Why do bedbugs bite one person but not another? - briefly
Bedbugs target hosts whose skin odor, blood type, and body‑heat signatures align with the insects’ sensory preferences, while less appealing cues deter feeding. Genetic variations in immune response can suppress visible bite reactions, giving the impression that some people are not bitten.
Why do bedbugs bite one person but not another? - in detail
Bedbugs select hosts based on a combination of physiological and chemical signals. Individual differences in skin temperature, carbon‑dioxide output, and body odor create distinct attraction gradients. Elevated skin temperature signals a blood‑rich area, while higher carbon‑dioxide emission indicates respiration intensity. These cues vary with metabolic rate, activity level, and body size, making some people more detectable.
The composition of skin microbiota influences volatile organic compounds released from the surface. Certain bacterial strains produce aldehydes and fatty acids that stimulate the insect’s chemoreceptors. Research shows that individuals with a higher proportion of Corynebacterium and Staphylococcus species attract more bites than those dominated by Propionibacterium.
Blood characteristics also affect feeding preference. Blood type, specifically the presence of certain antigens, alters the chemical profile of sweat and plasma. Studies indicate that type O individuals may experience more frequent attacks than type A, although the effect size is modest. Additionally, the concentration of cholesterol, lactic acid, and other metabolites in the blood can enhance palatability for the bug.
Genetic factors modulate immune response to bedbug saliva. Some hosts develop rapid localized swelling and histamine release, deterring further feeding, while others exhibit muted reactions, allowing prolonged blood meals. This variation stems from differences in histamine receptor density and cytokine production.
Previous exposure influences future biting patterns. Repeated contact can sensitize the immune system, leading to stronger reactions that discourage subsequent feeding. Conversely, naïve individuals lacking such sensitization may appear more attractive because the bug encounters fewer defensive responses.
Summarized determinants:
- Thermal signature: higher skin temperature → increased attraction
- Respiratory output: elevated carbon‑dioxide → stronger cue
- Skin microbiome: specific bacterial profiles → distinct odorants
- Blood type and metabolite levels: certain antigens and chemicals → greater palatability
- Immune reactivity: muted histamine response → longer feeding periods
- Prior exposure: lack of sensitization → reduced deterrence
Understanding these factors clarifies why bedbugs preferentially bite some individuals while sparing others.