Factors in the Increase in Emerging and Re-emerging Disease

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About This Module 

Topics: Human health, epidemiology, pathogens, emerging and re-emerging disease, global issues affecting disease, ecology effects on disease occurrence, climate change effects on disease occurrence

Grade levels: 9-12


Students take on roles of teams of National Institutes of Health (NIH) scientists preparing to address a World Health Organization (WHO) international panel on the critical issue of emerging infectious disease. They present their research and make recommendations for countering the major cause of increased outbreaks.

What factors will they present? Which factor will they decide is the major factor increasing outbreaks worldwide? What recommendations will they make to reduce disease outbreaks?

Learning Objectives 

To better understand the factors that lead to an increase in emerging and re-emerging disease, students should be able to:

  • Explain the difference between emerging disease and re-emerging disease.
  • List examples of infectious disease occurrence that are linked to factors that increase incidence of emerging and re-emerging disease.
  • Describe factors that can influence the increase in emerging and re-emerging disease, including ecological, environmental, demographic, and epidemiological factors.
  • Explain the seriousness of the global problem of emerging and re-emerging disease.
  • Describe how changing the ecology of an area can increase disease occurrence.
  • Explain the impact that disease can have on worldwide populations in terms of scale, severity and quality of life.



Next Generation Science Standards

Standards Aligned to PBL Modules

Scenario (with possible answers)  

Aerial view of Geneva, Switzerland.As a research scientist working for the National Institutes of Health (NIH), you have been

investigating infectious disease and gathering data worldwide for months. You and your team have visited remote locations in dense jungles in Gabon to track down disease contacts, walked rolling savannas in Ethiopia to investigate possible disease vectors, and taken water samples in overcrowded inner cities in Haiti looking for contaminants. You have compiled research on varying aspects of disease characteristics and your colleagues are now gathering to share their experiences and preliminary findings with other teams from worldwide health agencies.

You and your team of investigators are going to address a World Health Organization (WHO) international panel on the critical issue of emerging infectious disease at WHO headquarters in Geneva, Switzerland. Other teams of investigators will also be presenting the results of their studies around the world. Your fellow scientists are also friends. They are returning from some of the world’s hot spots of disease—some of the same locations that you have visited. You have many stories to share; you are glad to see them again, but everyone knows what huge tasks lay ahead.

Recent outbreaks of emerging and re-emerging diseases have alarmed you and other experts in your field. Diseases occurring in more frequent outbreaks and in regions that have never experienced certain diseases before are causes for concern.

microscope image of the Zika virus (red spheres)
Transmission electron microscope image of the Zika virus (red, spherical shapes). Image: CDC/Cynthia Goldsmith. https://phil.cdc.gov/phil/details.asp

With each new outbreak, the public call for answers increases, only to quickly fade when the crisis appears to be over. You think of the Zika virus outbreak that spread from many Central and South America countries to the U.S.  The public did not particularly care about a relatively unknown virus that appeared sporadically in Africa. When it caused devastating birth defects in Brazil and traveled to the U.S., it certainly got some attention. Months later, with colder weather affecting the mosquito vector that carries Zika virus, the outbreak died out –and so did public interest in infectious disease threats.

You know that the threat didn’t go away. You know the next outbreak is out there ready to strike; recent outbreaks have proven that. Outbreaks of novel viruses, antibiotic-resistant strains of deadly bacteria, and re-emerging diseases have increased dramatically in the last few years. Why?


The WHO has convened an international panel of scientists, epidemiologists, and public health officers to discuss the potential causes of the increased disease occurrences and to construct a formal plan to address the issue. With the major international conference looming, you must now analyze the information and the data you have collected to decide which factor has the most detrimental effect on contributing to increased deadly infectious disease outbreaks around the world.

This conference requires more than a standard report citing data and displaying results in tables and graphs. Analysis of the various factors that contribute to emerging infectious diseases will be required to fully present an accurate picture of the state of infectious disease in the world today.

You and your team will be presenting your research and conclusions to the international panel and will participate in the discussion, draw conclusions, and make recommendations for countering the major cause of increased outbreaks of emerging and re-emerging diseases. You will need a thorough understanding of the major factors causing the increases in order to choose the one factor that is most responsible. This is a difficult task. The panel will decide which factor to address based on the evidence you present. If they agree with your assessment, your team may be chosen to lead the worldwide effort to mitigate the impact.

Guiding Questions:

  1. What are the causes of increasing outbreaks of emerging and re-emerging infectious diseases worldwide?

            What factors have led to an increase in infectious diseases in different regions of the world?         How widespread is each factor?

Examples of each factor are listed in the “Factors in the Increase of Emerging and Re-emerging Infectious Disease” support material, but students should list and explain others found in their research.

  1. What diseases are generally caused by the different factors?

            What are the effects of the diseases?  What are the death rates for the diseases? How serious are the consequences if a person survives? How many people are generally affected?

Examples of each factor-linked disease are listed in the “Factors in the Increase of Emerging and Re-emerging Infectious Disease” support material, but students should list and explain others found in their research.

  1. What is you and your team’s choice for the factor which contributes most to the increasing numbers of infectious disease outbreaks?

Be able to defend your choice to the panel.
Does your choice for the most influential factor worldwide differ from the factor for the U.S.? Explain.

Student answers will vary. The important outcome is that they are able to defend their choice based on sound scientific reasoning. You (and they) may find that the student groups use differing criteria for their choice. One group may emphasize mortality rates in their choice while another group emphasizes the feasibility of the decreasing the occurrence of a particular disease. Whatever the reasoning, their decision should contain the science content to defend their choice.

  1. The panel must agree on the leading factor that causes an increase in emerging and re-emerging disease outbreaks/epidemics. What evidence led you and your team to decide on that factor?

            Did factors presented by other teams cause you to change your mind? Explain.

Student answers will vary. Stress the importance of the panel agreeing on a leading factor so that factor can be addressed and disease occurrence can be reduced.

  1. After the panel agrees on a factor, what recommendations do you and your team have for mitigating the effects of the factor or for eliminating it? Be specific.

            What can be done to decrease the incidences of emerging and re-emerging disease?

What are the pros and cons of each strategy? (Example: A strategy may be effective in killing a pathogen, but too expensive for many third-world countries to implement.)

Student answers will vary.

Sample Rubric 

Information about constructing and implementing rubrics for problem-based learning strategies can be found in Developing Rubrics in the Teacher Professional Development section.


 Invite your county or district public health officer or an epidemiologist from a local university (or both) to talk to your classes about how public health is monitored in your area.

►As part of the module, student teams selected their choices for the factor has the most detrimental effect on contributing to increased deadly infectious disease outbreaks worldwide. After hearing all the student group presentations, have the class vote on which factor contributes most to the increasing numbers of infectious disease outbreaks. Tell them their grade does not depend on the factor being chosen; they should now play the part of the WHO evaluators and choose the factor that will be best addressed and that has the most possibility for mitigation and control. Students should be able to defend their selection. Hopefully, the teams will not just choose their own factor if there is a better case to be made for another team’s choice.

► Relate some of the factors to the students’ environment and discuss how these factors affect disease in their city or state. Some of the factors that affect disease outbreaks may be present in your area, depending on your location. For example, not all locations have good quality health care systems or even a health care system at a reasonable driving distance. Locations in southern US have outbreaks, such as Zika, that are influenced by climate change and vector migration into newly favorable environments. The mosquito that carries malaria now thrives in Gulf coastal states and could potentially cause malarial outbreaks. Every location carries risks of disease outbreaks.

► You may want to remind them of possible career interests after they have worked through the module. You may want to discuss what the funding would mean for them as epidemiologists and researchers in real life. Years of funding provide financial security, opportunities for travel around the world to study all facets of the infectious disease in varying locales, possible research study publications which greatly further their careers making future funding more likely, the prestige of winning such an important research project, presentations at international conferences, and of course, the rewarding experience of being able to make such a significant contribution to world health. Ask:  How would you feel knowing you had helped eradicate a global health problem and saved many lives?


Additional Resources 

Additional resources about emerging and re-emerging disease can be found:

in the Key Resources section in the Pandem Disease Center at

in the Emerging and Re-emerging Disease Funding module background materials (Internet Resources for Emerging and Re-emerging Diseases)