Chapter 14

What is the role of epidemiology?

To learn how to treat and prevent various diseases.

Which is an example of vehicle disease transmission?

The presence of Listeria on undercooked chicken served for dinner

Epidemiology

The science that deals with when diseases occur and how they are transmitted.

Which of the following best describes why West Nile Virus is considered to be an emerging infectious disease?

West Nile virus outbreaks have increased in number and affected areas since 1937.

pandemic

a disease that affects a large number of people in the world in a short time

sporadic

a disease that affects a population occasionally

chronic

a disease that develops slowly and lasts for months

endemic

a disease that is constantly present in a population

acute

a short-lasting primary infection

inapparent

infection characteristic of a carrier state

Biological transmission differs from mechanical transmission in that biological transmission

involves reproduction of a pathogen in an arthropod vector prior to transmission.

Which of the following is considered a major category of transmission of disease?

Contact, vehicle, and vector transmission

Which of the following is the best mode of controlling the spread of West Nile infections?

Limit exposure to mosquitoes to prevent the transmission of West Nile virus.

Which of the following is NOT a verified exception in the use of Koch's postulates?

Some diseases are noncommunicable.

incidence

number of new cases of a disease

Which of the following is NOT a communicable disease?

tetanus

Why are invasive procedures likely to increase the risk of nosocomial infections?

These procedures allow microbes from the skin to enter the bloodstream of the patient.

Which of the following is a fungal zoonosis that can be transmitted by direct contact?

ringworm

Which of the following statements about biological transmission is FALSE?

Houseflies are an important vector.

A host is not considered diseased until an infection changes one's state of health.

True

Testing the effectiveness of a new drug for anthrax would be best performed as an experimental study.

True

The yeast Candida albicans does not normally cause disease because of

antagonistic bacteria.

primary infection

an initial illness

Reservoirs of infection

- a hospital - a sick animal - a sick person - a healthy person

Predisposing factors of disease

- climate - occupation -lifestyle -genetic background

Which of the following characteristics do commensalism, mutualism, and pathogenicity have in common?

- life cycle coordination between the host and symbiont -common physical requirements between the organisms

During his research on West Nile virus, Bill learned that this virus is placed within a functional grouping known as arboviruses. What is meant by the term arbovirus?

-An arbovirus is an arthropod-borne virus. -An arbovirus is maintained in nature through biological transmission.

Verified exceptions in the use of Koch's postulates

-Some diseases are not caused by microbes. -Some pathogens can cause several disease conditions. - Some diseases have poorly defined etiologies. -Some human diseases have no other known animal host.

Biological transmission

-The pathogen may be injected by the bite of the vector. -The pathogen may enter the host in the vector's feces. -The pathogen may require the vector as a host. -The pathogen reproduces in the vector.

What features of West Nile virus make it an emerging disease of special concern?

-West Nile virus is an arthropod-borne virus transmitted by mosquitoes. -West Nile virus has a high mortality rate in immunosuppressed humans and infects many species of birds in southern Europe, the Mediterranean basin, and North America. - West Nile virus is maintained in nature through biological transmission between susceptible hosts by blood-feeding arthropods.

Match diseases with their transmission

-influenza = droplet infection -malaria = vector -salmonellosis = vehicle transmission -syphilis = direct contact

Diseases spread by droplet infection

-tuberculosis - the common cold -measles -diphtheria

According to the animation, surgical infections account for what percentage of nosocomial infections?

20%

Which of the following would be considered a vector?

A fly carrying disease from fecal matter to food

Which of the following would be an example of disease transmission via indirect contact?

A student sneezes on her test booklet. The instructor grades it and catches her cold.

Which of the following would be considered a fomite?

An infected toy

How might a patient who is not being treated with an antibiotic still be exposed to an antibiotic?

Antibiotics can be used in aerosols, thereby entering the environment.

Which of the following statements is TRUE?

At least one member must benefit in a symbiotic relationship.

The CDC is located in

Atlanta, GA.

What type of nosocomial infection is likely to arise from intravenous catheterizations?

Bacteremia

Which of the following is an example of the symbiotic relationship known as mutualism?

E. coli within the large intestine

Reservoirs of infections are always animate objects.

False

The brain tissue of the birds indicated the possibility of encephalitis. What is encephalitis, and why should this type of infection cause concern among health care professionals?

Encephalitis is an inflammation of the brain tissue. It is a concern to health care professionals because an infection in the brain means the virus has breached protective measures.

MMWR is a publication by the CDC that reports on only emerging diseases.

False

How can health care workers reduce the occurrence of nosocomial infections?

Practice more stringent aseptic techniques

Koch's postulates established criteria for proving that a specific organism causes a specific disease. Which of the following is NOT one of the criteria given by Koch's postulates?

The pathogen must be isolated from inoculated animals and must be different from the original organism.

If mosquitoes are the mode of transmission for West Nile virus, why did the students in Bill's virology class focus on finding the virus in the dead birds rather than collecting mosquitoes to examine?

The students tried to isolate and identify West Nile virus from birds because they are an amplifying host for the virus, making it more likely that the virus can be isolated from these animals.

Transient microbiota differ from normal microbiota in that transient microbiota

are present for a relatively short time.

Which of the following diseases is NOT spread by droplet infection?

botulism

When aerosols containing pathogens spread disease from a distance of less than one meter, it is considered

contact transmission.

A researcher has performed a prospective study on a disease. To which specific kind of epidemiological study is this referring?

descriptive

A cold transmitted by a facial tissue is an example of

fomite

If a prodromal period exists for a certain disease, it should occur prior to

illness

A disease in which the causative agent remains inactive for a time before producing symptoms is referred to as

latent

Focal infections initially start out as

local infections.

A commensal bacterium

may also be an opportunistic pathogen.

The major significance of Robert Koch's work is that

microorganisms cause disease.

Which of the following definitions is INCORRECT?

secondary infection: a long-lasting illness

Which of the following is classified as a latent disease?

shingles