Perhaps you should try some spelling variations:
"communicate disabled" » "communicate discover", "communicate listen", "communicated disease"
"complicated diseases" » "complicated cases", "complex diseases", "mediated diseases"
"tropical diseases" » "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 ((("complicated diseases") OR ((("medical diseases") OR ("tropical diseases")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"communicate disabled\") or (\"communicable diseases\"))) or (((\"complicated diseases\") or (((\"medical diseases\") OR (\"tropical diseases\"))))))".
• Removing quotes may allow a broader search: (((( communicate disabled ) or ( communicable diseases ))) or ((( complicated diseases ) or ((( medical diseases ) OR ( tropical diseases )))))).
• Adding a wildcard symbol may retrieve word variants: (((("communicate disabled") or ("communicable diseases"))) or ((("complicated diseases") or ((("medical diseases") OR ("tropical diseases"))))))*.