"Disease" - what is it, definition of the term
An illness is a disruption of normal biological processes that produces observable signs or symptoms due to internal or external disturbances; ectoparasites such as ticks, bugs, lice, and fleas function as vectors or direct irritants that introduce pathogens or cause tissue injury, thereby generating such pathological conditions.
Detailed information
Ticks transmit a range of bacterial, viral, and protozoan infections. Lyme disease, caused by Borrelia burgdorferi, presents with erythema migrans, fever, headache, and joint pain; early antibiotic therapy reduces the risk of chronic arthritis and neurologic involvement. Rocky Mountain spotted fever, driven by Rickettsia rickettsii, produces a sudden fever, rash that spreads from wrists and ankles, and may progress to vascular injury without prompt doxycycline treatment. Tick‑borne encephalitis, prevalent in Eurasia, leads to meningitis‑like symptoms and can cause long‑term cognitive deficits. Prevention relies on repellents, proper clothing, and prompt removal of attached ticks.
Bedbugs (Cimex lectularius) are primarily a nuisance species; they do not act as vectors for known pathogens. Their bites cause localized erythema, pruritus, and occasional allergic reactions. Secondary skin infections may arise from scratching. Control measures focus on thorough inspection, heat treatment, and integrated pest management to eliminate infestations.
Lice infestations are divided into three types: head lice, body lice, and pubic lice. Body lice (Pediculus humanus corporis) transmit several serious infections, including epidemic typhus (Rickettsia prowazekii), relapsing fever (Borrelia recurrentis), and trench fever (Bartonella quintana). These illnesses manifest with high fever, rash, and severe fatigue; antibiotic regimens such as doxycycline or chloramphenicol are effective when administered early. Head and pubic lice transmit no known pathogens, but their presence can cause intense itching, secondary bacterial infection, and psychosocial distress. Management includes mechanical removal, topical pediculicides, and hygiene measures.
Fleas (Siphonaptera) serve as vectors for several zoonotic infections. The cat flea (Ctenocephalides felis) and the rat flea (Xenopsylla cheopis) transmit Yersinia pestis, the agent of plague, which progresses from bubonic swelling to septicemic or pneumonic forms if untreated. Plague requires immediate administration of streptomycin or gentamicin. Fleas also carry Rickettsia felis, causing flea‑borne spotted fever characterized by fever, headache, and rash; tetracycline antibiotics are the treatment of choice. Effective control includes regular animal grooming, environmental insecticide application, and rodent population management.
Key preventive actions across all vectors