Why do fleas bite some people? - briefly
Fleas preferentially target individuals who emit greater amounts of carbon dioxide, body heat, and specific skin compounds, which signal a suitable host. People with heightened immune sensitivity often show more pronounced reactions to the bites.
Why do fleas bite some people? - in detail
Fleas locate a host by sensing carbon dioxide, body heat, vibrations, and specific skin odors. Individuals who emit higher levels of these cues become more attractive, prompting the insects to attach and feed.
Blood‑type antigens, particularly type B, have been linked to increased flea interest; the corresponding surface markers appear in sweat and skin secretions, providing a chemical signature that the parasites recognize.
The composition of skin microbiota influences the volatile compounds released from the body. Certain bacterial strains produce metabolites that mimic flea attractants, making some people more likely to be targeted.
Genetic factors affect the density of skin receptors that detect temperature and moisture. People with heightened sensitivity generate stronger thermal gradients, which fleas can follow more easily.
Allergic hypersensitivity also plays a role. When a bite occurs, the immune system releases histamine, causing inflammation and itching. Repeated exposure can amplify the reaction, leading to a perception that the person is bitten more often, even if the actual feeding frequency is unchanged.
Environmental conditions modify risk. Warm, humid climates accelerate flea metabolism, increasing the frequency of feeding attempts. Clothing that exposes more skin surface or is made of natural fibers retains heat and moisture, creating a favorable microenvironment for the parasites.
Flea species differ in host preference. The cat flea (Ctenocephalides felis) and dog flea (Ctenocephalides canis) are opportunistic but show a slight bias toward mammals with certain body‑temperature ranges and grooming habits.
In summary, the likelihood of being bitten depends on a combination of physiological signals (CO₂, heat, odor), blood‑type and skin‑microbe profiles, genetic predisposition, immune response, and external factors such as climate and clothing. Each element contributes to why some individuals experience more flea feeding events than others.