Cutaneous Leishmaniasis

How cutaneous leishmaniasis spreads

Leishmania parasites live in animals such as rodents, dogs and in some places humans. Female sand flies, which are smaller than mosquitoes, silent and active from dusk to dawn, pick up parasites when they feed and pass them on with their next bite. The parasites multiply inside immune cells in the skin, causing a slowly enlarging sore.

It is not spread from person to person by touch. Rare routes include shared needles, blood transfusion and from mother to baby.

Cutaneous leishmaniasis is the most common form of leishmaniasis, with an estimated 600,000 to 1 million new cases a year worldwide. Travelers, soldiers, aid workers, ecotourists and people who work in forests are at risk.

Old World and New World types

Symptoms

1. A small red bump appears at the bite site, usually 2 weeks to 2 months after the bite, sometimes later.
2. Over weeks it enlarges into a nodule or plaque.
3. The center often breaks down into an ulcer with a raised, firm, reddish border and a crust, looking like a volcano crater.
4. Sores are usually painless unless infected by bacteria. They are typically on exposed skin: face, ears, forearms, hands and lower legs.

Other features:

• Several sores from several bites
• Small satellite lumps around the sore, or a chain of lumps along the lymph channel (this pattern can mimic sporotrichosis)
• Swollen lymph nodes near the sore

Mucosal leishmaniasis

In a small proportion of people infected with certain New World species, parasites later spread to the lining of the nose, mouth and throat, sometimes years after the skin sore healed. Symptoms include a constantly blocked or bleeding nose and sores in the nose or mouth. Untreated, it can destroy the nasal septum and palate. This is why New World infections usually get full treatment.

Diagnosis

The sore can look like other skin ulcers, infections with atypical mycobacteria, fungal infections, or skin cancers such as basal cell carcinoma. Travel history is the key clue. Tests use material from the raised edge of the sore:

• Skin scraping, aspirate or punch biopsy, examined under a microscope for the parasites.
• PCR testing, the most sensitive method, which also identifies the species. The species guides treatment.
• Culture, done in specialized labs.

In the US, the CDC provides reference testing and advice for doctors.

Treatment

Choice depends on the species, number, size and location of the sores, and the patient's immune system.

Local treatment (simple sores)

For small Old World sores in places where they are not cosmetically important:

• Cryotherapy: freezing with liquid nitrogen, repeated every few weeks.
• Thermotherapy: controlled heat applied to the sore.
• Paromomycin cream.
• Injection of an antimony medicine directly into the sore.
• Watchful waiting in selected cases, since many heal without treatment.

Systemic treatment (complex sores)

Used for New World species with mucosal risk, large or many sores, sores on the face, hands, feet or joints, spread along lymph channels, or a weakened immune system:

• Miltefosine tablets (not used in pregnancy)
• Antimony compounds or liposomal amphotericin B given by injection or IV
• Azole antifungal tablets for some species

Treatment is usually led by an infectious disease or travel medicine specialist.

Outlook

Untreated sores usually heal within 3 to 18 months, depending on species, leaving a flat or sunken scar that may be disfiguring on the face. Treatment shortens healing and reduces scarring. After healing, people are generally protected against the same species. People treated for New World infections should report any nasal symptoms in the following years.

Prevention

There is no vaccine or preventive medicine. In endemic areas:

• Avoid outdoor activity from dusk to dawn, when sand flies bite.
• Wear long sleeves and pants and use insect repellent with DEET on exposed skin.
• Sleep in screened or air-conditioned rooms. Use fine-mesh, insecticide-treated bed nets, because sand flies can pass through standard mosquito nets.
• Spray clothing and nets with permethrin.

Frequently asked questions

What does cutaneous leishmaniasis look like?

It starts as a small red bump that slowly grows over weeks into a painless sore or ulcer with a raised, firm border and a crusted center, like a small crater. It usually appears on exposed skin such as the face, arms or legs, weeks to months after sand fly bites.

Is cutaneous leishmaniasis contagious?

No, not by ordinary contact. It spreads through the bite of an infected sand fly. Very rarely, it is passed through shared needles, blood transfusions or from mother to baby. Touching the sore does not spread it to others.

Does cutaneous leishmaniasis go away on its own?

Many sores, especially Old World types, heal on their own within months to about a year and a half, but they usually leave a scar. Some New World species can later spread to the nose and mouth, so they are usually treated even if the sore heals.

How is cutaneous leishmaniasis treated?

Small, simple sores can be frozen, heated, treated with paromomycin cream or injected with medicine. Larger, multiple or high-risk sores are treated with miltefosine tablets or injected antimony or amphotericin B. The species and location of the sore guide the choice.

Can you get leishmaniasis in the United States?

It is rare, but a small number of cases have been acquired in south Texas and southern Oklahoma. Most US cases are in travelers, military personnel and immigrants who were infected in Latin America, the Middle East, Africa or Asia.