Bed bugs will readily move between units in multi-occupancy settings such as hotels, apartments, hospitals, dormitories etc. As a result, bed bug management efforts in multi-occupancy structures should that are limited to the infested unit only are often prone to failure. Often property or facility managers are reluctant to expand the bed bug management effort to other units whose occupants have not yet complained about bed bugs. By notifying other occupants of the facility there is the risk of creating alarm and panic among residents not to mention the damage that could be caused to the reputation of the facility. Notifying occupants of surrounding units is a sensitive and sometimes difficult proposition however; the reality is that failure to do so end up being very costly in the long run.
One or more of the surrounding units may have well established infestations that have not been reported by the occupants. In situations like this it will be difficult, if not impossible, to eliminate bed bugs in a unit if one or more of the surrounding units are serving as primary source and are not also addressed.
Another reason to investigate the surrounding units is so that you can identify bed bug infestations that may exist at low levels and have not yet been identified by the occupants of the unit. It is not uncommon for people to suffer from a bed bug infestation for several months or more before they finally realize that they have a problem with bed bugs (see also - Early Detection of Bed Bugs ). If not identified, these low level populations may become very well established and prove to be much more difficult to control had they been identified sooner.
Even if no evidence of bed bugs is found in any of the units that are surrounding the infested unit, the risk of infestation of the surrounding units will continue, and may even increase until the infestation in the neighboring unit has been eliminated. As a result, continued inspection of surrounding units is advised until the original infestation has been eliminated.
One pro-active measure that can be considered is the installation of a mattress and box spring encasements for the beds in surrounding units. A proper encasement can serve as an early detection tool (see also Early Detection of Bed Bugs or Mattress and Box Spring Encasements) as well as prevent the mattress and box spring from becoming infested. 
