Why do fleas bite some people in an apartment but not others? - briefly
Fleas target hosts that emit more carbon dioxide, body heat, and specific skin chemicals, making those individuals more attractive to the insects. Those whose skin microbiota or blood type produce fewer of these cues typically receive little or no bites.
Why do fleas bite some people in an apartment but not others? - in detail
Fleas locate a host by detecting carbon‑dioxide, body heat, and movement. Individuals who emit higher levels of CO₂ or maintain a warmer skin surface become more attractive. Metabolic rate, body size, and activity level affect these emissions, so a larger or more active person often draws more attention.
Skin chemistry also influences selection. The composition of sweat, sebaceous secretions, and the resident bacterial flora creates unique odor profiles. Certain compounds, such as lactic acid, ammonia, and fatty acids, are known attractants. People whose skin produces greater quantities of these substances experience more bites.
Allergic sensitivity determines whether a bite is noticed. Some hosts develop a pronounced inflammatory response, producing redness, swelling, and itching, whereas others may have a muted reaction that goes unnoticed. The presence or absence of a visible reaction does not reflect the number of bites received.
Clothing and personal habits modify exposure. Loose garments expose more skin surface, while tight or thick fabrics provide a barrier. Frequent bathing reduces surface odor and removes debris that could lure fleas, decreasing the likelihood of contact.
Environmental factors within the dwelling affect flea distribution. Areas with higher humidity and moderate temperature support flea survival and activity. Rooms where pets rest, especially those that shed heavily, accumulate flea eggs and larvae, creating localized hotspots. Residents who spend most of their time away from these zones encounter fewer bites.
The following points summarize the primary determinants:
- Carbon‑dioxide output: larger body mass, higher respiration rate → stronger lure.
- Heat emission: elevated skin temperature → increased attraction.
- Skin odor profile: higher concentrations of lactic acid, ammonia, fatty acids → greater appeal.
- Allergic response: robust immune reaction → visible bite signs; weak reaction → bites may be missed.
- Clothing coverage: extensive coverage → reduced contact; minimal coverage → higher exposure.
- Personal hygiene: regular washing → lower odor cues; infrequent washing → heightened attraction.
- Proximity to pet habitats: time spent near infested bedding or carpets → higher bite risk.
- Micro‑climate: humidity ≥ 60 % and temperature ≈ 20‑25 °C → optimal flea activity.
Understanding these variables clarifies why some occupants suffer frequent bites while others remain largely unaffected, even within the same apartment. Adjusting personal habits, clothing choices, and environmental conditions can shift the balance toward reduced flea contact.