Perhaps you should try some spelling variations:
"infections diseases" » "infectious disease", "infection disease", "infective diseases", "infectious diseases", "infection diseases", "infections cases"
"infections disease" » "infectious disease", "infection disease", "infections case"
"infection diseases" » "infectious disease"

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: (((("infections diseases") OR ((("infections disease") OR ("infection diseases"))))) OR ("infectious diseases")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"infections diseases\") or (((\"infections disease\") OR (\"infection diseases\"))))) or (\"infectious diseases\"))".
• Removing quotes may allow a broader search: (((( infections diseases ) or ((( infections disease ) OR ( infection diseases ))))) or ( infectious diseases )).
• Adding a wildcard symbol may retrieve word variants: (((("infections diseases") or ((("infections disease") OR ("infection diseases"))))) or ("infectious diseases"))*.