When an outbreak of infectious disease is suspected, the first step is to conduct an epidemiologic investigation. This begins withcharacterizing the outbreak by person, place, and timeto establish patterns and trends. This approach, known as descriptive epidemiology, provides critical insights into potential sources and transmission patterns.

Step-by-Step Justification:

Identify Cases and Patterns:

The infection preventionist should analyze patient demographics (person), locations of cases (place), and onset of symptoms (time). This helps in defining the outbreak scope and potential exposure sources​.

Create an Epidemic Curve:

An epidemic curve helps determine whether the outbreak is a point-source or propagated event. This can indicate whether the infection is spreading person-to-person or originating from a common source​.

Compare with Baseline Data:

Reviewing historical data ensures that the observed cases exceed the expected norm, confirming an outbreak​.

Guide Further Investigation:

Establishing basic epidemiologic patterns guides subsequent actions, such as laboratory testing, environmental sampling, and surveillance​.

Why Other Options Are Incorrect:

B. Increase surveillance facility-wide for additional cases:

While enhanced surveillance is important, it should follow the initial characterization of the outbreak. Surveillance without a defined case profile may lead to misclassification and misinterpretation​.

C. Contact the laboratory to confirm stool identification results:

Confirming lab results is essential but comes after defining the outbreak's characteristics. Without an epidemiologic link, testing may yield results that are difficult to interpret​.

D. Form a tentative hypothesis about the potential reservoir for this outbreak:

Hypothesis generation occurs after sufficient epidemiologic data have been collected. Jumping to conclusions without characterization may result in incorrect assumptions and ineffective control measures​.

CBIC Infection Control References:

APIC Text, "Outbreak Investigations," Epidemiology, Surveillance, Performance, and Patient Safety Measures​.

APIC/JCR Infection Prevention and Control Workbook, Chapter 4, Surveillance Program​.

APIC Text, "Investigating Infectious Disease Outbreaks," Guidelines for Epidemic Curve Analysis​.