MCB 100 HW 5

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.

A patient with West Nile viral encephalitis asks his nurse practitioner how he could have contracted the disease. The NP explains that the causative virus is carried by infected mosquitoes from birds to people. This is an example of disease transmission through

a biological vector.

An example of a mechanical vector is:

a housefly at a picnic.

Some bacteria secrete chemicals that prevent the phagocytic digestion of a bacterium by interfering with the fusion of _____ to the phagosome.

a lysosome

Hyaluronidase and collagenase both allow bacteria to _____.

invade a host's tissues

The release of lipid A may lead to _____.

fever, blood clotting, inflammation, and shock

How could this epidemic be stopped without firing the worker?

Educate the worker about personal hygiene; use an outhouse or designated bathroom. Instruct him to thoroughly wash his hands with clean soap and water after using the facilities.

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.

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 type of toxin, when secreted, may lead to the disruption of the cells within the gastrointestinal tract?

enterotoxin

In early spring 2009, the CDC reported several dozen cases of novel H1N1 influenza ("swine flu") in the United States. By the end of the year millions of people had been infected. The pattern of novel H1N1 cases in the United States represents a(n) ________ disease.

epidemic

What are the clinical signs and symptoms of typhoid fever? fever and rose-spotted rash How would you classify this abrupt jump in cases of Legionellosis in Louisiana?

epidemic

What are the clinical signs and symptoms of typhoid fever?

fever and rose-spotted rash

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

five

What is the reservoir for this disease organism, Salmonella enterica serotype Typhi?

humans

What do we call the person determined to be the first case of a disease in an outbreak?

index case

The scientific method is a four-step framework for the process of scientific investigation. Scientists have successfully applied the scientific method to address problems and questions for more than a century. The application of the scientific method has helped move science from philosophical debate to an understanding of the world around us based on reproducible facts and phenomena.

observation, formulate, design, scientist

A major difference between exotoxins and endotoxins is that endotoxins are _____.

physically part of the bacterial structure

Bacterial capsules work by _____.

protecting the bacterium from engulfment

Expected prevalence of a disease is

the expected occurrence of a disease based on past observations.

How was this carrier identified?

urine culture

Jerica takes her young son to the pediatrician for regular childhood immunizations. While there, they wait in a room full of sneezing, sniffling, coughing youngsters. Despite making sure that her son stays at least six feet (two meters) from the other children and doesn't touch any play toys in the waiting room, microbes could still spread to her son by

vehicle transmission.

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

endemic

Based on the data supplied, what was the approximate mortality rate for this outbreak?

14%

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.

Why may some bacteria use extracellular enzymes to form blood clots?

Blood clot can hide bacteria from the immune system.

Dr. John Snow's investigation of the cholera epidemic of 1854 most closely matches which approach to epidemiology?

Descriptive

Scientist decides to accept, reject or modify a hypothesis: Dr. Snow concludes a specific well is the source of the cholera cases. Match the terms for disciplines in epidemiology with the most appropriate definition.

Descriptive epidemiology: Observe and collect data concerning a disease. Experimental epidemiology: Design and conduct a test of a hypothesis about a disease. Analytical epidemiology: Make a detailed investigation of data collected concerning a disease.

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.

What additional information would you request from those who survived the disease?

How tall are they and were the misters on when they shopped the produce aisle?

Is Legionellosis contagious?

No. Legionellosis is not contagious.

Drag the description of Dr. Snow actions or activities to the step of the scientific method it most closely fits.

Observation leads to formulation of a question: Observations suggest to Dr. Snow water is involved in cholera. Formulation of a hypothesis to address a question: Observations suggest to Dr. Snow water is involved in cholera. Design and conduct experiments: Not Applicable Collect and analyze data: Dr. Snow collects information about patients' activities prior to becoming ill.

Match the field of epidemiology with the step of the scientific method it most closely fits.

Observation- descriptive Formulation- Experiment Design- nothing Scientist- analytical

A patient is sickened after being infected with Escherichia coli (E. coli) from consuming contaminated lettuce; this disease transmission. is a type of _______________ disease transmission.

Vehicle

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.

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.

What type of epidemiological study is exemplified in this case?

analytical

Virulence factors allow microbes to be pathogens. This means that a bacterium with more virulence factors _____.

can more easily infect hosts and cause disease