Question

In nature, Legionella pneumophila is an intracellular parasite of free-living amoeba. The bacterium multiplies within these protists. However, if humans come into contact with water containing these parasitised amoeba, they can inhale aerosols containing L. pneumophila. Once in the lungs, immune cells phagocytose the bacteria, but the bacteria can survive in the immune cells and multiply therein. This ultimately leads to the symptoms of legionellosis (Legionnaire's disease). Which of the following most accurately describes the role of the amoeba in this process?

•   The amoeba is the vector transmitting the bacterium from animals to humans
•   The amoeba serves as the reservoir for the disease
•   The amoeba exerts genetic reassortment for the bacteria
•   The amoeba is the index case
•   The amoeba is a fomite for persistence of the bacteria in the environment
•   The amoeba acts as the vehicle for transmission

Answer 1