It is a common observation that some individuals emerge from a bed bug infestation covered in itchy welts, while others sharing the same space appear entirely unaffected. This disparity often leads to confusion and sometimes doubt about whether bed bugs are truly present. The explanation for this phenomenon lies in a combination of the bed bug’s host-seeking behaviors and the diverse ways human bodies respond to their bites.
Understanding Bed Bug Attraction
Bed bugs locate their hosts primarily through sensory cues. They are strongly drawn to the carbon dioxide (CO2) exhaled by a sleeping person, using it as a primary signal that a blood meal is nearby. Body heat emitted from humans also serves as a significant attractant, guiding the insects to their target. Additionally, certain chemical compounds found on human skin, such as those in sweat and body odors, further help bed bugs pinpoint a host. While there might be subtle variations in the intensity or composition of these attractants from person to person, bed bugs are generally opportunistic feeders and are not selective about blood types. They will feed on any available warm-blooded host.
Variations in Human Skin Response
The visible “bite” from a bed bug is an allergic reaction to its saliva, not from its piercing mouthparts. When a bed bug feeds, it injects saliva containing anesthetic and anticoagulant chemicals into the skin to prevent the host from feeling the bite and to ensure blood flows freely. The human immune system varies significantly in its response to these injected substances. Some individuals experience a strong histamine reaction, which results in the characteristic itchy, red welts, while others may have a delayed or minimal reaction.
A notable percentage of people, between 30% and 60%, show no visible reaction at all. Their immune systems do not mount a noticeable inflammatory response. Repeated exposure to bed bug bites can sometimes lead to a decreased reaction in some individuals, as their bodies become desensitized. Conversely, others might develop increased sensitivity over time. Severe allergic reactions, although rare, can occur, including hives, blisters, or intense itching.
The Reality of “No Bites”
Not showing visible bite marks does not mean a person is not being bitten. These individuals are likely among the population who do not react, or react minimally, to bed bug saliva. This is common in households where some show bites while others do not, despite sharing an infested space.
Other factors, such as a person’s sleeping patterns or their location within an infested bed, can influence the number of bites received, but not whether they are bitten if an infestation is present. Bed bugs prefer to feed undisturbed, so a person who sleeps more might receive more bites. Therefore, relying solely on bite reactions to confirm bed bugs can be misleading. It is important to look for other physical signs, such as tiny dark spots of fecal matter on bedding, shed skins, or the bugs themselves, to accurately identify an infestation.