We discuss three acellular infectious agents in this module - viruses, prions and viroids. Infection by any one of these can have serious consequences to human health and/or economic wellbeing. In the event of an outbreak, it is important to be able to identify and contain these pathogens to avoid potentially deadly outbreaks. Your assignment is to choose one of the three infectious agents and consider the epidemiological features of your selection. By epidemiological features we mean: Can you characterize the causative organism? Where does the disease come from? Who is affected? How do they acquire the pathogen? What are the symptoms and risk factors? How is the disease dealt with once it is discovered in order to prevent its spread? You can choose one pathogen based on the general scenario described below.

For this assignment you now work for the United States Department of Agriculture's Agriculture Research Service. You have been assigned to characterize a new epidemic that has spread rapidly at a farm in Montana. You arrive at the farm observe the livestock, crops and farm workers for signs of illness. You sample the fluids and tissue of several affected organisms and bring them to a state-of-the-art USDA laboratory for analysis. The outbreak is fictional but all the information - from the organism, to how it is acquired, to the symptoms it causes - should be legitimate for the infectious agent. I have intentionally left out these and other details in the scenario. You will fill in the details in your essay by addressing the following questions.

• What is the affected organism (animal/plant/human or any combination)?
• What are the symptoms exhibited by the affected organism(s)?
• What is the pathogen that you have identified after analysis of the infected material?
• How where you able to identify the agent in a laboratory?
• Describe the etiology. How did the infection make its way to the farm?
• Trace the fictional outbreak from its origins either locally, nationally or internationally.
• Knowing how the infectious agent is disseminated, what recommendations do you make to the farm manager for containment and treatment of infected organisms?