Perhaps you should try some spelling variations:
"communicate disabled" » "communicate discover", "communicate listen", "communicated disease"
"communicable diseases" » "communicable disease"
"complex diseases" » "complex disease"
"tropical diseases" » "tropical disease", "topical 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: (((("communicate disabled") OR ("communicable diseases"))) OR ((("complex diseases") OR ("tropical diseases")))).
• Removing quotes may allow a broader search: (((( communicate disabled ) or ( communicable diseases ))) or ((( complex diseases ) or ( tropical diseases )))).
• Adding a wildcard symbol may retrieve word variants: (((("communicate disabled") or ("communicable diseases"))) or ((("complex diseases") or ("tropical diseases"))))*.