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