Advocacy in action – Swine influenza surveillance (Nov 2010)

Harry Snelson, DVM

As you read this, we are entering the traditional influenza season. Swine influenza is nothing unusual for swine veterinarians. We’ve all observed the characteristic clinical signs, including coughing, sneezing, fever, anorexia, lethargy, and nasal-ocular discharge. It’s surprising, then, how little information we actually have on the prevalence, epidemiology, and distribution of this disease within the US swine industry.

For many years, the AASV has worked with the National Pork Board and United States Department of Agriculture (USDA) to consider the development of a comprehensive swine disease surveillance program to replace the current practice of surveillance based on programmatic disease. Swine influenza virus (SIV) surveillance would be but one component of the much broader comprehensive program. This process received some additional emphasis in 2008 when the Centers for Disease Control and Prevention (CDC) provided funding to institute a surveillance program that would allow public-health researchers access to SIV isolates to evaluate for possible zoonotic potential. Also in 2008, USDA announced VS 2015 – a strategic vision designed to overhaul the organization to better meet animal-health needs in the 21st century. A key component of VS 2015 is the move toward more comprehensive animal disease surveillance. Then, in April 2009, the pandemic H1N1 virus arose and additional resources became available to fund influenza surveillance in the swine industry.

The Comprehensive and Integrated Swine Surveillance program would enable monitoring of zoonotic, endemic, emerging, and foreign-animal diseases. The cornerstone of a comprehensive program is identifying points throughout the pork-production continuum where diagnostic samples could be routinely collected and submitted to the veterinary diagnostic laboratory system. Once the samples are collected, diagnostic testing could be varied, depending on the pathogens of interest to the various stakeholders.

The proposed program is an improvement over the current system, which conducts surveillance efforts that are based on individual program diseases. Today’s surveillance model requires implementation of a new surveillance system for each program disease and separate funding to support each surveillance effort. The goal of a comprehensive surveillance system is to design a routine sample-collection strategy that would allow for flexibility in testing and would promote a consistent funding stream.

The stakeholder groups have continued to work with the government agencies to hammer out a plan that would allow for implementation of an SIV surveillance program as the first step towards realizing a comprehensive surveillance program. The SIV surveillance program would facilitate access to virus isolates of interest to animal- and public-health authorities, while ensuring that producers and veterinarians are not compromised in the process. Planning for implementation of the SIV surveillance program is nearing completion, and it is being tested at this time. Hopefully, by the time this article appears, the program will be up and running and accepting submissions. That’s where you come in.

The success of this effort relies on the participation of veterinarians and producers. Swine influenza in animals is not a reportable disease. Therefore, participation in a surveillance program is voluntary. Every effort has been made to ensure the anonymity of all information collected as a result of the routine surveillance program. It is important that veterinarians and producers are comfortable with the collection and submission process and understand that no additional action will be taken on the part of USDA or CDC in response to the findings of the surveillance program.

So, you may be asking, “Why should I participate in an SIV surveillance program?” The objectives of the surveillance program are as follows:

• Monitor the genetic evolution of SIV to better understand endemic and emerging influenza virus ecology;
• Make available SIV isolates for research and establish an objective database for genetic analysis of these isolates and related information; and
• Select proper isolates for development of relevant diagnostic reagents, updating diagnostic assays, and vaccine seed-stock products.

One of the key benefits to producers is a better understanding of the influenza strains routinely circulating in the US swine herd and an early recognition of any newly emerging strains. The lack of this information became apparent following the emergence of the pandemic H1N1 strain in April 2009. As an industry, we had limited information regarding whether or not the strain was currently, or had ever been, circulating in the swine population. There were no readily available diagnostics or seed-stock viruses for vaccine development. We had to start from scratch to answer consumer questions and develop the needed technologies to effectively respond.

In addition, there was no formalized method to share virus isolates between researchers within animal and human health. The CDC is interested in accessing influenza viruses circulating in the animal population to facilitate surveillance for viruses that may have zoonotic potential. This surveillance program facilitates that interaction. Working with our public-health partners fosters a better understanding of the impact these findings can have on the animal-agriculture industry. Having an effective, meaningful surveillance program is important to promote and retain access to export markets as well. It is difficult to reinforce our disease status to trading partners without an effective surveillance program.

Influenza samples are eligible for inclusion in the surveillance program if they meet at least one of three criteria:

• The samples are submitted to a veterinary diagnostic lab from clinically ill pigs.
• The samples are collected at points of concentration or commingling, such as fairs, exhibitions, markets, and auctions, from swine exhibiting influenza-like illness.
• The samples are collected from swine epidemiologically linked to a confirmed isolation of SIV in a case of human infection.

All samples submitted to the influenza surveillance program will be anonymous unless the producer specifically requests in writing inclusion in a traceable database, or the samples are collected as a result of an epidemiologic association with a human infection. The only information contained within the anonymous surveillance database would be an anonymous bar code, the date the sample was collected, the state in which the sample was collected, age of swine sampled, reason for collection or clinical signs, and all SIV testing results.

If the virus is sequenced, the sequence will be submitted to GenBank. The USDA’s National Veterinary Services Laboratory will retain an aliquot of the sample for access by animal-health and public-health researchers. All diagnostic information requested by the practitioner will be reported by the veterinary diagnostic laboratory as usual for any diagnostic sample submission. The costs for additional testing are covered by USDA, thus, participation in the surveillance program will not result in any additional cost to the producer.

It is hoped that development of the SIV surveillance program will lay the groundwork for its expansion into a comprehensive and integrated swine surveillance program. Success of the program and access to continued funding requires active participation on the part of swine veterinarians and producers. A consistent stream of samples truly representative of the swine industry is critical, and we encourage you to work with your clients to continue to do what you’ve always done – submit samples to the diagnostic laboratory.

–Harry Snelson, DVM