what diseases are mouth contracted?

Answer 1

There are a lot of diseases that are contracted through the mouth, particularly enteric diseases that are transmitted fecal-orally.

Some diseases spread fecal-orally include:
Hepatitis A
E. coli
Salmonellosis
Shigellosis
and various parasitic infections like Giardia or visceral larval migrans.

and a whole lot of others. listing them all would take all day. but do some quick research using keywords "fecal-oral disease"