What does the human flea feed on when parasitizing humans? - briefly
The human flea (Pulex irritans) feeds by piercing the skin and sucking the host’s blood. During feeding it may also ingest trace amounts of lymphatic fluid.
What does the human flea feed on when parasitizing humans? - in detail
The human flea (Pulex irritans) is an obligate hematophagous ectoparasite. When it occupies a human host, it obtains nourishment exclusively from the host’s blood. The insect inserts its proboscis into the skin, penetrates the epidermis and reaches dermal capillaries, where it draws a liquid meal rich in erythrocytes, plasma proteins, and dissolved nutrients.
A single feeding episode typically lasts 5–10 minutes and yields 0.2–0.5 µL of blood. The flea may repeat this process several times per day, especially after a period of starvation. Blood ingestion is required for egg production; a female that has consumed at least one full blood meal can develop and lay up to 50 eggs over her lifespan.
While humans constitute the primary source of nourishment during an infestation, the species is not strictly host‑specific. In the absence of human blood, it will opportunistically feed on other mammals such as dogs, cats, rodents, and livestock. However, when humans are available, the flea preferentially selects them due to ease of access and the warmth of the host’s skin.
Feeding induces localized skin reactions: vasodilation, erythema, and pruritus. Repeated bites can lead to papular dermatitis and, in rare cases, allergic sensitization. The flea’s saliva contains anticoagulants and anti‑inflammatory compounds that facilitate blood flow and reduce host detection during the meal.
In summary, the human flea derives all nutritional requirements from the blood of its host, primarily humans, employing a rapid, repeated feeding strategy that supports reproduction and sustains its life cycle.