Which of the following statements best explains why many pathogens use the same portal for both entry and exit from the human body?

• A. It is necessary for pathogens to complete their life cycle.
• B. It allows pathogens to avoid detection by the immune system.
• C. It prevents pathogens from causing disease in the host.
• D. It increases the efficiency of transmission to new hosts.

Answer: (D)

Verified step by step guidance

1. Understand the concept of a portal of entry and exit: In microbiology, a portal of entry is the site through which a pathogen enters the host, and a portal of exit is the site through which it leaves to infect new hosts.
2. Recognize that many pathogens use the same portal for both entry and exit because this strategy maximizes their chances of transmission. For example, respiratory pathogens enter and exit through the respiratory tract.
3. Consider the life cycle of pathogens and how using the same portal can streamline their transmission process, making it easier to spread from one host to another.
4. Evaluate why other options are less likely: avoiding immune detection or preventing disease are not primary reasons for using the same portal; rather, the focus is on transmission efficiency.
5. Conclude that the best explanation is that using the same portal for entry and exit increases the efficiency of transmission to new hosts, facilitating the spread of the pathogen.