Think about how easily germs can spread from person to person. In ancient Israel, spiritual 'uncleanness' worked in a similar, yet distinct, way.
Leviticus 15 lays out strict rules for dealing with bodily discharges, which were considered sources of uncleanness. Our verse, Leviticus 15:10, highlights two ways uncleanness could spread beyond the person directly affected:
The Reach of a Touch
Anyone who touched something that had been under a person with an issue became unclean. This emphasizes that the impurity wasn't just on the person, but could transfer through contact with their belongings or even the space they occupied.
The Burden of Carrying
Even more so, someone carrying such an item or person became unclean. This implies a greater responsibility and a more direct involvement in transporting the impurity. The act of carrying made the person a conduit for uncleanness, requiring a more thorough cleansing.