Chlamydophila psittaci infections in humans most commonly result after exposure to

• A. Amphibians
• B. Arthropods
• C. Avians
• D. Mammalians

Answer: (C)

Chlamydophila psittaci is a bird-associated bacterium that causes psittacosis in humans. People most commonly become infected by inhaling aerosols from infected birds, such as dried bird droppings, secretions, or feather dust from psittacine or other avian species kept in aviaries, pet birds, or poultry environments. Because birds are the main reservoir and shed the organism into the environment, exposure to avians is the typical route of human infection. In contrast, amphibians, arthropods, or mammals are not common sources for transmitting this particular pathogen to people.