USDA Develops, Implements Influenza Surveillance Plan

September 16, 2009 — 

USDA's Veterinary Services (VS) has developed and implemented a voluntary surveillance plan for swine influenza virus (SIV), including the pandemic H1N1 2009 virus1 (pH1N1), in swine.

The immediate goals of the surveillance program are to:

1. Determine if the pH1N1 virus strain currently exists in U.S. swine;
2. If the pH1N1 strain is present, determine the distribution to inform further policy decisions;
3. Detect other novel influenza virus strains in swine in a timely manner; and
4. Determine genetic characteristics of novel viruses necessary for vaccine and diagnostics development.

Reports from officials in countries where swine have become infected with pH1N1 virus and researchers conducted at the USDA's Agricultural Research Service (ARS) indicate that infection in pigs closely resembles seasonal flu exposure. Pigs exhibit fevers, anorexia, ocular/nasal discharge, barking cough and lethargy followed by complete recovery with low mortality and high morbidity.

The surveillance program focuses on three sources of samples:

1. Swine populations epidemiologically linked to a human case
2. Case-compatible swine accessions submitted to veterinary diagnostic labs
3. Sick pigs at first points of concentration or commingling events.

These samples will be submitted to a National Animal Health Laboratory Network (NAHLN) lab to characterize isolates for further analysis.

Slaughter sampling is not a part of the surveillance program. Pigs exhibiting influenza-like illness are not shipped to slaughter facilities until recovered and the same standard operating procedures will be followed with pigs exposed to pH1N1. Sick pigs at the slaughter facility should be handled according to USDA Food Safety and Inspection Service standard protocols and procedures.

This surveillance program will target all influenza viruses in pigs including pH1N1 with the objectives of:

• Detecting changes in the swine influenza virus genome and sharing isolates with the Centers for Disease Control and Prevention (CDC).
• Providing geographical and temporal data related to novel genomic sequences of interest to animal and public health officials.

Projected outcomes include:

• Knowledge of the presence and distribution of novel influenza viruses
• Establishing a baseline for novel SIV genomics
• Aggregating and sharing SIV isolate information
• Building "One Health" protocols and system capacity for emerging zoonotic SIV viruses as well as other possible emerging pathogens
• Facilitating further research and understanding of the ecology and epidemiology of SIV infection in swine
• Developing a better understanding of epidemiological factors and procedures that either limit or enhance the mutation and spread of SIV in the swine population.

Additional information can be viewed at http://nsu.aphis.usda.gov/outlook/issue22_jul09/siv_surveillance.pdf on the USDA-APHIS website.