Which option is NOT a portal of entry?

Which option is NOT a portal of entry?

• A. Inhalation
• B. Migration through tissue
• C. Ingestion
• D. Injection

Answer: (B)

Portals of entry are the routes by which a pathogen first gains access to the body. Inhalation delivers agents into the respiratory tract, ingestion introduces them through the gastrointestinal tract, and injection bypasses protective barriers to deliver organisms directly into tissues or the bloodstream. Migration through tissue, however, describes movement after entry rather than the entry route itself. It’s about dissemination and invasion within the host once the organism is already inside, not about how it initially gets in. So migration through tissue is not a portal of entry.

Portals of entry are the routes by which a pathogen first gains access to the body. Inhalation delivers agents into the respiratory tract, ingestion introduces them through the gastrointestinal tract, and injection bypasses protective barriers to deliver organisms directly into tissues or the bloodstream. Migration through tissue, however, describes movement after entry rather than the entry route itself. It’s about dissemination and invasion within the host once the organism is already inside, not about how it initially gets in. So migration through tissue is not a portal of entry.