Final answer:
Acute sinusitis usually starts within a week after an upper respiratory tract infection and lasts under four weeks, often following a common cold and possibly leading to bacterial rhinosinusitis.
Step-by-step explanation:
Acute sinusitis typically begins within 1 week of an upper respiratory tract infection and lasts less than 4 weeks. This condition is one facet of a broader category of illnesses that affect the upper respiratory tract, where viral infections are the most frequent cause. Following such viral infections, a person may experience rhinosinusitis, which is an inflammation of the nasal pathways and sinus cavities.
It is often preceded by the common cold, characterized by symptoms such as a runny nose, congestion, and sore throat. The inflammation in these cases can lead to a secondary bacterial infection due to pathogens like S. pneumoniae, H. influenzae, and M. catarrhalis gaining an opportunity to establish themselves.
The resulting condition, bacterial rhinosinusitis, then typically presents with symptoms lasting up to four weeks but generally resolving on their own with proper care. Understanding the differentiations between symptoms and durations of these infections is essential for appropriate treatment and management.