What is the disease caused by lice called, and what are its symptoms?

What Are Lice?

Types of Lice

Lice are obligate ectoparasites that cause the condition known as «pediculosis». The condition manifests through cutaneous irritation and secondary complications.

Head lice (Pediculus humanus capitis): inhabit scalp hair, lay eggs (nits) on hair shafts, spread by direct head‑to‑head contact.
Body lice (Pediculus humanus corporis): reside in clothing seams, move to skin to feed, associated with poor hygiene and crowded living conditions.
Pubic lice (Pthirus pubis): colonize the coarse hair of the genital region, transmission occurs primarily through sexual contact.
Crab lice (Pthirus pubis variant): occasionally infest eyebrows, eyelashes, or facial hair, sharing the same species as pubic lice.

Symptoms of lice infestation include intense pruritus, erythema, and the presence of viable nits attached to hair or clothing fibers. Repeated scratching may lead to excoriations, bacterial superinfection, and localized lymphadenopathy. Body lice can transmit bacterial pathogens such as Rickettsia prowazekii and Borrelia recurrentis, adding systemic manifestations like fever and rash. Pubic lice may cause papular lesions and secondary inflammation in the affected area. Prompt identification of lice type guides appropriate topical or systemic treatment and hygiene measures.

Pediculosis: The Disease Caused by Lice

Pediculosis refers to infestation by lice, ectoparasites that feed on human blood. The condition includes head lice (Pediculus humanus capitis), body lice (Pediculus humanus corporis), and pubic lice (Pthirus pubis). Infestation occurs when viable lice or nits contact the host’s hair or clothing and establish a feeding site.

Transmission typically follows direct head‑to‑head contact, sharing of personal items such as combs, hats, or bedding, and, for body lice, prolonged use of contaminated clothing. Poor hygiene and crowded living conditions increase risk.

Typical manifestations include:

Persistent pruritus, especially at the scalp, neck, or genital area
Visible nits attached to hair shafts or clothing fibers
Small, mobile insects moving near the skin surface
Red or excoriated lesions resulting from scratching
Secondary bacterial infection of skin lesions in severe cases

Complications may involve impetigo, cellulitis, or, rarely, systemic reactions such as allergic dermatitis. Prompt identification and eradication of lice, combined with cleaning of personal items, prevent recurrence and limit spread.

Common Symptoms of Pediculosis

Itching and Irritation

Pediculosis, the medical term for infestation by lice, triggers a characteristic skin reaction. The parasite’s saliva contains proteins that provoke an immune response, leading to intense pruritus. Persistent scratching damages the epidermis, creating secondary lesions and increasing the risk of bacterial infection.

Key manifestations of the itching and irritation include:

Localized redness surrounding the bite sites
Small papules or wheals that develop after feeding
Swelling of the scalp or affected body region
Secondary excoriations resulting from repeated scratching

Effective management requires prompt removal of the insects, topical or oral pediculicides, and measures to soothe the cutaneous response, such as antihistamine creams or soothing lotions, to reduce discomfort and prevent complications.

Visual Signs

The condition produced by lice infestation is medically termed pediculosis. It manifests on the scalp, body hair, or clothing, depending on the species involved. Visual examination reveals distinct indicators that differentiate it from other dermatological disorders.

Small, elongated insects approximately 2–4 mm in length, often visible moving among hair shafts.
Oval, whitish‑yellow nits firmly attached to the base of hair strands, resistant to removal by simple brushing.
Red or pink papules where lice bite, frequently accompanied by excoriation from scratching.
Scalp or skin areas displaying localized erythema, sometimes forming a halo around the bite site.
Presence of crusted debris or “gray‑ish” material resulting from dried blood and saliva.

Other Potential Symptoms

Pediculosis, the medical term for infestation by lice, can present a range of manifestations beyond the classic pruritus and localized rash.

Additional clinical signs may include:

Erythematous papules or pustules resulting from scratching and secondary bacterial infection;
Hyperpigmentation or post‑inflammatory discoloration at sites of chronic irritation;
Regional lymphadenopathy, particularly in the groin or axillary nodes, reflecting immune response;
Anemia or iron‑deficiency symptoms when infestation is heavy and blood loss from feeding is sustained;
Sleep disruption caused by nocturnal activity of head lice, leading to fatigue and reduced concentration;
Irritability or behavioral changes in children, often linked to persistent discomfort and sleep loss;
Dermatitis secondary to allergic reaction to lice saliva or excrement, presenting as widespread eczematous patches;
Secondary skin infections such as impetigo, frequently observed in areas of excoriation.

Recognition of these less obvious presentations assists in comprehensive assessment and timely management of lice‑related disease.

How Pediculosis Spreads

Pediculosis, the medical term for an infestation by head‑lice, spreads primarily through direct head‑to‑head contact. The insects cling to hair shafts and transfer easily when individuals share close proximity for several minutes.

Common transmission routes include:

Physical contact between heads, especially in schools, camps, or households.
Sharing of personal items that contact hair, such as combs, brushes, hats, helmets, headphones, or scarves.
Contact with contaminated bedding, pillows, or upholstered furniture that have recently hosted an infested person.

The life cycle of the louse facilitates rapid spread. Adult females lay eggs (nits) on hair close to the scalp; nits hatch within 7–10 days, releasing mobile nymphs that can crawl to a new host during any of the above interactions. High infestation rates correlate with crowded environments and limited access to hygiene resources.

Diagnosis of Pediculosis

Pediculosis, the medical term for a lice infestation, is identified through direct observation of the scalp or body hair. Diagnosis relies on visual evidence of live insects, nits adhered to hair shafts, or excoriations caused by scratching.

Key diagnostic procedures include:

Manual inspection with a magnifying device to locate adult lice and nits.
Use of a fine‑tooth comb (wet or dry) to collect specimens for examination.
Dermatoscopy or videodermoscopy to enhance visualization of tiny organisms.
Microscopic analysis of collected material to confirm species and developmental stage.
Skin scraping when secondary bacterial infection is suspected, followed by culture.

Typical clinical indicators prompting examination are persistent pruritus, especially at night, and the presence of translucent ovoid structures attached near the hair base. Absence of these signs generally excludes pediculosis, while detection of live lice or viable nits confirms the condition.

Treatment Options for Pediculosis

Over-the-Counter Treatments

Lice infestation, medically termed pediculosis, manifests with intense itching, visible nits attached to hair shafts, and red or inflamed skin lesions where insects feed. Over‑the‑counter (OTC) products address these symptoms by killing lice and facilitating removal of eggs.

Permethrin 1 % lotion: applied to dry hair, left for ten minutes, then rinsed; kills live lice but may not affect all nits.
Pyrethrin‑based shampoos: combined with piperonyl‑butoxide to enhance toxicity; require thorough combing after treatment.
Dimethicone creams: silicone‑based, suffocates lice and nits without neurotoxic action; suitable for sensitive skin.
Malathion 0.5 % lotion: oil‑based formulation, effective against resistant strains; applied for eight hours before washing.
Benzyl alcohol 5 % lotion: non‑neurotoxic, kills lice by asphyxiation; requires a second application after seven days to eradicate newly hatched insects.

Effective use includes following label instructions, repeating treatment according to product guidelines, and employing a fine‑toothed nit comb to eliminate residual eggs. Persistent itching after two treatment cycles may indicate secondary infection, warranting medical evaluation.

Prescription Treatments

The lice‑borne disease, medically termed «pediculosis», manifests primarily as intense scalp itching, erythematous papules, and the presence of live lice or nits attached to hair shafts. Secondary signs include excoriations from scratching and localized inflammation.

Prescription interventions address both the parasites and the inflammatory response. Commonly employed agents include:

Ivermectin 200 µg/kg orally, single dose; repeat after one week if live lice persist.
Permethrin 5 % cream rinse, applied to damp hair for ten minutes; repeat in seven days.
Malathion 0.5 % lotion, left on scalp for eight to twelve hours; a second application after one week.
Spinosad 0.9 % suspension, applied to dry hair for ten minutes; no repeat needed for most cases.
Benzyl alcohol 5 % lotion, applied for ten minutes; contraindicated in children under six months.

Adjunctive measures comprise antihistamines for pruritus relief and topical corticosteroids to reduce inflammatory lesions when severe. Effective treatment requires adherence to dosing schedules and thorough removal of nits through fine‑toothed combing.

Home Remedies and Prevention

Pediculosis, the medical term for an infestation caused by lice, presents with intense scalp itching, visible nits attached to hair shafts, and occasional redness or secondary bacterial infection.

Apply a mixture of equal parts water and white vinegar to the scalp; leave for 10 minutes before combing out nits with a fine-toothed lice comb.
Use a warm oil treatment (olive or coconut oil) to suffocate lice; cover hair with a shower cap for at least one hour, then remove insects by thorough combing.
Sprinkle diatomaceous earth lightly on the scalp and hair; let sit for 15 minutes before rinsing, exploiting its abrasive properties to damage lice exoskeletons.
Wash clothing, bedding, and personal items in hot water (≥ 60 °C) and dry on high heat; heat eliminates both lice and their eggs.

Prevention relies on regular hygiene practices and environmental controls.

Conduct weekly inspections of hair, especially after close contact with others, using a lice comb to detect early infestations.
Encourage the use of personal hair accessories (combs, hats, scarves) that are not shared among individuals.
Maintain clean bedding and towels; replace or launder them frequently, particularly in communal living spaces.
Keep hair tied back or covered during activities where head-to-head contact is likely, reducing the chance of transmission.

Consistent application of these measures reduces the risk of recurrence and limits the spread of pediculosis.

Potential Complications of Untreated Pediculosis

Pediculosis, the infestation of the body by lice, can persist for weeks or months when left untreated. The presence of live insects and their feces on the skin creates a constant source of irritation and inflammation.

Potential complications include:

Secondary bacterial infection of excoriated skin, frequently caused by Staphylococcus aureus or Streptococcus pyogenes, leading to cellulitis or impetigo.
Chronic dermatitis characterized by erythema, papules, and scaling, which may evolve into lichenified plaques.
Iron‑deficiency anemia in severe infestations, especially among children, due to chronic blood loss from repeated bites.
Enlarged regional lymph nodes resulting from persistent immune activation.
Systemic illnesses transmitted by body lice, such as epidemic typhus, trench fever, or relapsing fever, when the vector carries pathogenic bacteria.
Sleep disruption caused by nocturnal feeding activity, contributing to fatigue and reduced cognitive performance.

Untreated pediculosis therefore poses risks that extend beyond superficial discomfort, necessitating timely therapeutic intervention.

Preventing Lice Infestations

Pediculosis, the medical condition resulting from head‑lice infestation, presents with itching, visible nits on hair shafts, and occasional redness of the scalp. Preventing the spread of lice requires systematic actions that eliminate sources of contamination and reduce transmission opportunities.

Regular inspection of hair, especially after group activities, to detect early nymphal stages.
Immediate removal of identified nits using fine‑toothed combs on damp hair.
Restriction of sharing personal items such as hats, hairbrushes, and headphones.
Routine laundering of bedding, clothing, and accessories at temperatures of at least 60 °C or using a sealed bag for 48 hours to kill dormant lice.
Application of preventive shampoos containing dimethicone or other non‑neurotoxic agents, following manufacturer guidelines.
Education of caregivers and educators about recognition of symptoms and prompt reporting procedures.

Environmental control includes vacuuming upholstered furniture and carpeted areas, and disinfecting surfaces with appropriate insecticidal solutions. Consistent implementation of these measures minimizes the risk of infestation and curtails the development of pediculosis. «Prevention is better than cure».