Active Participatory Surveillance for Early Detection of Notifiable Pathogens: A Case Study of the U.S. Swine Industry.

The continued global spread of WOAH-listed pathogens via trade, transport, and travel calls for the implementation of biosecurity measures to protect the health of our national livestock industries, plus ongoing surveillance to verify that such measures are operative. Despite this urgency, surveillance must be practical and affordable. Herein, we evaluated the performance and cost of participatory surveillance, a nontraditional surveillance design, using the U.S. swine industry as an example. In this context, "participatory" meant that herd veterinarians and/or producers collected and submitted samples from the herd to accredited laboratories for testing. To create an infected population (Phase 1), we simulated the introduction and spread of an unspecified notifiable pathogen within the 48 contiguous U.S states (66,637 swine farms, within 8,080,470 km2) using the USDA Animal Disease Spread Model software (v3.5.10.0). In Phase 2, we calculated the probability of detecting ≥1 infected farm as a function of producer participation, farm-level sensitivity, farm-level prevalence, and sampling frequency. The participatory design was effective: ≥90% probability of detecting the notifiable pathogen at 0.05% farm prevalence (33 positive farms among 66,637 farms) when farm-level sensitivity was ≥20% and producer participation was ≥40%. Depending on the specimen collected, the shipment method, and the test selected, costs ranged from $0.03 to $0.07 USD (€0.02 to €0.06) per pig in inventory. Thus, a surveillance design based on collecting and testing specimens from a few targeted pigs on each of many farms would be both affordable and effective at a national level.