Which infection is commonly transmitted through the respiratory route?

Influenza is commonly transmitted through the respiratory route primarily because it spreads when an infected person coughs, sneezes, or talks, releasing respiratory droplets into the air. These droplets can be inhaled by others nearby, facilitating the transmission of the virus. Contact with surfaces contaminated with respiratory droplets can also lead to infection, but the main mode of transmission for influenza is certainly through respiratory pathways.

In contrast, hepatitis primarily spreads through blood and bodily fluids, not respiratory droplets. Staphylococcus aureus, while it can be found in the respiratory tract, is more often associated with skin infections and spreads through direct contact rather than airborne routes. Norovirus, though it can cause respiratory symptoms in some cases, is primarily transmitted through the fecal-oral route and via contaminated food or surfaces. Hence, influenza is the clear choice when considering common respiratory transmission.