Chapter 16 study guide

Question 1

The field of _____ concerns the geographical distribution and timing of infectious disease occurrences and
how they are transmitted and maintained in nature, with the goal of recognizing and controlling outbreaks.

Answer 1

epidemiology

Question 2

The state of being diseased is called

Answer 2

morbidity

Question 3

The_______ can be expressed as the number of diseased individuals out of a standard number of individuals
in the population, such as 100,000, or as a percent of the population.

Answer 3

morbidity rate

Question 4

A _____rate can be expressed as the percentage of the population that has died from a disease or as the number of deaths
per 100,000 persons (or other suitable standard number).

Answer 4

mortality

Question 5

is the number, or proportion, of individuals with a particular illness in a given population at a point in
time.

Answer 5

prevalence

Question 6

is the number or proportion of new cases in a period of time.

Answer 6

incidence

Question 7

diseases that are seen only occasionally, and usually without geographic concentration, are called ?

ex. tetanus, rabies, and plague

Answer 7

sporadic diseases

Question 8

Diseases that are constantly present (often at a low level) in a population within a particular geographic region are
called

ex. malaria

Answer 8

endemic disease

Question 9

Diseases for which a larger than expected number of cases occurs in a short time within a geographic region are
called

ex. influenza

Answer 9

epidemic

Question 10

An ______ that occurs on a worldwide scale is called a pandemic disease

ex. HIV/AIDS and novel influenzas virus

Answer 10

pandemic

Question 11

The main national public health agency in the United States is __________, an agency of the Department of Health and Human Services.

Answer 11

CDC

Question 12

was a British physician known as the father of epidemiology for determining the source of
the 1854 Broad Street cholera epidemic in London.

Answer 12

Jon Snow

Question 13

In an _______, data are gathered from study participants through measurements (such as physiological
variables like white blood cell count), or answers to questions in interviews (such as recent travel or exercise
frequency).

Answer 13

observational study

Question 14

_________ gather data from the past on present-day cases. Data can include things like the medical
history, age, gender, or occupational history of the affected individuals.

Answer 14

retrospective studies

Question 15

are typically retrospective and compare a group of individuals with a disease to a similar
group of individuals without the disease.

Answer 15

case control studies

Question 16

follow individuals and monitor their disease state during the course of the study. Data on the
characteristics of the study subjects and their environments are gathered at the beginning and during the study so
that subjects who become ill may be compared with those who do not.

Answer 16

prospective studies

Question 17

involve manipulation of subjects, they are typically more difficult and sometimes impossible
for ethical reasons.

Answer 17

experimental studies

Question 18

can be living organisms or nonliving sites. Nonliving reservoirs can include soil and water in the environment. These
may naturally harbor the organism because it may grow in that environment. These environments may also become
contaminated with pathogens in human feces, pathogens shed by intermediate hosts, or pathogens contained in the
remains of intermediate hosts.

Answer 18

reservoirs

Question 19

For pathogens to persist over long periods of time they require ____ where they normally reside.

Answer 19

reservoirs

Question 20

A ____ is contaminated with the pathogen and can mechanically transmit it to another host; however, a passive
carrier is not infected.

Answer 20

passive carrier

Question 21

For example, a health-care professional who fails to wash his hands after seeing a patient
harboring an infectious agent could become a passive carrier, transmitting the pathogen to another patient who
becomes infected.

Answer 21

passive carrier

Question 22

is an infected individual who can transmit the disease to others

Answer 22

active carrier

Question 23

For example, _______ may transmit the disease during the
incubation period (before they show signs and symptoms) or the period of convalescence (after symptoms have
subsided).

Answer 23

active carriers

Question 24

Active carriers who do not present signs or symptoms of disease despite infection are called

Answer 24

asymptomatic carriers

Question 25

Pathogens such as hepatitis B virus, herpes simplex virus, and HIV are frequently
transmitted by

Answer 25

asymptomatic carriers

Question 26

In parasitic infections, the parasite’s preferred host is called the

Answer 26

definitive host

Question 27

In parasites with complex life
cycles, the ______ is the host in which the parasite reaches sexual maturity.

Answer 27

definitive host

Question 28

includes direct contact or indirect contact

Answer 28

contact transmission

Question 29

Here the agent is transmitted by physical contact between two individuals
through actions such as touching, kissing, sexual intercourse, or droplet sprays.

can be categorized as
vertical, horizontal, or droplet transmission.

Answer 29

direct transmission

Question 30

Often, contact between mucous membranes is required for entry
of the pathogen into the new host, although skin-to-skin contact can lead to mucous membrane contact if the new
host subsequently touches a mucous membrane.

Answer 30

horizontal direct contact transmission

Question 30

occurs when pathogens are
transmitted to a fetus or infant during pregnancy, birth, or breastfeeding.

Answer 30

vertical direct contact transmission

Question 31

When an individual coughs or sneezes, small droplets of mucus that may contain pathogens are ejected. This leads
to direct

Answer 31

droplet transmission

Question 32

involves inanimate objects called fomites that become contaminated by pathogens
from an infected individual or reservoir

Answer 32

indirect contact transmission

Question 33

For example, an individual with the common cold may
sneeze, causing droplets to land on a fomite such as a tablecloth or carpet, or the individual may wipe her nose and
then transfer mucus to a fomite such as a doorknob or towel.

Answer 33

indirect contact transmission

Question 34

The term _____ refers to the transmission of pathogens through vehicles such as water, food, and
air.

Answer 34

vehicle transmission

Question 35

Although droplet transmission over short distances is considered ______ as discussed above,

longer distance transmission of droplets through the air is considered

Answer 35

contact transmission

vehicle transmission

Question 36

Tuberculosis is often transmitted via airborne transmission when the causative agent, Mycobacterium tuberculosis,
is released in small particles with

Answer 36

coughs

Question 37

Because tuberculosis requires as few as ______to initiate a new
infection, patients with tuberculosis must be treated in rooms equipped with special ventilation, and anyone
entering the room should wear a mask.

Answer 37

10 microbes

Question 38

an animal
that carries a pathogen from one host to another without being infected itself. For example, a fly may land on fecal
matter and later transmit bacteria from the feces to food that it lands on; a human eating the food may then become
infected by the bacteria, resulting in a case of diarrhea or dysentery

Answer 38

mechanical vector

Question 39

that transmits the
pathogen from one host to another (Figure 16.12). Arthropods are the main vectors responsible for biological
transmission (Figure 16.13). Most arthropod vectors transmit the pathogen by biting the host, creating a wound that
serves as a portal of entry. The pathogen may go through part of its reproductive cycle in the gut or salivary glands of
the arthropod to facilitate its transmission through the bite.

Answer 39

biological vectors

Question 40

carries a pathogen on its body from one host to another, not as an infection

Answer 40

mechanical vector

Question 41

carries a pathogen from one host to another after becoming infected itself.

Answer 41

biological vector

Question 42

Infections acquired in health-care facilities, including hospitals, are called

Answer 42

nosocomial infections or healthcare
associated infections (HAI)

Question 43

In 2011, more than 720,000 ____occurred in hospitals in the United States, according to the CDC.

Answer 43

HAI