How do fleas harm an animal? - briefly
Fleas pierce the skin to ingest blood, leading to anemia, intense itching, and the transmission of parasites and bacterial diseases. Heavy infestations can provoke allergic dermatitis and secondary skin infections.
How do fleas harm an animal? - in detail
Fleas are hematophagous ectoparasites that affect animals through several direct and indirect mechanisms.
-
Skin irritation and inflammation – Mouthparts penetrate the epidermis, causing puncture wounds that trigger itching, scratching, and localized erythema. Repeated trauma leads to thickened, crusted lesions known as flea allergy dermatitis in sensitized hosts.
-
Allergic response – Salivary proteins act as allergens; IgE‑mediated hypersensitivity produces intense pruritus, edema, and secondary excoriation. Chronic scratching can result in alopecia and ulcerated plaques.
-
Blood loss – Each adult consumes 0.5–1 µL of blood per feeding. Heavy infestations may remove 5–10 % of total blood volume daily, precipitating hypoproteinemia and, in small or young animals, severe anemia.
-
Pathogen transmission – Fleas serve as vectors for bacteria (e.g., Yersinia pestis, Bartonella henselae), protozoa (Dipylidium caninum), and viruses. Inoculation occurs during feeding or through fecal contamination of bite sites, leading to systemic infections such as plague, murine typhus, or tapeworm disease.
-
Secondary bacterial infection – Scratching creates breaches in the epidermal barrier, allowing opportunistic skin flora to invade. Common agents include Staphylococcus spp. and Streptococcus spp., which can progress to cellulitis or septicemia if untreated.
-
Stress and immune modulation – Persistent irritation elevates cortisol levels, suppressing immune function and reducing the animal’s ability to resist concurrent diseases. Chronic stress also impairs growth and reproductive performance.
-
Environmental contamination – Flea feces contain digested blood and can contaminate bedding, leading to dermatitis from allergic reactions to flea droppings and facilitating the spread of flea-borne pathogens within a population.
Collectively, these effects compromise skin integrity, diminish hematologic status, and increase susceptibility to infectious diseases, ultimately reducing the overall health and welfare of the infested animal.