Travel
According to the website Medicine Net, bed bugs hide away in luggage, clothing and other personal objects when people travel between hotels. Since many different people bring luggage into the room and sleep in the same bed, hotels are at an especially high risk of bedbug infestations. Bed bugs move by crawling, and so they can quickly infect adjoining rooms.
Used Furniture
Homes and apartments are can be infected with bedbugs when used furniture is introduced into the home. The Harvard School of Public Health warns that used mattresses, bed frames, and items from off the street may be infected with bed bugs. They hide in furniture joints and mattress tufts, among other places.
Empty Apartments
Empty or vacant apartments may be infested with bed bugs. The Harvard School of Public Health explains that bed bugs can live for many months without feeding. They hide behind wallpaper and molding. In addition, these parasites can easily pass through wiring or duct work from one apartment to another.