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

1. Identify the symptoms and pathogens involved: The patient was hospitalized with dehydration, and V. cholerae and Plesiomonas shigelloides were isolated.
2. Consider the epidemiological clues: The patient did not travel outside the U.S. or consume raw shellfish, but attended a party where others also fell ill.
3. Analyze the food items consumed: Everyone at the party ate crabs and rice pudding with coconut milk. Crabs were also served at a second party where another person experienced mild diarrhea.
4. Evaluate the antibody evidence: Two people from the first party had elevated serum antibodies against Vibrio, indicating exposure to V. cholerae.
5. Determine the most likely source: Given the presence of V. cholerae and the pattern of illness, consider which food item is most likely to be contaminated and responsible for the outbreak.

Key Concepts

Vibrio cholerae

Vibrio cholerae is a gram-negative bacterium that causes cholera, a severe diarrheal disease often linked to contaminated water or food. It produces a potent toxin that leads to rapid fluid loss and dehydration. Understanding its transmission routes and symptoms is crucial for identifying potential sources of infection, especially in outbreaks.

Plesiomonas shigelloides

Plesiomonas shigelloides is a gram-negative bacterium associated with gastrointestinal infections, particularly in individuals who consume contaminated seafood. It can cause diarrhea and is often found in aquatic environments. Recognizing its role in foodborne illnesses helps in determining the source of infections in epidemiological investigations.

Epidemiological Investigation

Epidemiological investigation involves studying the distribution and determinants of health-related states in populations. In this case, it includes tracing the source of infection through patient history, food consumption, and symptom patterns. This process is essential for identifying outbreaks and implementing public health measures to prevent further cases.