What does a flea feed on when parasitizing a human host? - briefly
Fleas feed on human blood, extracting it from capillaries just beneath the skin. Their piercing‑sucking mouthparts allow them to draw the fluid directly from the host’s circulatory system.
What does a flea feed on when parasitizing a human host? - in detail
Fleas that infest humans obtain nutrition exclusively from the host’s blood. The insect locates a suitable feeding site by sensing heat, carbon‑dioxide, and movement. Once positioned, the flea inserts its serrated, sheath‑like proboscis through the epidermis and into a capillary. Saliva containing anticoagulants, anti‑inflammatory compounds, and enzymes is released to prevent clotting and to facilitate fluid flow. The flea then draws blood into its foregut, where it is stored temporarily in the crop before passing to the midgut for enzymatic digestion. Nutrient absorption occurs primarily in the midgut epithelium; excess fluid is expelled as waste.
Key aspects of the feeding process:
- Detection: thermal and chemical cues guide the flea to a viable spot.
- Penetration: a hardened stylet pierces the skin and reaches a blood vessel.
- Salivation: anticoagulant and anti‑hemostatic proteins keep the blood liquid.
- Ingestion: blood is drawn into the crop and then to the midgut.
- Digestion and absorption: proteases break down proteins; amino acids are absorbed for metabolism and egg production.
- Excretion: excess water and metabolic by‑products are eliminated as feces, often seen as dark specks on bedding.
Adult fleas require multiple blood meals to develop and to lay eggs; each meal provides the protein and lipid reserves necessary for reproduction. The ingestion of human blood also introduces the possibility of pathogen transmission, as fleas can carry bacteria such as Yersinia pestis or parasites that may be introduced into the bloodstream during feeding.