"Wound" - what is it, definition of the term
A wound is a breach of the integumentary barrier, encompassing skin and possibly deeper tissues, resulting from mechanical trauma, chemical exposure, thermal damage, or biological activity such as bites or infestations by ectoparasites like ticks, insects, lice, and fleas.
Detailed information
Injuries produced by ectoparasites such as ticks, insects, lice, and fleas result from mechanical penetration, saliva‑borne enzymes, and secondary bacterial invasion. The initial breach of skin integrity is typically small, but the biological activity of the parasite’s mouthparts and secretions can generate extensive tissue damage.
Causative agents
- Ticks: embed their hypostome, inject anticoagulant proteins, and may transmit spirochetes or rickettsiae.
- Insects (e.g., mosquitoes, sandflies): bite with serrated mandibles, release anticoagulants and irritants, creating localized ulceration.
- Lice: chew epidermal layers, causing micro‑abrasions that become inflamed.
- Fleas: puncture skin with sharp stylets, introduce proteolytic enzymes, and often leave a chain of bite marks.
Pathophysiology The breach introduces foreign proteins that trigger an immediate inflammatory response: vasodilation, leukocyte migration, and cytokine release. In many cases, the parasite’s saliva contains immunomodulatory substances that suppress localized immunity, allowing pathogens to establish infection. Secondary bacterial colonization, commonly by Staphylococcus aureus or Streptococcus pyogenes, may follow, deepening the lesion and increasing the risk of systemic spread.
Clinical presentation
- Redness and swelling surrounding the entry point.
- Central puncture or papule, sometimes surrounded by a clear halo.
- Pruritus or burning sensation, varying with species.
- Possible fever, malaise, or regional lymphadenopathy if infection progresses.
Diagnostic approach
- Visual inspection of the site for characteristic patterns (e.g., tick’s engorged body, flea’s “break‑fast” bite line).
- Laboratory tests when systemic involvement is suspected: complete blood count, inflammatory markers, and pathogen‑specific serology or PCR.
- Microscopic examination of the lesion exudate for bacterial culture if purulence is present.
Management
- Immediate removal of the parasite with sterile tweezers, avoiding crushing the mouthparts.
- Cleansing of the area using antiseptic solution.
- Application of topical antibiotics for superficial bacterial colonization.
- Systemic antibiotics (e.g., doxycycline) when vector‑borne diseases such as Lyme disease or rickettsial infections are indicated.
- Analgesic or anti‑inflammatory agents to control pain and swelling.
- Monitoring for signs of spreading infection; escalation to surgical debridement if necrosis develops.
Prevention