Thus, the USDA's ultimate goal is to eliminate livestock as a reservoir. When the agency announced it was planning for this program, it noted that two vaccine candidates were in trials. Until these are validated, it plans to use the standard playbook for tackling emerging infections: contact tracing and isolation. And it has the ability to force livestock and their owners to be more cooperative than the human population turned out to be.
The five-step plan
The USDA lists isolation and contact tracing as phase 3 of a five-phase plan for controlling H5N1 in cattle, with the two earlier phases being mandatory sampling and testing, which must be handled on a state-by-state basis. Following successful containment of the virus in a state, the USDA will proceed with batch sampling to ensure each state remains virus-free. This is essential as we do not have a clear picture of how often the virus has jumped from its normal reservoir in birds into the cattle population.
That means reaching Phase 5, which the USDA calls “Demonstrating Freedom from H5 in US Dairy Cattle,” may prove impossible. Dairy cattle are likely to have daily contact with birds, and the virus may be regularly reintroduced into the population, leaving containment as the only option until vaccines are ready.
The testing will initially focus on states where transmission from livestock to humans is known to have occurred or where the virus is known to be present: California, Colorado, Michigan, Mississippi, Oregon and Pennsylvania. If you would like to follow the progress of the USDA's efforts, it will post weekly updates.
