do chiggers leave fungus or bacteria?

Answer 1

Contrary to popular belief, chiggers do not enter your body. They pierce the skin, suck out some of your vital juices, and drop off. They are very small, they don't drink that much.

The "saliva" they leave behind causes moderate to severe itching for several days. I am unaware of fungal infections as a consequence of chigger bites. Theoretically, a chigger could transmit an infection from its bite, but more likely any skin infection arises from scratching with dirty fingernails of the human variety.