Chapter 16 New Infectious Threats

Overview

In Chapter 15, we saw how a new disease, HIV/AIDS, quickly spread around the globe, but many other diseases have also seen major changes in patterns of infection worldwide. Some of these infectious diseases are caused by bacteria instead of viruses. Unlike viral diseases, bacterial diseases can generally be treated by antibiotics. For the last half of the twentieth century, people thought that antibiotics would make widespread bacterial disease a thing of the past. Over time, however, many species of bacteria have, become resistant to antibiotics.

              In this chapter, we will mainly focus on human diseases. Keep in mind, however, that all organisms can suffer from disease. Production of disease-resistant strains of plants has been a major goal of both traditional plant breeding and of genetic engineering of plants (see Chapter 17). Diseases of agriculturally and domestically important animal species have long been a focus of research in veterinary medicine. Diseases among wild animal and plant species are a research focus in ecology because of their importance to the health of wild populations and because of their interaction with human disease. 

Although a particular organism can be demonstrated to be the causative agent of a disease (Chapter 15), there are many other factors that contribute to the spread of the disease in populations. The development of treatments for specific diseases in individuals depends on knowledge of the pathogen. However, development of public health strategies to prevent the spread of disease depends just as much on knowledge of the routes of transmission of the pathogen. One disease, smallpox, has been eliminated entirely.  However, according to the Centers for Disease Control and Prevention (CDC), some 30 new infectious diseases, including AIDS, SARS, MERS, and COVID-19, have emerged in the past few decades as technology and lifestyles have changed. Other infectious diseases have been with us for millennia; they may cycle through long periods of quiescence, only to re-emerge as epidemics once more.

Chapter Outline

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Review Questions

THE PURPOSE of these review quizzes is to guide students in where their knowledge and understanding is strong, where it is weak, and where time should best be spent in studying.

CHAPTER 16:

  1. What is a pathogen?  What is virulence?  How does virulence tend to evolve over time?  What is the difference between prevalence and incidence?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 16.1.)
  2. Name at least four sexually transmitted diseases.  Which ones are most common?  What can be done to minimize the risks for acquiring these diseases?  What is the history of tuberculosis infection in various parts of the world, and how have these patterns changed in recent decades?  What are some other diseases that have recently spread by direct contact?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 16.2.)
  3. What is Creutzfeld-Jacob disease, and how does it spread?  How does it affect different species?  What can be done generally to protect populations against foodborne illnesses? What practices allow foodborne illnesses to spread?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 16.3.)
  4. Name at least five waterborne illnesses.  Explain how they spread. Which ones are no longer as prevalent as they once were?  How do epidemics of these diseases occasionally emerge, and what can be done to prevent such outbreaks?  What is a pandemic?  What measures can best prevent the spread of such diseases as cholera, Legionnaire’s disease, or waterborne parasites? (If you cannot explain these things, or if you are not sure, then you need to reread Section 16.4.)
  5. Name three aerosol-dispersed diseases that have caused outbreaks in recent decades.  How are these outbreaks generally contained?  Why was it so difficult to contain the outbreak of COVID-19?  What is now being done to contain this disease?  What problems have arisen in the responses to COVID-19?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 16.4.)
  6. What is a disease vector?  Name at least five diseases spread by vectors.  What can be done to control these diseases?  Which vector-borne diseases affect the areas where you live?  Which ones are more prevalent in other parts of the world?  Why does climate change affect the prevalence of these diseases?  What can you do to best protect yourself against various vector-borne diseases? (If you cannot explain these things, or if you are not sure, then you need to reread Section 16.5.)

Open Response Study Questions

These questions are designed to assess your understanding of the topics explored in this chapter. You can use these questions in three ways:

Before you start …

Read through the questions before you read the chapter to help prime you to read the text more carefully and strategically. Remember that you are just starting out on your learning journey, so don’t feel disheartened if you don’t know how to answer them yet!

Whilst you read …

As you work through the chapter, have another go at answering the questions to see how you are progressing. You can also answer the questions with the textbook open in front of you, in order to create model answers that can be used to refer back to later.

At the end …

Answer the questions once you have finished reading to see what you have learned. Check your responses against your model answers and use these to identify any gaps in your understanding.

DEFINITIONS:

In your own words, define ANY TWO of the following terms:

prion                Chlamydia      virulence         Legionnaire’s disease              West Nile virus

Creutzfeld-Jakob disease        cholera            vector species                         primary host

ESSAYS:

Answer any two of the following questions.  Make sure to answer all parts of any question you choose.

1. Select two infectious diseases whose frequency increased in the last 50 years.  Tell what you know about (a) their

    causes & symptoms, (b) factors that promote their spread, and (c) remedies that are used to contain the spread.

2. (A) Explain the difference between a primary host, a dead-end host, and a vector species.  (B) Describe a disease

    that illustrates these concepts.

PowerPoint Slides

Download Version A (Illustrations only)
Download Version B (Topic outlines also)

Bibliography

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Chapter 17
Plants to Feed the World