1. Psittacosis is a bacterial infection that primarily affects birds but can also be transmitted to humans.
鹦鹉热是一种主要影响鸟类，但也可传染给人类的细菌感染。

2. The symptoms of psittacosis in humans can range from mild flu-like symptoms to severe pneumonia.
人类鹦鹉热的症状可以从轻微的类似流感的症状到严重的肺炎。