Epidemiology is a multidisciplinary subject. Members in this field mostly includes public health care workers and scientists from related fields such as chemists, biologists, geneticists, and anthropologists. People in epidemiology may work in hospital and research settings, as well as for federal organizations such as the Centers for Disease Control and Prevention (CDC). One particular unit that may be of interest for those pursuing epidemiology is with with Epidemic Intelligence Service (EIS), a subgroup within the CDC specializing in epidemiology. Epidemic Intelligence Service officers are field workers who investigate outbreaks in the US and other countries. Their work aids in understanding causes of outbreaks and quickly stopping spread of diseases from one place to another; notably, they have contributed to helping during various pandemics in the past, such as with smallpox, polio, and Ebola.