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