focus of natural infection

• 自然疫源地

focus of natural infection的用法和样例：

例句

1. As one of the oldest identifiable diseases known to man, plague remains endemic in many natural loci around the world.
   鼠疫作为人所共知的一种最古老可确定的疾病，在世界上许多自然疫源地仍呈地方性流行。
2. Conclusion The findings of the present study imply that the natural foci of human monocytic ehrlichiosis may exist in northwestern Fujian Province.
   结论福建西北部林区可能存在人单核细胞埃立克体病的自然疫源地。