PUB 540 Oswego Outbreak Investigation

Study Oswego Outbreak Case

The incubation period, source, and transmission

According to the data presented, the average incubation period of the illness was 4 hours. Most illnesses occurred at 12:30 am and beyond, and the supper took place between 6.00 pm and 11.00 pm. The source of the outbreak was ice cream, which had been prepared a day earlier prior to the church supper. The people involved in the preparation were the Petrie sisters. Transmission possibly occurred through oral ingestion, causing the pathogen to pass from the ice cream to human hosts.

Potential Infectious Agents

Bacillus cereus – has an incubation period of 1-8 hours, and symptoms include vomiting and, in some cases, diarrhea and fever.

Staphylococcus aureus – has an incubation period of 30 mins to 8 hours mostly concentrated between 2-4 hours. The symptoms are vomiting and diarrhea.

Why is this considered an outbreak? Discuss the criteria for why it is considered an outbreak

The illness was an outbreak of gastrointestinal illness. An outbreak occurs when the cases of affected people by a particular disease exceed what is normally expected. Classifying cases as outbreaks depends on the disease’s cause and the type and size of existing and previous exposure to the cause. According to CDC, the criteria for an outbreak include cases having a common cause; for example, in the Oswego case, the affected patients attended the same supper where the illness originated (CDC, 2018). Another criterion is the cluster of cases. In this case, the cases are unusually concentrated in a specific area.

Describe the steps required to investigate an outbreak and apply each step to the Oswego event.

The first step is to verify the diagnosis and confirm the outbreak, using baseline surveillance data to determine if the reported cases are unusual. For uncommon pathogens, the verification can occur through laboratory testing (Webber, 2020). In the Oswego case, this was confirmed by a local health officer who reported the case. The officer would need the number of people presenting with the same symptoms and their relationships. The second step is to define a case and case finding, involving characterization of the cases based on place, time, person, and demographic information (Burckhard & Kissling, 2020). The elements needed to do this include the people at the supper, the time they ate supper, and location information. This step was completed by Dr Rubin, who found out that the cases affected people who attended a church supper. This helped to find the exact number of those who reported gastrointestinal illness (46). The third step is to tabulate data, which was done by representing the Oswego cases in a line listing. The details included the age, sex, time of the meal, and time of illness onset for every affected individual. This information helps create an epidemiology curve that can tell the incubation period and transmission patterns.

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The fourth step involves taking control measures to combat further infections. For example, since the source of infection was ice cream, the control measure in the Oswego case was to discard the remaining portion to avoid further cases safely. Understanding the agent and its origin is essential for completing this step (Seventer, 2018). The fifth step is to formulate a test hypothesis to understand the pathogens involved and the mode of transmission. For example, in this case, the suspected pathogen was Bacillus cereus, and the mode of transmission was through food, making it vehicle-borne transmission. The sixth step is the planning and execution of additional studies. In the Oswego case, this might have involved a case-controlled study to test the hypothesis and find further information about the disease. Information needed to attain this includes the laboratory tests of the affected people, a possible source of the pathogen, and people who are not affected (Webber, 2020). The seventh step is to implement the control measures. In this case, the information from the study would be used to develop and implement control strategies, such as safety precautions during food preparations. Understanding the mode of transmission and the pathogen responsible for the illness is useful for the success of this step. The last step is to determine if the outbreak is over. For example, in the Oswego case, the outbreak was over when no more illnesses associated with gastrointestinal disease were reported.

The possible route of transmission for the expected agent

The possible route of transmission is ingestion, which leads to the transfer of the pathogen to humans. Aerosol could have also been a potential route of transmission in the Oswego case since there were over 80 people in the same place. Airborne transmission is common in congested places (Tellier et al., 2019).

Recommended Control Measures

Primary – implement food safety handling measures, especially when preparing large quantities of meals.

Secondary – screen the people who were at the supper but not affected and family members of those who were affected to identify possible cases that might arise.

Tertiary – ensure that all people affected are treated since only 20% of those who got ill visited a physician.

PUB 540 Oswego Outbreak Investigation References

Burckhard, F., & Kissling, E. (2020). Training for Foodborne Outbreak Investigations by Using Structured Learning Experience. Emerg Infect Dis, 26(1), 162–164. https://doi.10.3201/eid2601.190755.

CDC. (2018). Principles of Epidemiology in Public Health Practice, Third Edition. U.S. Department of Health and Human Services.

Seventer, J. M. (2018). Principles of Infectious Diseases: Transmission, Diagnosis, Prevention, and Control. International Encyclopedia of Public Health, 22–39. https://doi.10.1016/B978-0-12-803678-5.00516-6.

Tellier, R., Li, Y., & Cowling, B. (2019). Recognition of aerosol transmission of infectious agents: a commentary. BMC Infect Dis, 19, 101. https://doi.org/10.1186/s12879-019-3707-y.

Webber, R. (2020). Communicable Diseases: A Global Perspective. CABI.

Webber, R. (2020). Investigating an outbreak. In R. Webber, Communicable Diseases: A Global Perspective 6th Edition. CABI.