Perhaps you should try some spelling variations:
complicated diseases » complicated cases, complex diseases, complicated case
mediated diseases » related diseases, medical diseases, related disease
communicable » communicate

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: (( communicable diseases ) OR ((( complicated diseases ) OR ( mediated diseases )))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( communicable diseases ) or ((( complicated diseases ) OR ( mediated diseases ))))".
• Adding a wildcard symbol may retrieve word variants: (( communicable diseases ) or ((( complicated diseases ) OR ( mediated diseases ))))*.