This discussion is designed to help students reflect on their understandings of how the origins of diseases are tracked and their spread determined.

• What kinds of information would help an epidemiologist determine that a disease was being caused by an infectious agent rather than being a noninfectious disease?

  Students should recognize that the pattern of disease distribution can distinguish infectious diseases from heritable diseases or diseases caused by lifestyle (heart disease for example) but may be less clear-cut when it comes to diseases caused by the environment. The rates of the spread of the disease and the numbers of individuals involved should also indicate that the disease is infectious. The epidemiologist would also want laboratory data such as information on antibodies and cultures for microbial growth.

• What kinds of information about the origin of a disease can be gained from examining the symptoms of the disease?

  Students should recognize that many different diseases exhibit similar symptoms.

• How would understanding the origin of the disease and how it is spread help in stopping the hantavirus outbreak?

  Students should realize that by knowing the viral nature of the cause and that the vector that carries the virus is a mouse, treatment for victims can be administered and plans for eliminating the vector can halt the spread of the disease. You may want to share the following with your students:

• Many cultures have established rituals, taboos, and customs which, in part, were developed to avoid illnesses observed to be associated with certain hygienic or food practices. Do you know of any and, if so, is there a basis for the practice in science?

  Students may mention that certain religions forbid eating pork, a taboo that may be the result of the concern about contracting trichinosis from undercooked pork. Some cultures forbid pregnant women from drinking alcohol, which can cause developmental problems in the fetus.