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