Use the following information to answer questions 6–7.
On September 6, a 6-year-old boy experienced fever, chills, and vomiting. On September 7, the child was hospitalized with diarrhea and swollen lymph nodes under both arms. On September 3, he had been scratched and bitten by a cat. The cat was found dead on September 5, and Y. pestis was isolated from the cat. Chloramphenicol was administered to the child from September 7, when Y. pestis was isolated from his blood. On September 17, the child's temperature returned to normal. On September 22, the child was released from the hospital.


Identify the incubation period for this case of bubonic plague.
a. September 3-5
b. September 3-6
c. September 6-7
d. September 6-17

Verified step by step guidance

1. Identify the date of exposure to the pathogen, which is when the child was scratched and bitten by the cat on September 3.
2. Determine the onset of symptoms, which began on September 6 with fever, chills, and vomiting.
3. The incubation period is the time between exposure to the pathogen and the onset of symptoms.
4. Calculate the time span from the date of exposure (September 3) to the onset of symptoms (September 6).
5. Match the calculated time span with the given options to identify the correct incubation period.

Key Concepts

Incubation Period

The incubation period is the time between exposure to an infectious agent and the onset of symptoms. In the case of bubonic plague, caused by Yersinia pestis, this period typically ranges from 2 to 6 days. Understanding this concept is crucial for determining when symptoms are likely to appear after exposure, which helps in diagnosing and managing the disease.

Bubonic Plague Symptoms

Bubonic plague is characterized by symptoms such as fever, chills, vomiting, and swollen lymph nodes, known as buboes. These symptoms arise as the bacteria multiply and spread in the body. Recognizing these symptoms is essential for identifying the disease and understanding its progression, particularly in the context of the timeline provided in the question.

Transmission of Yersinia pestis

Yersinia pestis is primarily transmitted through bites from infected fleas, but it can also be spread through direct contact with infected animals, such as cats. In this case, the child's exposure to a cat that was later found to be infected is a critical detail. Understanding the transmission routes helps in assessing the risk of infection and the timing of the incubation period.