Perhaps you should try some spelling variations:
"complicated diseases" » "complicated cases", "complex diseases", "mediated diseases"
"communicated disease" » "communicable diseases", "communicate state", "communicated vision"
"communicable disease" » "communicable diseases"

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: (("complicated diseases") OR ((("communicated disease") OR ("communicable disease")))).
• Removing quotes may allow a broader search: (( complicated diseases ) or ((( communicated disease ) or ( communicable disease )))).
• Adding a wildcard symbol may retrieve word variants: (("complicated diseases") or ((("communicated disease") or ("communicable disease"))))*.