Bio 211 Chapter 14 Homework

In the sixth segment of the animation, why is the disease epidemic in North America?

The disease occurs at a higher rate than what would normally be expected in this region.

Which is an example of vehicle disease transmission?

The presence of Listeria on undercooked chicken served for dinner

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.

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.

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

Contact, vehicle, and vector transmission

In the last segment of the animation, when does the first epidemic occur?

January of year three

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 communicable disease?

tetanus

Expected prevalence of a disease is

the expected occurrence of a disease based on past observations.

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.

In the last segment of the animation, how many regions of the world experience the pandemic during April of year four?

Five

The yeast Candida albicans does not normally cause disease because of

antagonistic bacteria.

If a disease occurs at a fairly stable rate, it is said to be

endemic.

A rabbit was found to have floppy ear disease, which causes long-ear infections. Its etiology (cause) is unknown. Unknown Microorganism X from the infected rabbit's right ear is successfully isolated and cultured on laboratory growth media. The ear of a healthy laboratory mouse is then inoculated with isolated microorganism, and after a period of time, no disease is observed. Which of the following statements accurately describe(s) the conclusion(s) that can be drawn from this experiment?

-A laboratory mouse might not be an appropriate, susceptible host; an experiment with a laboratory rabbit may be needed. -Microorganism X might not be linked to floppy ear disease, because the inoculated mouse remained healthy.

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

Understanding Koch's Postulates This activity asks you to identify Koch's postulates for determining the etiology of infectious diseases. Which statements accurately describe Koch's postulates?

-The same pathogen must be present in every case of the disease. -The pathogen must be isolated from the diseased host and grown in pure culture. -The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal. -The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

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.

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 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.

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

Bacteremia

Limitations to Koch's Postulates This activity asks you to sort statements that describe the benefits and limitations of using Koch's postulates to determine the etiology of infectious diseases. For each of the following statements, determine whether it describes a benefit or a limitation of Koch's postulates.

Benefit: -laboratory findings provide experimental evident that support the germ theory of disease -healthy, susceptible animals can be used as model organisms for testing many types of infections, thus avoiding the unethical inoculation of healthy human hosts -The steps are designed to systematically link a pathogen to specific infectious disease Limitation: -Different pathogens can produce the same signs and symptoms, making it difficult to determine which microorganism is causing a disease -Some pathogens cause several different diseases, which make it difficult to link on pathogen to one disease using Koch's postulates -Some infectious agents have specific growth requirements that prevent them from being artificially cultured in the laboratory

During a six-month period, 239 cases of pneumonia occurred in a town of 300 people. A clinical case was defined as fever 39°C lasting >2 days with three or more symptoms (i.e., chills, sweats, severe headache, cough, aching muscles/joints, fatigue, or feeling ill). A laboratory-confirmed case was defined as a positive result for antibodies against Coxiella burnetii. Before the outbreak, 2000 sheep were kept northwest of the town. Of the 20 sheep tested from the flock, 15 were positive for C. burnetii antibodies. Wind blew from the northwest, and rainfall was 0.5 cm compared with 7 to 10 cm during each of the previous three years. The etiologic agent of the disease in the situation is

Coxiella burnetii.

Experimental Approaches for Understanding Disease This activity asks you to view Foundation Figure 14.3 and determine the purpose of key components of this experiment. The key components include the diseased or dead animal, the healthy laboratory animal, the microscope, and the growth media. Robert Koch performed experiments to determine the specific microorganisms associated with specific diseases.

Diseased or dead animal- original source of the infectious microbial agent Healthy laboratory animal- organism injected with a potential infectious agent Microscope- tool used to view and identify individual microorganisms Growth media- nutrient-rich environment for isolating and culturing microorganisms

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.

Etiology and Infectious Disease This activity asks you to match each key term related to etiology and infectious disease with its description. Based on the information contained in the introduction, match each of the following concepts with its best description.

Etiology- the study of the cause of a disease Infectious disease- disease directly caused by microorganisms and not by other means, for example, genetic or degenerative diseases Germ theory of disease- this theory states that microorganisms cause infected diseases Koch's postulates- experimental requirements for identifying the agent of an infectious disease

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

Practice more stringent aseptic techniques

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

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

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

contact transmission.

Which of the following definitions is INCORRECT?

epidemic: a disease that is endemic across the world

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.

A commensal bacterium

may also be an opportunistic pathogen.

In which of the following diseases can gender be considered a viable predisposing factor?

urinary tract infections