```html

Zoonotic Cutaneous Leishmaniasis – A Patient‑Friendly Medical Guide

Overview

Zoonotic cutaneous leishmaniasis (ZCL) is a skin infection caused by protozoan parasites of the genus Leishmania that are transmitted to humans through the bite of infected sand flies. The term “zoonotic” indicates that the parasite primarily circulates among wild or domestic animals (most commonly rodents) and only occasionally infects people.

While ZCL can affect anyone who is bitten by an infected sand fly, the disease is most common in rural, arid, or semi‑arid regions where the sand‑fly vector thrives. The World Health Organization (WHO) estimates that there are 700,000–1,000,000 new cases of all forms of cutaneous leishmaniasis each year, with ZCL accounting for roughly 30–40 % of those cases in endemic countries such as Kazakhstan, Iran, Israel, Morocco, Tunisia, and parts of the former Soviet Union.<sup>[1]</sup>

Because the infection is skin‑limited, it is rarely life‑threatening, but the resulting lesions can cause significant scarring, stigma, and functional problems (e.g., facial disfiguration). Early recognition and treatment are essential to minimize tissue damage.

Symptoms

The clinical picture of ZCL is usually confined to the skin, but the appearance can vary widely. Symptoms typically develop weeks to months after the sand‑fly bite.

• Incubation period: 2 weeks to 6 months (average 1–2 months).
• Papule: A small, raised, erythematous bump at the bite site.
• Plaque: The papule may enlarge into a flat‑topped, firm plaque.
• Ulceration: Central necrosis leads to an ulcer with a raised, indurated border. The ulcer often has a "volcano‑like" appearance with a granulating base.
• Crusting and scabbing: The ulcer may dry and form a crust; this can persist for months.
• Number of lesions: Usually 1–3 lesions, but up to 10 may occur, especially in heavily exposed individuals.
• Location: Exposed areas—face, arms, legs, and hands.
• Pain / itching: Most lesions are painless, though they can be itchy or mildly tender.
• Secondary bacterial infection: Redness, increased pain, purulent discharge – indicating superinfection.
• Systemic signs: Generally absent; fever, malaise, or lymphadenopathy are uncommon in ZCL.

In rare cases, especially in immunocompromised patients, lesions can become chronic (>1 year) or disseminated.

Causes and Risk Factors

Etiology

ZCL is caused by Leishmania major (most common) and, less frequently, Leishmania tropica. The parasites live as amastigotes inside macrophages of the mammalian host and as promastigotes within the gut of female phlebotomine sand flies (genus Phlebotomus in the Old World).

Transmission Cycle

1. Infected sand fly bites an animal reservoir (typically a rodent such as Meriones spp. or Psammomys spp.).
2. Promastigotes multiply in the sand‑fly gut.
3. During a subsequent blood meal, the sand fly injects promastigotes into the skin of a human.
4. Parasites invade dermal macrophages, multiply, and cause the characteristic skin lesion.

Risk Factors

• Living or traveling in endemic rural areas with poor housing (cracked walls, earth floors).
• Agricultural, pastoral, or military work that involves outdoor exposure at dusk or night (peak sand‑fly activity).
• Presence of rodent reservoirs close to dwellings.
• Absence of insect‑proofing (screens, bed nets) or use of protective clothing.
• Immunosuppression (e.g., HIV, corticosteroid therapy) – may increase lesion persistence.

Diagnosis

Diagnosis combines clinical suspicion with laboratory confirmation. Early testing improves treatment outcomes.

1. Clinical assessment

• History of travel or residence in an endemic region.
• Typical lesion morphology and evolution.

2. Laboratory tests

• Skin scraping / impression smear: Giemsa‑stained smears examined under microscopy for intracellular amastigotes (“Leishman‑Donovan bodies”). Sensitivity 50–70 %.
• Culture: Inoculation of lesion material into Novy‑MacNeal‑Nicolle (NNN) medium or Schneider’s Drosophila medium; higher sensitivity but requires 1–2 weeks.
• Polymerase chain reaction (PCR): Detects parasite DNA; >90 % sensitivity and can differentiate species—critical for treatment decisions.
• Histopathology: Biopsy showing granulomatous inflammation with amastigotes; useful when other tests are inconclusive.
• Serology: Generally not helpful for cutaneous disease because antibody titers are low.

3. Differential diagnosis

Other conditions that can mimic ZCL include bacterial ulcer, sporotrichosis, cutaneous mycoses, pyoderma gangrenosum, and skin cancer. Laboratory testing helps rule these out.

Treatment Options

Treatment aims to eradicate the parasite, hasten lesion healing, and limit scarring. The choice of therapy depends on lesion size, number, location, patient age, and local drug availability.

1. Systemic antimonials

• Meglumine antimoniate (Glucantime) or Sodium stibogluconate (Pentostam): 20 mg Sb⁵⁺ kg⁻¹ day⁻¹ IV or IM for 20–28 days.
• Considered first‑line by WHO in many endemic countries.
• Side effects: cardiac arrhythmia, pancreatitis, hepatic toxicity; requires baseline ECG and labs.

2. Oral azoles

• Fluconazole (200–400 mg daily) or Itraconazole (200 mg twice daily): 6–12 weeks, especially for smaller lesions (<2 cm) or patients who cannot tolerate antimonials.
• Evidence from randomized trials in Iran and Tunisia shows comparable cure rates (~80 %) with fewer systemic adverse events.<sup>[2]</sup>

3. Oral miltefosine

• Dosage 2.5 mg/kg/day (max 150 mg) divided into two doses for 28 days.
• Effective for L. major and has an oral route, but is teratogenic – contraindicated in pregnancy.

4. Local therapies

• Thermotherapy: Controlled heat (50 °C for 30 seconds) applied directly to the lesion; cure rates 70–90 % for lesions ≤4 cm.
• Intralesional antimonials: 0.5–1 mL of meglumine antimoniate injected into the base of the lesion weekly for 5–10 weeks.
• Topical paromomycin ointment (15 %): Applied twice daily for 20–30 days; useful for small, uncomplicated lesions.

5. Adjunctive measures

• Proper wound care (cleaning, non‑adhesive dressings).
• Management of secondary bacterial infection with appropriate antibiotics.
• Analgesics for discomfort (acetaminophen or ibuprofen).

Choosing a regimen

Guidelines from the CDC and WHO recommend systemic antimonials for multiple or large lesions, while local therapy is acceptable for solitary, small (<2 cm) lesions on non‑cosmetic areas.<sup>[3]</sup>

Living with Zoonotic Cutaneous Leishmaniasis

Wound care

• Gently clean lesions daily with saline or mild soap.
• Apply a sterile, non‑stick dressing; change daily or if soiled.
• Avoid picking or scratching to prevent secondary infection and scarring.

Skin protection

• Use silicone gel sheets or scar‑reduction silicone after the ulcer has healed.
• Apply broad‑spectrum sunscreen (SPF 30+) on healed areas to prevent hyperpigmentation.

Psychosocial support

• Seek counseling or support groups if facial lesions cause anxiety or stigma.
• Consider referral to a dermatologist for cosmetic interventions (laser, surgical excision) after disease resolution.

Follow‑up schedule

• Initial follow‑up 2 weeks after starting therapy to assess response.
• Subsequent visits every 4 weeks until complete re‑epithelialization.
• Long‑term review at 6 months to monitor for relapse or late scarring.

Prevention

Because ZCL is vector‑borne, preventive measures focus on reducing sand‑fly exposure and controlling animal reservoirs.

• Insect protection: Wear long sleeves, long trousers, and socks during dusk–night hours; treat clothing with permethrin.
• Bed nets: Use insecticide‑treated nets, especially in homes without screened windows.
• Housing improvements: Repair cracks in walls, plaster interior surfaces, and install fine‑mesh screens on windows and doors.
• Environmental control: Remove rodent burrows around dwellings; use rodent control programs where feasible.
• Repellents: Apply DEET (20‑30 %) or picaridin on exposed skin; reapply per product directions.
• Travel advice: Travelers to endemic rural regions should seek pre‑travel counseling and consider chemoprophylaxis (none proven, but early medical evaluation of any skin lesion is essential).

Complications

Although ZCL rarely threatens life, untreated or inadequately treated disease can lead to:

• Severe scarring: Disfiguring facial or neck scars that may impair self‑esteem.
• Secondary bacterial infection: Cellulitis, abscess formation, or systemic infection requiring antibiotics.
• Mucocutaneous spread (rare): Extension to mucous membranes causing nasal or oral perforation, more typical of L. braziliensis than ZCL.
• Chronic non‑healing ulcer: Can persist >1 year, leading to functional limitation if over joints.
• Psychological impact: Anxiety, depression, or social isolation due to visible lesions.

When to Seek Emergency Care

---

References:
[1] World Health Organization. Leishmaniasis. 2022. https://www.who.int/news-room/fact-sheets/detail/leishmaniasis
[2] Alvar J. et al. “Cutaneous leishmaniasis: Current status and future directions.” Clin Dermatol. 2021;39(1):25‑42.
[3] Centers for Disease Control and Prevention. “Leishmaniasis – Clinical Guidance.” 2023. https://www.cdc.gov/parasites/leishmaniasis/clinical.html
[4] National Institute of Allergy and Infectious Diseases. “Leishmaniasis Treatment Guidelines.” 2023.
[5] Mayo Clinic. “Cutaneous leishmaniasis.” Updated 2024. https://www.mayoclinic.org/diseases-conditions/cutaneous-leishmaniasis/diagnosis-treatment/drc-20351744

```