Chapter 16: Disease and Epidemiology

Which is the most common type of biological vector of human disease?

A. viruses

B. bacteria

C. mammals

D. arthropods

D

A mosquito bites a person who subsequently develops a fever and abdominal rash. What type of transmission would this be?

A. mechanical vector transmission

B. biological vector transmission

C. direct contact transmission

D. vehicle transmission

B

Cattle are allowed to pasture in a field that contains the farmhouse well, and the farmer's family becomes ill with a gastrointestinal pathogen after drinking the water. What type of transmission of infectious agents would this be?

A. biological vector transmission

B. direct contact transmission

C. indirect contact transmission

D. vehicle transmission

D

A blanket from a child with chickenpox is likely to be contaminated with the virus that causes chickenpox (Varicella-zoster virus). What is the blanket called?

A. fomite

B. host

C. pathogen

D. vector

A

Which of the following would NOT be considered an emerging disease?

A. Ebola hemorrhagic fever

B. West Nile virus fever/encephalitis

C. Zika virus disease

D. Tuberculosis

D

Which of the following would NOT be considered a reemerging disease?

A. Drug-resistant tuberculosis

B. Drug-resistant gonorrhea

C. Malaria

D. West Nile virus fever/encephalitis

D

Which of the following factors can lead to reemergence of a disease?

A. A mutation that allows it to infect humans

B. A period of decline in vaccination rates

C. A change in disease reporting procedures

D. Better education on the signs and symptoms of the disease

B

Why are emerging diseases with very few cases the focus of intense scrutiny?

A. They tend to be more deadly

B. They are increasing and therefore not controlled

C. They naturally have higher transmission rates

D. They occur more in developed countries

B

Match each term with its description.

___ sporadic disease

___ endemic disease

___ pandemic disease

___ morbidity rate

___ mortality rate

A. the number of disease cases per 100,000 individuals

B. a disease in higher than expected numbers around the world

C. the number of deaths from a disease for every 10,000 individuals

D. a disease found occasionally in a region with cases occurring mainly in isolation from each other

E. a disease found regularly in a region

A- morbidity rate

B- pandemic disease

C- mortality rate

D- sporadic disease

E- endemic disease

Match each pioneer of epidemiology with his or her contribution.

___ Florence Nightingale

___ Robert Koch

___ Joseph Lister

___ John Snow

A. determined the source of a cholera outbreak in London

B. showed that surgical wound infection rates could be dramatically reduced by using carbolic acid to disinfect surgical tools, bandages, and surgical sites

C. compiled data on causes of mortality in soldiers, leading to innovations in military medical care

D. developed a methodology for conclusively determining the etiology of disease

A. John Snow

B. Joseph Lister

C. Florence Nightingale

D. Robert Koch

The ________ collects data and conducts epidemiologic studies in the United States.

Centers for Disease Control and Prevention, or CDC

________ occurs when an infected individual passes the infection on to other individuals, who pass it on to still others, increasing the penetration of the infection into the susceptible population.

Propagated spread

A batch of food contaminated with botulism exotoxin, consumed at a family reunion by most of the members of a family, would be an example of a ________ outbreak.

point source

A patient in the hospital with a urinary catheter develops a bladder infection. This is an example of a(n) ________ infection.

nosocomial or healthcare-associated

A ________ is an animal that can transfer infectious pathogens from one host to another.

vector

The ________ collects data and conducts epidemiologic studies at the global level.

WHO (World Health Organization)

During an epidemic, why might the prevalence of a disease at a particular time not be equal to the sum of the incidences of the disease?

Some of the affected individuals may no longer be infected or may have died.

In what publication would you find data on emerging/reemerging diseases in the United States?

The Morbidity and Mortality Weekly Report, or MMWR

What activity did John Snow conduct, other than mapping, that contemporary epidemiologists also use when trying to understand how to control a disease?

Snow tracked affected individuals and gathered data from them to look for common experiences that might explain the outbreak.

Differentiate between droplet vehicle transmission and airborne transmission.

Both are caused by saliva or mucus coughed or sneezed out from an infected individual. Droplets are moderately large, though, and will fall to the ground (or other surfaces) in roughly a one-meter diameter around the producing individual. In airborne transmission, microdroplets coughed or sneezed out will dry out very rapidly, being able to be carried on air currents much further away from the individual who released them.

Many people find that they become ill with a cold after traveling by airplane. The air circulation systems of commercial aircraft use HEPA filters that should remove any infectious agents that pass through them. What are the possible reasons for increased incidence of colds after flights?

Airborne viruses are not the only possible route of transmission. In an aircraft cabin, people sit in very close quarters and the opportunity for direct contact is high. Infectious agents may also get onto the arm rests and other fomites on the plane, leading to indirect transmission.

An Atlantic crossing by boat from England to New England took 60-80 days in the 18th century. In the late 19th century the voyage took less than a week. How do you think these time differences for travel might have impacted the spread of infectious diseases from Europe to the Americas, or vice versa?

Due to the length of the voyage in the 1700s, all susceptible passengers on the ship would either die or recover from the illness long before the ship reached its destination. Thus, there would be less likelihood of the pathogens surviving long enough to be transmitted to the New World. This wasn't true in later times, as incubation periods and active illness periods might persist from before the infected individual leaves until after they arrive to their destination, meaning they could more easily pass the infectious agent from continent to continent.

Why might an epidemiological population in a state not be the same size as the number of people in a state? Use an example.

An epidemiological population includes only the people at risk or relevant to a specific study, not the entire state population.

Example:
If a study is tracking Zika virus in pregnant women, the epidemiological population is only pregnant women in the state—not everyone living there. So, even if the state has 5 million people, the study might only focus on 100,000 pregnant women.