1
Crab Apple Valley Communicable Outbreak Scenario
Western Governors University
D028
2
Crab Apple Valley Communicable Outbreak Scenario
Describe the key components of the case definition for this outbreak scenario. Every case
definition has two criteria: probable and suspect. Every case definition has three key factors:
clinical manifestations, diagnostic or laboratory results, and distribution, in terms of person,
place and time. A case definition is how an epidemiologist decides what a case is and what to
count. It is a set of standard criteria used to classify, and ensure equal comparison of data. For
notifiable diseases on a national level, case definitions are standardized and revised as needed.
For local outbreaks, the definition is tailored to the local area’s situation, such as available
testing facilities, and the limited scope of the surveillance regarding time, person, and place
(Centers for Disease Control & Prevention, 2011).
In the case of Crab Apple Valley (CAV), the case definition is standardized to suit the
local surveillance of the outbreak. The definition states, that individuals will be considered as
suspect case if positive contact with known exposure on or after August 1st at the Crab Apple
Valley farmer’s markets or the community hospital exhibit fever with or without painful, swollen
,lymph nodes, chills, cough, and weakness. In short, patients are suspected cases if they share
clinical manifestations, if they were at a common location and time, exposed to a common
person with the disease. Once they are tested, and they are positive, then we say it is a probable
case.
There are ten outbreak investigation steps used in this scenario (Western Governors
University, n.d.). They are as follows:
1. Identify a surveillance team. Ideally, the team is proactively assembled, before an
outbreak occurs. It is also idea to gather individuals who have expertise to
investigate an outbreak specific to what appears to be the symptoms and
, 3
differentials (Cantey & Gottesfeld, n.d.). The outbreak team consists of
investigation members and support team members. Investigation members
represent public information, pharmacy, purchasing, epidemiologists, statistician,
leadership, laboratory, public health liaisons, nursing, and physicians (Western
Governors University, n.d.).
2. Establish the existence of an outbreak. An outbreak is an increase in the frequency
of a disease above the usual rate in a specific population or geographical area
(Western Governors University, n.d.). In Crab Apple Valley the first appearance
of symptoms and disease was on August 1, when Jack felt pain in his lymph
nodes, dyspnea, and productive cough. On August 4, one day after Jack was taken
to the hospital, EMS and hospital employees reported similar symptoms.
3. Verify diagnosis. Diagnosis is made by taking samples from the patient,
especially blood or part of a swollen lymph gland, and submitting them for
laboratory testing (Centers for Disease Control & Prevention, 2011). In the case
of CAV, we check with the communicable diseases branch of the public health
agency (Cantey & Gottesfeld, n.d.). What are the clinical manifestations?
Symptoms of the CAV suspected cases are reports of the following after August
1: fever over 38 degrees Celsius, tender and swollen lymph nodes, weakness,
chills. The diagnosis should be confirmed based on symptoms, differentials, and
lab data. Chest x-rays showed increased markings bilaterally. Bacteriological
culture for Rapid diagnostic test of buboes and sputum for Yersinia pestis (F1)
antigen.
Crab Apple Valley Communicable Outbreak Scenario
Western Governors University
D028
2
Crab Apple Valley Communicable Outbreak Scenario
Describe the key components of the case definition for this outbreak scenario. Every case
definition has two criteria: probable and suspect. Every case definition has three key factors:
clinical manifestations, diagnostic or laboratory results, and distribution, in terms of person,
place and time. A case definition is how an epidemiologist decides what a case is and what to
count. It is a set of standard criteria used to classify, and ensure equal comparison of data. For
notifiable diseases on a national level, case definitions are standardized and revised as needed.
For local outbreaks, the definition is tailored to the local area’s situation, such as available
testing facilities, and the limited scope of the surveillance regarding time, person, and place
(Centers for Disease Control & Prevention, 2011).
In the case of Crab Apple Valley (CAV), the case definition is standardized to suit the
local surveillance of the outbreak. The definition states, that individuals will be considered as
suspect case if positive contact with known exposure on or after August 1st at the Crab Apple
Valley farmer’s markets or the community hospital exhibit fever with or without painful, swollen
,lymph nodes, chills, cough, and weakness. In short, patients are suspected cases if they share
clinical manifestations, if they were at a common location and time, exposed to a common
person with the disease. Once they are tested, and they are positive, then we say it is a probable
case.
There are ten outbreak investigation steps used in this scenario (Western Governors
University, n.d.). They are as follows:
1. Identify a surveillance team. Ideally, the team is proactively assembled, before an
outbreak occurs. It is also idea to gather individuals who have expertise to
investigate an outbreak specific to what appears to be the symptoms and
, 3
differentials (Cantey & Gottesfeld, n.d.). The outbreak team consists of
investigation members and support team members. Investigation members
represent public information, pharmacy, purchasing, epidemiologists, statistician,
leadership, laboratory, public health liaisons, nursing, and physicians (Western
Governors University, n.d.).
2. Establish the existence of an outbreak. An outbreak is an increase in the frequency
of a disease above the usual rate in a specific population or geographical area
(Western Governors University, n.d.). In Crab Apple Valley the first appearance
of symptoms and disease was on August 1, when Jack felt pain in his lymph
nodes, dyspnea, and productive cough. On August 4, one day after Jack was taken
to the hospital, EMS and hospital employees reported similar symptoms.
3. Verify diagnosis. Diagnosis is made by taking samples from the patient,
especially blood or part of a swollen lymph gland, and submitting them for
laboratory testing (Centers for Disease Control & Prevention, 2011). In the case
of CAV, we check with the communicable diseases branch of the public health
agency (Cantey & Gottesfeld, n.d.). What are the clinical manifestations?
Symptoms of the CAV suspected cases are reports of the following after August
1: fever over 38 degrees Celsius, tender and swollen lymph nodes, weakness,
chills. The diagnosis should be confirmed based on symptoms, differentials, and
lab data. Chest x-rays showed increased markings bilaterally. Bacteriological
culture for Rapid diagnostic test of buboes and sputum for Yersinia pestis (F1)
antigen.
