Ch. 14 - Principles of Disease and Epidemiology

Tortora - Microbiology: An Introduction 14th Edition

Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook

Tortora 14th Edition

Ch. 14 - Principles of Disease and Epidemiology

Problem 10

Chapter 14, Problem 10

Use the following information to answer questions 8–10.
A Maryland woman was hospitalized with dehydration. V. cholerae and Plesiomonas shigelloides were isolated from the patient, who had neither traveled outside the United States nor eaten raw shellfish during the preceding month. The patient had attended a party before hospitalization. Two other people at the party had acute diarrheal illness and elevated levels of serum antibodies against Vibrio. Everyone at the party ate crabs and rice pudding with coconut milk. Crabs left over from this party were served at a second party. One of the people at the second party had onset of mild diarrhea; specimens from of these people were negative for vibriocidal antibodies.
The source of the disease was
a. Plesiomonas shigelloides.
b. crabs.
c. V. cholerae.
d. coconut milk.
e. rice.

Verified step by step guidance

Step 1: Identify the pathogens isolated from the patient. The problem states that both Vibrio cholerae and Plesiomonas shigelloides were isolated, so these are the potential causative agents.

Step 2: Analyze the epidemiological clues. The patient and two others at the first party had diarrheal illness and elevated serum antibodies against Vibrio, indicating exposure to Vibrio cholerae rather than Plesiomonas shigelloides.

Step 3: Consider the food items consumed at the party. Everyone ate crabs and rice pudding with coconut milk. Since the illness is linked to Vibrio cholerae, which is commonly associated with seafood, crabs are a likely source.

Step 4: Note that leftover crabs were served at a second party, where one person developed mild diarrhea but had no vibriocidal antibodies, suggesting no Vibrio cholerae infection in the second party attendees.

Step 5: Conclude that the most probable source of the disease is the crabs contaminated with Vibrio cholerae, based on the pathogen isolated, antibody evidence, and food exposure history.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Pathogenicity and Transmission of Vibrio cholerae

Vibrio cholerae is a bacterium that causes cholera, characterized by severe diarrhea and dehydration. It is typically transmitted through contaminated water or food, especially seafood. Understanding its pathogenicity and common transmission routes helps identify likely sources in outbreaks.

Role of Vibriocidal Antibodies in Diagnosis

Vibriocidal antibodies are immune proteins produced in response to Vibrio cholerae infection. Elevated serum levels indicate recent or ongoing infection, making them useful markers for confirming exposure and differentiating between infected and non-infected individuals.

Epidemiological Investigation of Foodborne Outbreaks

Epidemiology involves tracing the source and spread of infections by analyzing patient histories, food consumption, and symptom patterns. Identifying common foods and exposure events among affected individuals helps pinpoint the outbreak source and implement control measures.

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An encapsulated bacterium can be virulent because the capsule

a. resists phagocytosis.

b. is an endotoxin.

c. destroys host tissues.

d. kills host cells.

e. has no effect; because many pathogens do not have capsules, capsules do not contribute to virulence.

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Name one fungus and one protozoan that can cause genital system infections. What symptoms would lead you to suspect these infections?

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Put the following in the correct order to describe the pattern of disease: period of convalescence, prodromal period, period of decline, incubation period, period of illness.

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Textbook Question

Use the following information to answer questions 8–10.

A Maryland woman was hospitalized with dehydration. V. cholerae and Plesiomonas shigelloides were isolated from the patient, who had neither traveled outside the United States nor eaten raw shellfish during the preceding month. The patient had attended a party before hospitalization. Two other people at the party had acute diarrheal illness and elevated levels of serum antibodies against Vibrio. Everyone at the party ate crabs and rice pudding with coconut milk. Crabs left over from this party were served at a second party. One of the people at the second party had onset of mild diarrhea; specimens from of these people were negative for vibriocidal antibodies.

This is an example of

a. vehicle transmission.

b. airborne transmission.

c. transmission by fomites.

d. direct contact transmission.

e. healthcare-associated transmission.

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Textbook Question

This microbe is acquired by humans as infants and is essential for good health. Acquiring a closely related strain causes severe stomach cramps, bloody diarrhea, and vomiting. What is the microbe?

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