Final answer:
The infection pattern of small airways with epidemics in winter and spring is frequently caused by viruses, with influenza being a common example. These infections can range from mild to severe and are influenced by seasonal changes in immune defenses. Epidemics like influenza and walking pneumonia are more prevalent during cold seasons due to a variety of factors.
Step-by-step explanation:
Viruses are responsible for the majority of respiratory tract infections, with patterns of infections like influenza becoming more prevalent during the winter and spring months, especially in the northern hemisphere. The infection pattern of small airways with epidemics follows a seasonal trend, where conditions such as the common cold, influenza, and mycoplasma pneumonia (walking pneumonia) can manifest more frequently and with varying degrees of severity. These respiratory infections can range from mild to severe, causing symptoms including fever, chills, and persistent cough, and in more serious cases, can lead to pneumonia.
Influenza, in particular, can cause significant health issues with thousands of deaths annually in the United States. It is characterized by its capability to cause epidemics during winter, with some years witnessing unusually large numbers of cases. Factors contributing to the seasonal variation in infection rates include changes in host defenses like immune cell activity, which can be influenced by the temperature, pollution, and stress.