Times and dates of Bob's symptoms of disease: 

• January 7th: Bob is scratched and bitten by a stray dog.  
• January 9th: The stray dog is found dead. Animal control finds that the dog has Yersinia pestis (bubonic plague). 
• January 10th: Bob has fever, chills, and vomiting. 
• January 11th: Bob is hospitalized with diarrhea & has swollen lymph nodes. 
• Doctors find Bob is infected with Yersinia pestis and give him antibiotics. 
• January 21st: Bob's vitals return to normal and he is released from the hospital. 

Identify the incubation period for Bob's case of the bubonic plague:

• A. January 10th-21st.
• B. January 10th-11th.
• C. January 7th-21st.
• D. January 7th-9th.

Answer: (D)

Verified step by step guidance

1. Understand the concept of the incubation period: It is the time interval between exposure to an infectious agent and the appearance of the first symptoms.
2. Identify the date of exposure: Bob was scratched and bitten by the stray dog on January 7th.
3. Identify the date of symptom onset: Bob began showing symptoms such as fever, chills, and vomiting on January 10th.
4. Calculate the incubation period: The incubation period is from the date of exposure (January 7th) to the date of symptom onset (January 10th).
5. Conclude that the correct incubation period for Bob's case of bubonic plague is January 7th-9th, as this is the time between exposure and the first symptoms.