Diagnostic and Emerging Pathogen Strategies

By: Joseph F. Connor, DVM, MS Carthage Group

What do bovine and swine veterinarians have in common? When you compare Dr. Wade Taylor and I, you would dig deep to find anything. Any person that wants to fall off of a horse roping at a mature age is suspect to all types of questions! Swine veterinarians don’t have much risk falling off of a sow, but we do need to remember to duck a lot.

We have a common drive to understand pathogens, how they affect our species, how they emerge from common agents to pathogens, transmission rates, mitigation procedures, and treatment and prevention outcomes. With trade globalization and environmental shifting, we are concerned about emerging new agents or introduction of viruses and bacteria that are not currently present in our production systems. Host pathogen models are essential for designing strategies for managing disease threats to humans and domestic animals.

In 2013, porcine endemic diarrhea virus (PEDv) entered our swine populations. This virus diabolically altered our industry. I was fortunate enough to be consulted in these first cases. Clinical signs were similar to a well-known but infrequent virus in modern production (transmissible gastroenteritis, TGE). The virus causes diarrhea in all ages of pigs and mortality close to 100% in piglets less than 16 days of age in a naïve herd. Diagnostic laboratories were not routinely conducting tests for PEDv and laboratory tests were negative to TGE. The original cases of identified clinical cases occurred in Colorado and Indiana at almost the same time with no connection between those populations. Retrospectively, we know that 1-2 months prior, the virus was present but not confirmed. Subsequently PEDv spread through our industry in the fall and winter of 2014-2015.

The sudden emergence of this virus generated lots of progression in our industry and has redefined our learning, preparedness, clinical management, and introduction risks. These are lessons learned:

1) Agents that may affect tread are classified as FAD (Foreign Animal Disease) or transboundary (PEDv).

2) Transboundary classification may be good but also clouds who is in charge of some key decision processes and the speed of the decisions.

3) Diagnostic laboratories need to be prepared and routinely conducting analysis on agents of concern.

4) The industry needs to allow routine surveillance for agents of concern.

5) We need to look at other methods of introduction, i.e., ingredient contamination.

6) Once an agent enters a population with the daily movement of pigs, it is challenging if not impossible to prevent widespread movement through geographies.

7) Historically low value risks may be high risks, i.e., collection areas for pigs including market hog lairages and cull sow stations.

8) Contaminated transport trailers continue to be a convenient method of transmission in any fecal/oral agent.

9) Aerosol transmission occurs short distances even with primary fecal/oral route.

10) Veterinarians can adjust management interventions to minimize the losses and eliminate the virus from individual populations.

The most important outcome was to change the way we approach the global understanding of risks. We formed SHIC (Swine Health and Information Center). The mission of SHIC is to protect and enhance the health of the United States swine herd through coordinated global disease monitoring, targeted research investments that minimize the impact of future disease threats, and analysis of swine health data. This center is funded through our Pork Checkoff and has evolved quickly to include these facets:

1) Swine health monitoring project,

2) Emerging disease monitoring data,

3) PADRAP – Production Animal Disease Risk Assessment Program,

4) Rapid response team,

5) Secure pork supply,

6) Trade support, and

7) Agent fact sheets.

The board and committees meet regularly to assess information that might suggest any emerging pathogen both domestically and globally. Importantly, the board commissioned practical research to evaluate the agent survival ability of agents from high risk areas to US and from this is driving research on mitigation interventions. How does this tie us together? The highest economical pathogens are Foreign Animal Disease (FMD and Vesicular Viruses) that affect multiple species. Dr. Wade, PAC, and we are linked in supporting protein sustainability.

Paddy had shingles.