All substances take up the least amount of volume in their (1.) solid phase, a little more volume in their (2.) liquid phase, and the largest amount of volume in their (3.) gas phase. The closer atoms or molecules get to one another, the less volume is occupied by the substance that they comprise.
A large, retrospective series examining human bite wounds in children found that none of the bites manifesting as abrasions became infected, while the rate of infection was much higher in bite wounds that caused punctures or lacerations.
Although bed bug bites themselves aren't harmful to humans, affects of bed bug bites can cause health complications like sleep deprivation and anemia from loss of blood. Although the bites are intrinsically dangerous, the bites are itchy, and often require over-the-counter treatment to relieve the itchiness. Below is an article from Bed Bugs and Beyond detailing the deleterious affects bed bugs can have on your health, and how to relieve the discomfort caused by bed bugs.