Public health workers try to understand why an illness is spreading within a community, or what can be done to stop people from getting hurt in a workplace. In a way, they are like detectives looking for answers to an unsolved mystery. They interview people, study medical records, and try to make sense of the clues they gather.

Public health workers are different from medical practitioners—people who practice medicine and treat individuals for regular checkups or after they have become sick or injured. Public health workers identify and understand disease transmission and help communities prevent disease from spreading.

In this lesson, we will look at what happens when there is a suspected outbreak—a sudden increase—of a disease. Using an actual case, you’ll see how these public health workers solved a public health mystery and protected the communities they serve.

Goals
Here are the big ideas you will learn about in this lesson:

• Public health investigations follow a step-by-step process.
• Health professionals from many fields play a role in protecting the public health.
• Collaboration is important in public health investigations.

Strategies
You will be using many reading and writing strategies to complete this lesson. The key strategies that you will focus on are:

• Making inferences
• Sequencing events
• Understanding problem/solution
• Determining important information
• Constructing summaries

• outbreak
• symptom
• transmission

Understanding the source of transmission—how a disease is passed from one organism (living thing) to another—can help stop its spread. If someone suspects a certain illness is caused by an infection—when a disease-carrying organism enters a body—public health workers can recommend something to slow or stop the spread of disease in a community or population.

In this video, you will learn more about the process public health workers use in an outbreak investigation. The video features a case in which public health workers were challenged to solve a mystery: What caused the outbreak of a deadly disease? Watch as people from different medical and health fields work together to solve the mystery and fight the transmission of the disease.

Click "View" on the left to watch the video.

Tracey McNamara, Debbie Asnis, and Annie Fine are all doctors in New York City. One works for a zoo, one for a hospital, and one for the city's department of health. How is what they do similar?

As the different health professionals in the video tried to determine the cause of the disease, they followed steps in a process. However, investigating a disease outbreak is often complicated. Some steps may not apply or follow an exact order. As is often the case in science, investigators have to be creative and keep at it until they find the answers they are looking for.

When doctors or hospitals report cases of unusual illness, a public health office's first response is to check that the information it receives, including any initial diagnosis, is accurate. To confirm that there really is an outbreak, a team of public health staff may need to collect further information. They may make observations, take samples from the field, and interview patients, their families, and neighbors. The team may also make calls to other hospitals or public health offices to learn if additional cases are being reported.

In this video, you'll see more steps that were taken in the outbreak investigation process, including lab tests run at the Centers for Disease Control and Prevention (the CDC)—the nation's public health agency. You’ll also learn why it can be important in science to question findings and suggest other explanations.

Click "View" on the left to watch the video.

After the initial investigations were completed, there was a breakthrough. Lab tests showed that the virus affecting humans was a form of encephalitis (en-seh-fah-LIE-tis). Encephalitis is a disease whose most serious symptom—or sign—is swelling of the brain. This matched the symptoms of patients in the New York hospital. The source of transmission for encephalitis is mosquitoes. This also matched clues that public health workers had found in their investigations.

However, not everyone was convinced that the initial diagnosis was correct. It took collaboration—people working together—among different health fields for the disease to be correctly diagnosed as West Nile virus.

Write down two to three sentences to explain how the doctor at the zoo helped the investigators determine that West Nile virus was the cause of the outbreak.

In this lesson, you’ve learned that public health professionals have an important responsibility: looking out for the public health. Now you will read how diseases like the West Nile virus, which spread from animals to humans, show the growing importance of collaboration to protect the public against disease.

Click "View" on the left to open the reading passage. After you have read it, answer the following question.

Why do you think it's in the public's best interest for doctors and veterinarians (animal doctors) to share information?

Show what you have learned so far about West Nile virus and public health investigations in general by answering these three questions. Be sure to save all your answers before you go to the next screen.

You will now check your understanding of the vocabulary words for this lesson by placing them in sentences. Click "View" on the left to begin the activity.

Before moving to the next screen, choose two words from the vocabulary list and write a new sentence for each word.

Vocabulary words: collaboration, infection, investigation, outbreak, symptom, transmission

As the videos and passage explained, public health workers conduct careful investigations to identify the cause of disease outbreaks. Their work can help slow or stop the spread of disease, which can save lives.

In this activity, you will sort information according to when each step takes place in a disease outbreak investigation. Here is the problem: A patient enters a hospital with unusual symptoms. A doctor diagnoses an illness and reports it to the public health office you work in. Is this the start of a disease outbreak? What steps should you take to find out?

Click "View" on the left to begin the activity. Your teacher will review the answers with you.

Then, before moving on to the final assignment, you may want to watch this lesson's videos again or reread the passage.

Mystery Illness in New York City

Video: 2m 57s

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Mystery Solved! West Nile Virus

Video: 2m 08s

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Working Together to Improve the Public Health

Document

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In this lesson, you have learned about the importance of disease outbreak investigations in protecting public health. You have also learned that the success of these investigations often relies on several different health partners communicating their information and ideas with one another. You will now write an essay that shares what you have learned and what you think about it.

Begin by reviewing your notes. Click "review my work" above and view or print out the screen that pops up.

Final Assignment Instructions

• Click Solving a Public Health Problem—Final Assignment (PDF).
• Choose one of the topics in the PDF and write an essay.
• Organize your response so that it includes at least three supporting details that you have learned from the reading passage, video(s), and other materials in this lesson.
• Use at least three vocabulary words (or form of the words) as part of your supporting details. For example, for the word jump, you could use jumps, jumped, or jumping.