When I started working at CDC as an EIS Officer in the Influenza program, there was a lot of focus on pigs as the source of novel influenza viruses. It was called the mixing vessel theory and in retrospect it was my introduction to the importance of infectious disease ecology to prevent microbial threats. Pigs can be infected by multiple different influenza viruses and “mix-up” their 8 genetic pieces to create a brand new or reassortant virus. The new H1N1 flu virus appearing in different parts of the world has genetic pieces from human influenza, bird influenza, and 2 different types of pig influenzas. It has been referred to as a quadruple reassortant.

In late October 2007, a hunter in Northern California shot a black bear and brought the carcass home for a community feast the next day. At least 38 people ate a variety of dishes, some of which included bear meat which was not fully cooked. Within a week, people who had attended the event started getting sick with fever, chills, and muscle aches. Over the next few weeks, 30 people became ill. Based on the clinical symptoms and the history of a common meal of bear meat, a local physician suspected Trichinella infection was causing these illnesses and notified the county health officials.