CHAPTER 31 Test Your Knowledge
DRIVING QUESTION 1
What is the structure of a virus, and how do viruses cause disease?
By answering the questions below and studying Infographics 31.1 and 31.5, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
Which of the following is found in all viruses?
a. DNA
b. RNA
c. a membranous envelope
d. a protein shell
e. a cell membrane
Explain how viruses replicate within humans.
Why does poliovirus cause long-lasting damage, whereas those infected by influenza virus typically make a full recovery?
USE IT
Both viruses and bacteria can be human pathogens. Describe some key differences between them. (Hint: You may wish to refer to Chapter 14.)
Why do poliovirus, influenza virus, and HIV infections cause different symptoms?
DRIVING QUESTION 2
What is innate immunity?
By answering the questions below and studying Infographics 31.3 and 31.4, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
Name three components of the innate immune system. For each, provide a brief description of how it offers protection.
What do macrophages and neutrophils have in common?
USE IT
From what you know about innate immunity, would you predict different or identical innate responses to infections from E. coli (a bacterium) and S. aureus (another bacterium)? Explain your answer.
Neutropenia is a deficiency of neutrophils. Would you expect someone with neutropenia to be able to mount an effective inflammatory response? Explain your answer.
Why might someone taking anti-inflammatory drugs be more susceptible than others to bacterial infections?
DRIVING QUESTION 3
What is adaptive immunity, and how does vaccination rely on adaptive immunity?
By answering the questions below and studying Infographics 31.3, 31.6, 31.7, 31.8, and 31.9, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
Compare and contrast the features of innate and adaptive immunity.
B cells, plasma cells, and antibodies are all related. Describe this relationship, using words, a diagram, or both.
USE IT
Anti-hepatitis C antibodies present in a patient’s blood indicate
a. that the patient is mounting an innate response.
b. that the patient has been exposed to HIV.
c. that the patient has been exposed to hepatitis C within the last 24 hours.
d. that the patient has been exposed to hepatitis C at least 2 weeks ago.
e. that the patient has hepatitis.
Vaccination against a particular pathogen stimulates what type of response?
a. innate
b. primary
c. secondary
d. autoimmune
e. b and c
Will someone who has been exposed to seasonal influenza in the past
a. have memory B cells?
b. still be at risk for seasonal influenza next year? Why?
c. still be at risk for H1N1 (swine flu)? Why?
Staphylococcus aureus can cause a bacterial skin infection that can become very serious.
a. Why does the body exhibit innate and adaptive responses to Staphylococcus aureus but not to its own skin cells?
b. Will the innate response to Staphylococcus aureus be equally effective against Streptococcus pyogenes, another bacterium that can cause skin infections? Explain your answer.
c. Will the adaptive response to Staphylococcus aureus be equally effective against Streptococcus pyogenes? Explain your answer.
HIV is a virus that infects and eventually destroys helper T cells. Why do people with AIDS (that is, with advanced HIV infections) often die from infections by other pathogens?
MINI CASE
In 2008, there was an outbreak of measles in San Diego. The first patient was a 7-year-old unvaccinated boy who had returned home from a family trip to Switzerland. He began to develop a cough, sore throat, and fever, but continued to attend school. He was taken to his pediatrician when he developed a rash, and then was sent to the emergency room because of a very high fever. Blood tests revealed antimeasles antibodies. Eleven other children ended up developing measles; none had been vaccinated. The other cases were the 2 siblings of the first patient, 4 children in his school and 5 children who were in the pediatrician’s office at the same time as the patient. Of the 11 additional cases, 3 children were less than 1 year old. (Data are from Outbreak of measles–San Diego, California, January–February 2008. (2008) Morbidity and Mortality Weekly Report 57(8): 203–206.)
a. Why was the presence of antimeasles antibodies in the first case an important finding?
b. What can you infer about how easily measles spreads?
c. What does this case suggest about the importance of measles vaccinations?
d. Were all the unvaccinated children necessarily behind on their vaccination schedule? (Hint: Look up the recommended measles vaccination schedule on the CDC website www.cdc.gov.)
BRING IT HOME
Almost 10% of the children in the school attended by the original patient described in the Mini Case were unvaccinated because their parents had filed Personal Belief Exemptions stating that they did not want to vaccinate their children. What is your local school district or state policy on vaccinations for enrolled students? This information is typically available at the school district website or the state’s Department of Health website. From the policies in place (and whether they permit any exemptions), do you think it is possible that a measles outbreak could occur in a local school?
DRIVING QUESTION 4
What are specific features of influenza virus that allow it to cause worldwide outbreaks?
By answering the questions below and studying Infographics 31.5 and 31.10, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
What is the difference between antigenic shift and antigenic drift?
A strain of influenza can infect and replicate in birds without causing them disease. The same strain can be transmitted from birds to humans, causing severe illness in humans. What else would this strain need to be able to do in order to become pandemic?
USE IT
What processes are responsible for the emergence of pandemic influenza strains such as H1N1 swine flu? Explain how these strains can spread so successfully through the human population.
In 2013, the CDC advised people traveling to China to avoid visiting poultry farms or bird markets. Why did the CDC make this recommendation?
Why are those with influenza infections susceptible to bacterial pneumonia?
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INTERPRETING DATA
The table below gives the approximate cumulative rate of influenza hospitalizations in the United States in newborns to 4-year-olds and in people 65 years old and older for the 2009–2010 flu season and the 2012–2013 flu season. As the flu season runs from the fall of one year through the spring of the next, the data are reported by week (36th week of the first year to 12th week of the next).
a. Graph the cumulative incidence rates by week for each age group in each flu season. In plotting the data on the graph, note that the rates in the two seasons are reported differently–per 10,000 and per 100,000–and be sure your graph accounts for this.
b. Examine each season and compare and contrast the age-specific hospitalization rates in the two seasons.
c. Which of the two flu seasons is more typical? Why?
