This is from Australia but I think it would be same as USA. High risk is considered-
​​Contacts with higher risk exposures have had direct contact with the patient or their bodily fluids.
-percutaneous (e.g. needle stick) or mucous membrane exposure to blood or body fluids of an EVD patient
-direct skin contact exposure to blood or body fluids of an EVD patient without appropriate personal protective equipment (PPE),
-laboratory processing of body fluids of suspected, probable, or confirmed EVD cases without appropriate PPE or standard biosafety precautions, or
-direct contact with a dead body without appropriate PPE
http://www.health.nsw.gov.au/Infectious/controlguideline/Pages/ebola-virus.aspx