Epidemiologists study the occurrence of disease in populations. They look for both genetic and environmental factors that may lead to a disease and apply their research and analysis to prevent or minimize its spread and impact. Through careful investigations, thoughtful analysis, and clear communication, epidemiologists can help slow or stop the spread of dangerous diseases and in the process save lives.

The topics in this lesson address the Common Core State Standards for English Language Arts and Literacy in History/Social Studies, Science, and Technical Subjects, and the NRC Framework for K-12 Science Education, the foundation for the emerging Next Generation Science Standards. Environmental public health is an important subject because it affects everyone’s lives. Although it may not be referenced specifically in the standards, it can be used as an engaging jumping off point to address many of the concepts that are.

While the concept of public health may date back to antiquity, epidemiology as a scientific field is relatively new. In this video, you’ll meet John Snow, the man whom many people call the "father of modern epidemiology." As you watch, focus on Snow’s method of investigation. Click "View" on the left to watch the video.

After watching the video, explain Snow's methodology and how his investigation attempted to answer a question or test a solution to the problem. How might such an investigation be handled today?

The term epidemiology is now widely applied not only to infectious diseases like cholera, but to disease in general. In fact, many non-disease health-related conditions also fall under its umbrella.

Epidemiologists explore whether something in the environment might be the cause of a disease in an unexpectedly high number of people in a neighborhood or other defined population. However, determining a link between environmental factors and a particular disease is difficult, especially when you take genetics into account. In fact, research on the factors that influence disease and on genetic susceptibility for disease is so complex it can sometimes take decades.

In this video, you’ll learn about one woman’s struggle with a rare disease called scleroderma. As you watch this video, look for evidence of an environmental factor causing scleroderma. Consider whether you think the facts presented in the video count as evidence. Also think about what questions still remain. Click "View" on the left to watch the video.

The Common Core Standards ask students to “analyze the author’s purpose in providing an explanation, describing a procedure, or…identifying important issues that remain unresolved.” How might students analyze a resource such as this video, in which the video's producer is the "author," to perform such a task?

Epidemiologic studies can provide important insights into not just the acute or immediate health effects of environmental exposures, but also the chronic, long-term effects. These studies might generate data that are used to inform national policy decisions on healthcare.

In these videos, you’ll learn about the conditions that led to the creation of two epidemiologic studies that focus on environmental factors and their possible impact on public health. One investigates heart disease, a so-called “hidden epidemic;" the other looks at the health effects stemming from environmental pollution, such as the health effects that occurred as a result of the 2010 BP oil spill in the Gulf of Mexico. As you watch, consider the environmental factors that may have led to these health problems. Click "View" on the left to watch the two videos.

After watching the videos, describe how you think the researchers in the two studies might have established the connection between the environmental factors and the health problems.

Disease transmission is the process by which infectious diseases are spread from one organism to another. The major pathways through which infectious diseases can be spread to an individual include direct or indirect contact; airborne transmission; food, water supply, or blood contamination; and vectorborne transmission. Unlike direct transmission, in which a disease is spread from person to person, vectorborne transmission occurs when an infected organism—such as a parasite, insect, or animal—carries the disease and transmits it to another host.

In this video, learn how epidemiologists determined the vector responsible for bubonic plague, which killed about 25 million people in Asia, Africa, and Europe during the Middle Ages, was revived in China in the late 1800s, and spread to San Francisco by the early 1900s. As you watch, consider the response of the San Francisco authorities to this epidemic. Click "View" on the left to watch the video.

Describe another campaign in which a government agency used epidemiologic research to develop a public health policy.

For centuries, bubonic plague devastated the populations of three continents. Today, thanks to early treatment that can decrease the mortality rate from 90 percent to 15 percent, bubonic plague is far less prevalent than other infectious diseases. Only a few thousand cases of human plague are reported each year worldwide. This demonstrates that proper understanding of disease transmission can lead to effective control strategies.

In this video, learn about a disease for which nearly half the world's population is at risk and that kills an estimated 650,000 people each year. From an epidemiologic perspective, the basics of malaria are well known. Malaria is not spread from person to person like a cold or the flu is. Rather, a mosquito transmits disease parasites to a human. Still, the challenge is to find effective control strategies. As you watch, consider the different types of solutions being developed for management of this disease. Click "View" on the left to watch the video.

Compare and contrast the two types of solutions to the malaria problem: medical (medicine) and technological (mosquito nets). Which seems a more promising solution to this health crisis?

Some infectious diseases appear in a location unexpectedly and puzzle even the most seasoned disease experts. These are called emerging diseases. Several environmental factors may be involved in the spread of these emerging diseases: global airline travel, climate change, and development in wilderness areas.

In this video, learn about an emerging disease called West Nile Virus, which was first identified in the United States in New York City in 1999. Pay special attention to the ways in which multiple public health professionals work together to solve the mystery. Click "View" on the left to watch the video.

Describe the roles of the various professionals who might need to collaborate to solve a public health crisis.

In this lesson, you have explored the role of an epidemiologist in environmental public health and learned how you can apply this topic to your science and science literacy curriculum. Now it's time to think about how you could create your own activity that ties a topic in environmental public health to your curriculum. Begin by reviewing your responses in previous sections to see how your comments might provide inspiration for this activity. Click "review my work" above and view or print out the screen that pops up.

To broaden your options, you can review all the media in the Environmental Public Health collection and refer to your own local educational standards. Then design an activity that incorporates at least one media resource and supports at least one science and technology or science literacy standard.