susceptible population through death, destruction and/or slaughter
**Not calculated because of missing information
Source of the outbreak(s) or origin of infection
  • Unknown or inconclusive
Epidemiological comments 23 Apr 2020 Update--All control area and enhanced surveillance testing have reported negative results since 8 Apr 2020. The USDA Animal Plant Health Inspection Service (APHIS) and South Carolina State Veterinarianís Office, part of Clemson University Livestock Poultry Health (CULPH), continue conducting a comprehensive epidemiological investigation and enhanced surveillance, including targeted network surveillance, in the area. Based on sequencing information for all H7N3 NC/SC cases, data supports a single introduction of the virus followed by secondary spread. Mutation of the LPAI virus to HPAI occurred in one house on a single premises. Sequencing information also supports that H7N3 LPAI NC/SC viruses are: 1. distinct from other recent H7 events in poultry, and have not previously been detected in poultry 2. similar to other wild bird viruses, sharing a common HA ancestry with those from 2016-2018 3. North American wild bird-origin viruses 4. NOT related to the H7N3 HPAI event in Mexico nor the Anhui lineage H7N9 viruses
Control measures
Measures applied
  • Zoning
  • Stamping out
  • Official disposal of carcasses, by-products and waste
  • Quarantine
  • Surveillance within containment and/or protection zone
  • Surveillance outside containment and/or protection zone
  • Movement control inside the country
  • Vaccination prohibited
  • No treatment of affected animals
Measures to be applied
  • Disinfection
Future Reporting
The event is continuing. Weekly follow-up reports will be submitted.
Map of outbreak locations