Perhaps you should try some spelling variations:
"communicated diseases" » "communicated disease", "communicable diseases", "communicable disease"
"complicated diseases" » "complicated cases", "complex diseases", "mediated diseases"
"related diseases" » "related disorders"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("communicated diseases") OR ((("complicated diseases") OR ("related diseases")))).
• Removing quotes may allow a broader search: (( communicated diseases ) or ((( complicated diseases ) or ( related diseases )))).
• Adding a wildcard symbol may retrieve word variants: (("communicated diseases") or ((("complicated diseases") or ("related diseases"))))*.