Which of the following is NOT a normal portal of exit for an infectious disease?

• A. Saliva
• B. Liver
• C. Urine
• D. Feces

Answer: (B)

Verified step by step guidance

1. Understand the concept of 'portal of exit' in infectious diseases: it refers to the route through which a pathogen leaves the host to spread to others.
2. Identify common portals of exit, which typically include bodily fluids and excretions such as saliva, urine, feces, blood, and respiratory droplets.
3. Evaluate each option given: saliva, urine, feces, and liver. Saliva, urine, and feces are all common bodily fluids or excretions that can carry infectious agents out of the body.
4. Recognize that the liver is an internal organ and not a route through which pathogens exit the body; it is involved in metabolism and detoxification but not in the direct release of infectious agents to the external environment.
5. Conclude that the liver is NOT a normal portal of exit for infectious diseases, unlike saliva, urine, and feces.