Influenza in Swine

Veterinary Resources:

USDA's Influenza in Swine Surveillance Program -- USDA's National Surveillance Unit has developed a routine surveillance program for the detection and identification of influenza viruses in the U.S. swine herd. The objective of the surveillance plan is to identify circulating influenza strains in swine, sequence these strains and make those sequences available to animal and public health researchers for further analysis. Updated: 10/2010.

Influenza Sample Collection and Submission Protocol -- Dr. Kent Schwartz has provided these guidelines from the ISU VDL for collecting and transporting SIV diagnostic samples. Additional information on sample submissions to the ISU VDL can be found on their website at

2009 Pandemic H1N1 Information

AASV Pandemic H1N1 Position Statements -- AASV position statements regarding issues associated with the novel H1N1 2009 Pandemic Influenza Virus.

Actions for Suspected or Confirmed Novel H1N1 in Pigs -- This document summarizes the actions to be taken by state and federal animal health officials following the discovery of a suspected or confirmed case of H1N1 Pandemic Influenza virus in the U.S. swine herd. Updated: 09/02/2009

Presumed and Confirmed pH1N1 Viruses in Animals -- Spreadsheet maintained by USDA listing all suspect and confirmed pH1N1 diagnostic test results submitted to NVSL.

2009 Cases

2010 Cases

Veterinary Talking Points -- Basic talking points regarding the human H1N1 influenza outbreak. Updated: 05/29/09

Key Points for Veterinarians -- Information targeting veterinarians. Last updated: 1:30pm EDT, 4/26/09


Research Updates:

Four Pig Pathogenesis Study with the 2009 A/H1N1 Influenza A Virus -- ARS research conducted at the National Animal Disease Center (NADC) to investigate whether meat, blood and tissue from pigs infected with the new 2009 H1N1 Influenza A Virus is free of infectious virus. CONCLUSION: Live 2009 A/H1N1 Influenza A Virus was only detected in the respiratory tract of infected pigs and the virus does not appear to spread and replicate in other tissues based on the day 5 post infection samples.

Serologic Cross-reactivity of US Pig Serum against Novel H1N1 Influenza Virus -- ARS research to evaluate whether US commercial swine herds are susceptible to the new swine origin (S/O) H1N1 influenza virus. CONCLUSION: Pre-existing immunity induced by swine influenza viruses circulating in the US may not protect pigs against the new S/O H1N1 influenza virus presently circulating in people. Importantly, vaccines currently used to protect pigs in US swine operations against swine influenza virus may not be effective against the new S/O H1N1 influenza virus.

Pig Transmissibility and Pathogenecity Study -- Preliminary results of studies conducted in the EU to investigate the pathogenicity and transmissibility of the novel influenza A/H1N1-2009 virus in pigs. Preliminary analyses: Summary Conclusions -- Pigs are susceptible to infection with influenza A (H1N1) virus that results in the induction of detectable levels of clinical disease, virus shedding and pathology in an experimental setting. Importantly, mortality was not a feature and infected animals were able to transmit the virus to naïve contact pigs successively for at least three cycles of transmission, suggesting the virus could become established in susceptible pig populations if introduced.

Producers Resources:

Swine Exhibition and Show Recommendations -- Published by the Show Pig Working Group. Last updated: 5/18/09

Recommendations for producers -- Published by the National Pork Board. Last updated: 5:30pm EDT, 4/24/09

Influenza Fact Sheet -- Fact sheet produced by the National Pork Board. Good background information on influenza viruses in swine.

Miscellaneous Links:

ARS 2009 H1N1 Influenza A Virus -- USDA ARS 2009 H1N1 homepage.

USDA H1N1 Information -- USDA H1N1 website. Provides official information on the 2009 H1N1 Influenza outbreak from the Department of Agriculture.

CDC Recommendations for Swine Workers -- Recommendations from the Center for Disease Control and Prevention (CDC) targeting swine farm workers designed to minimize transmission of pH1N1 influenza virus from people to pigs and vice versa. Posted November 3, 2009.

CDC Influenza Investigation -- Official update from the Center for Disease Control and Prevention (CDC)

USDA Influenza Statement -- Statement from Secretary of Agriculture Vilsack. 4/26/09

Dr.Clifford's Request for Swine Case Reports -- Dr. John Clifford, USDA Chief Veterinarian, has requested state veterinarians and AVICs provide USDA with reports on any past or on-going cases of swine influenza.