Chapter 9

One-third of the world's population is infected with Mycobacterium tuberculosis, the causative agent of tuberculosis. In 2015, there were 10.4 million new cases of tuberculosis out of 7.2 billion susceptible hosts. An estimated 1.8 million infected individuals died from the disease. Calculate the incidence rate of tuberculosis per 100,000 in the population in 2015.

144.4 cases per 100,000

Which of the following would be considered a vector?

A fly carrying disease from fecal matter to food

Which of the following is/are an example of a healthcare-acquired infection? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. A hospitalized patient develops Staphylococcal sepsis after a nurse transmits the pathogen to the patient while changing wound dressing. A nursing home patient develops a urinary tract infection from a contaminated catheter in a nursing home facility. A child develops a low-grade fever after receiving an inactivated influenza vaccine from his pediatrician. A patient develops pneumonia after using a contaminated ventilator at an outpatient care facility.

A hospitalized patient develops Staphylococcal sepsis after a nurse transmits the pathogen to the patient while changing wound dressing. A nursing home patient develops a urinary tract infection from a contaminated catheter in a nursing home facility. A patient develops pneumonia after using a contaminated ventilator at an outpatient care facility.

Infectious disease commonly follows five basic stages. During which stage would a patient not be able to spread the disease?

A patient may spread an infectious, communicable disease during any of the five stages.

Which of the following is/are primary reason(s) why healthcare settings are hot zones for antibiotic-resistant pathogens? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Abundance of susceptible, immunocompromised patients Lack of disease monitoring Extensive use of antibiotics among patients Failure to use universal healthcare precautions

Abundance of susceptible, immunocompromised patients Extensive use of antibiotics among patients

Which of the following is an example of a direct contact transmission?

An individual contracts rabies after being bitten by a rabid raccoon.

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

Your college-aged patient presents to you with infectious mononucleosis. You observe the classic triad of lymphadenopathy, fever, and pharyngitis, which began one-day prior (on August 30th). After reviewing her case history, you observe that your patient may have been exposed to her infected roommate about 6 weeks ago (on July 15th). About 2 weeks ago (on August 15th), the patient developed fatigue, malaise, and myalgia. Based on this history, which period represents the prodromal period?

Between August 15th and August 29th

Which of the following are examples of endogenous sources of transmission?

Candida albicans (pathogenic strain of yeast)

Which of the following is the most common healthcare-acquired infection (HAIs)?

Clostridium difficile infections

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

Contact, vehicle, and vector transmission

Which of the following is not a responsibility of epidemiologists?

Develop antibiotics

Which of the following is/are a role(s) of the public health system? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Developing policy and plans that support good community health Mobilizing health resources to meet needs Monitoring disease within a population Application of Koch's postulates in human models in order to better understand disease

Developing policy and plans that support good community health Mobilizing health resources to meet needs Monitoring disease within a population

Which of the following factors allows for the best chance of disease eradication?

Disease is preventable through vaccination

Which of the following statements correctly describes Dr. Ignaz Semmelweis's contribution to hospital epidemiology?

Dr. Semmelweis demonstrated that handwashing prior to examining patients cut down on the incidence of nosocomial infections.

You had dinner with your friend who was suffering from a severe cold. She sneezed a few times, and now you are worried that she transmitted her cold to you. During which of the five stages of disease would you expect first symptoms to appear?

During the prodromal phase

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

Five

Which of the following statements is true regarding hand washing?

Frequent and proper hand washing should be routinely done by patients and by healthcare workers, both prior to and after interaction.

Which of the following is a common healthcare-acquired infection?

Gastrointestinal infection caused by Clostridium difficile

According to the figure, when were measles the most prevalent in the US?

In the late 50s

Which of the following is not part of the epidemiological triangle?

Incidence rate

Which of the following is a key factor that contributes to reemerging disease?

Increased antibiotic resistance in a well-known pathogen leads to increased incidence rates.

You observe a high proportion of malarial infections in a small village located in Angola. Malaria is caused by the protozoan Plasmodium and is spread through the female Anopheles mosquito, a biological vector for this disease. Which of the following is a basic strategy that would help to break the epidemiological triangle of malaria? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Instructing residents on personal protective measures, such as bed netting and use of DEET repellent Relocation of the entire village to a neighboring village Increasing the availability of anti-bacterial drugs to the community Controlling the biological vector through chemical larvicides

Instructing residents on personal protective measures, such as bed netting and use of DEET repellent Controlling the biological vector through chemical larvicides

Which of the following is a general goal of epidemiology? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Provide individualized treatments for patients afflicted with infectious diseases. Develop antimicrobial drugs to combat infectious diseases. Intervene to protect and improve health in populations. Describe the nature, cause, and extent of new and existing diseases in populations.

Intervene to protect and improve health in populations. Describe the nature, cause, and extent of new and existing diseases in populations.

In many parts of the US, West Nile infections increase during the summer months. What is the reason?

It is transmitted by mosquitos, which are more prevalent during the summer months.

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

January of year three

Eradication of an infectious disease means that there are no longer any cases of it anywhere in the world. Which of the following types of infectious diseases would be the most difficult to eradicate?

Latent infectious diseases

Which of the following is an example of a reemerging disease?

Mumps, once nearly eliminated, has increased in prevalence due to under-vaccination in industrialized countries.

Which of the following would be considered a symptom? Jaundice Rash Fever Nausea

Nausea

Candida albicans is part of our normal oral flora. Under certain conditions, it can overgrow, leading to oral thrush. Typically, infections are seen in individuals who are immunocompromised, such as newborns or individuals who may have recently taken antibacterial medications. This type of pathogen is classified as which of the following?

Opportunistic, endogenous pathogen

The 1918 influenza virus killed more individuals worldwide than World War One. It is estimated that between twenty and forty percent of the world's population across continents had become infected with the virus, leading to 50 million deaths. The 1918 influenza would best be described as which of the following?

Pandemic

_________ is the ability of an infectious agent to cause disease.

Pathogenicity

Which of the following groups of organisms does not have pathogenic members?

Plants

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

Practice more stringent aseptic techniques

Which of the following is the single most important procedure for a healthcare worker to prevent hospital-acquired infections (HAI)?

Proper handwashing

Choose the true statement(s) about ethical issues in epidemiology. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Public health priorities should be based on evidence and not on political agendas. Research-study participants must be willing to sacrifice their personal wellbeing for the common good. To allow for disease eradication, individual rights to forgo vaccination should be surrendered for the common good. Genetic information of a patient should be kept private and should not be used as a basis of discrimination.

Public health priorities should be based on evidence and not on political agendas. To allow for disease eradication, individual rights to forgo vaccination should be surrendered for the common good. Genetic information of a patient should be kept private and should not be used as a basis of discrimination.

Which of the following statement(s) concerning quarantines is/are true? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Quarantines may be performed on either animal and/or human hosts. If the typical incubation period passes without development of symptoms, quarantined individuals are typically released. If disease develops in the quarantined individual, a quarantine may be maintained until the convalescent period. Quarantines are routinely used for diseases with long incubation periods.

Quarantines may be performed on either animal and/or human hosts. If the typical incubation period passes without development of symptoms, quarantined individuals are typically released. If disease develops in the quarantined individual, a quarantine may be maintained until the convalescent period.

Which of the following characteristics of a catheter should be considered, to help minimize the spread of nosocomial infections?

Single-use

Which of the following statements regarding the National Notifiable Diseases Surveillance System is/are true? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. The United States Center for Disease Control and Prevention publishes the Morbidity and Mortality Weekly Report to update health officials and care providers on national health issues. The United States federal government mandates that every state report local disease cases to a national database. Most states within the United States have laws requiring healthcare providers and laboratories to report certain diseases to local and state authorities. International law requires that the United States Center for Disease Control and Prevention shares nationwide disease statistics with the World Health Organization.

The United States Center for Disease Control and Prevention publishes the Morbidity and Mortality Weekly Report to update health officials and care providers on national health issues. Most states within the United States have laws requiring healthcare providers and laboratories to report certain diseases to local and state authorities.

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 of the following is an example of a measure of association?

The infant mortality rate in the United States due to consumption of unpasteurized honey

Which of the following descriptions provides the best definition for mortality rate?

The number of deaths during a specific time period

Which is an example of vehicle disease transmission?

The presence of Listeria on undercooked chicken served for dinner Submit

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.

How can surgeons help to limit nosocomial infections?

They should perform surgeries and invasive procedures only when absolutely necessary.

What is the role of epidemiology?

To learn how to treat and prevent various diseases.

Which of the following disease agents can be identified based on the original form of Koch's postulates?

Tuberculosis, which can be studied in both mice and humans, is caused by the bacterium Mycobacterium tuberculosis.

Your patient comes to you with typical signs of pneumonia: high fever, shortness of breath, and persistent cough. Several tests are performed to determine the causative agent of disease. You observe that you are unable to culture the microbe using standard microbiological media (such as nutrient agar). Furthermore, use of fluorescent probes reveals that the pathogen has a genome composed of stranded RNA. Which of the following microorganisms are you most likely observing?

Virus

You have isolated a suspected pathogen in pure culture from a diseased laboratory animal. You are not sure whether that organism is what is causing the disease. Applying Koch's postulates, what would be the next step to find out more about the organism?

You should introduce it back into a healthy animal model, and the organism should display the same symptoms.

The primary difference between a biological and a mechanical vector is that:

biological vectors play a role in the pathogen's life cycle, whereas a mechanical vector spreads disease without being integral to a pathogen's life cycle.

Patients infected with Herpes simplex virus-1, the causative agent of fever blisters, go through periods of viral inactivity (where no active oral cankers appear) and outbreaks (where fever blisters are present). This type of individual is best defined as a(n) _______________.

chronic carrier

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

contact transmission.

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

endemic.

A double-blind, randomized study is being used to test the effectiveness of a new drug that targets the multi-drug resistant bacterium Clostridium difficile. Infected participants in the study were given either a placebo or the test drug and then monitored for one month for clearance of infection. This type of study can best be characterized as a(n)_________________.

experimental study

During the Ebola outbreak between 2014 and 2016, according to the CDC an estimated 29,000 cases of Ebola were reported. About 12,000 people died. Therefore, the _________ rate was about 41%.

mortality

Infectious mononucleosis is spread through kissing or other close contact between the host and a healthy individual. This is considered _________.

person-to-person transmission

One out of every 1,000 children who contract measles will develop encephalitis. This statistic is a measure of _______.

proportion

The health of the patient

should be the primary concern of the healthcare worker.

Bacillus cereus is naturally found in the soil. B. cereus is known to contaminate rice, which, if undercooked and ingested, can lead to gastroenteritis. In this example, the reservoir for B. cereus is the ________, and the source of infection is the ___________.

soil; rice

Expected prevalence of a disease is

the expected occurrence of a disease based on past observations.

Epidemiological measures are useful tools because:

they help determine which diseases may need greater public health campaign or prevention efforts.

If a patient notices a healthcare worker not following suggested precautions,

they should immediately bring it to the attention of the healthcare worker. Submit

Lyme disease is spread _________.

through biological vectors

HIV-positive mothers can transmit the virus through breastfeeding. This is considered __________ transmission.

vertical

Epidemiology is defined as the study of

where and when a disease occurs, and how it is transmitted.