pathogen smaller than bacteria

例句：

1. 1.The researcher found a new pathogen that can cause the disease.
   研究人员发现了一种能引起疾病的新病原体。
2. 2. Pathogens are responsible for many diseases in humans and animals.
   病原体是人类和动物许多疾病的原因。
3. 3.The pathogen is spread through contaminated food or water.
   病原体通过受污染的食物或水传播。