Surveillance and Public Health

Yolo County Under Surveillance
September 10, 2009
Ada Barros-Heiser, Health Educator and Beth Gabor, Yolo County Public Information Officer

The stakeout is on-going. The devoted epidemiologist up all night waiting, watching, hoping the dreaded disease will come out of hiding. If this happens, the epidemiologist will be hot on its tracks, ready to catch the disease in the act of taking out another victim. One could think this is how the Yolo County Health Department conducts surveillance? While most have heard the term, most likely in TV cop shows, few actually know how it works in public health. Surveillance is one of the most important responsibilities of a health department.

According to the Centers for Disease Control and Prevention (CDC), public health surveillance is “the ongoing systematic collection, analysis, and interpretation of health data essential to the planning, implementation and evaluation of public health practice, closely integrated with the timely dissemination of these data to those who need to know.” What does that really mean?

The first real surveillance-related public health action likely occurred during the bubonic plague, when health authorities boarded ships near the Republic of Venice to prevent people ill with plague-like illness from disembarking. In more modern times, surveillance data is used to assess public health status, define priorities, evaluate programs and conduct research. In Yolo County, surveillance tells the health officer where the problems exist, who is affected, and where programmatic and prevention activities should be directed.

It is important to note that collecting data is merely one step in carrying out surveillance. Public health and medical communities must also be able to share data with each other and key policymakers to take action to control and prevent disease, especially during an outbreak, such as the current H1N1 pandemic. Through surveillance, epidemiologists at the CDC have been able to identify key information concerning H1N1, such as risk factors for infection and illness, how easily the disease is transmitted, and how long people are potentially infectious. This data helped establish public health policy and guidelines on who has priority to receive vaccine, what health care workers must do to prevent infection, and how long people need to stay home so as not to infect others.

Surveillance is also important during non-outbreak times to provide baseline measurements which serve as important references in future outbreaks. In non-outbreak disease situations, quality health information is also essential for planning and implementing health policy. In the 1990s, surveillance concepts were applied to new areas of public health practice such as chronic disease, environmental and occupational health, and injury control. Risk factor data are especially important as predictors of future disease or injury. Many health and safety laws are a product of surveillance, such as helmet and seatbelt laws, where data demonstrated those most likely to survive motorcycle and vehicle crashes used helmets and seatbelts. Today, surveillance is used to implement policies to help control and direct resources towards public health issues such as obesity.

In real life, the public health epidemiologist may not be waiting in a car on a stake-out to catch a killer, but he or she most definitely helps to identify and possibly predict the killer’s next moves. By doing so, the Yolo County Health Department can control and prevent disease, and save lives.