Leishmaniasis is a complex parasitic disease caused by protozoa of the genus Leishmania, which is transmitted through the bite of infected sandflies. Its manifestations can vary widely, ranging from disfiguring skin ulcers to potentially fatal organ damage. What makes leishmaniasis particularly challenging is its diverse presentation, with distinct forms like cutaneous, mucocutaneous, and visceral leishmaniasis. Each poses unique risks, especially in regions where timely diagnosis and treatment remain inaccessible. Mucocutaneous leishmaniasis affects the mucous membranes, often causing severe tissue destruction.
Leishmaniasis impacts individual health and places a significant burden on healthcare systems in endemic areas, highlighting the importance of early detection and intervention.

What causes Leishmaniasis?

Leishmaniasis is caused by 20 different species of leishmania protozoa.¹
These protozoa enter the human bloodstream through the bite of a vector, sandfly. These sandflies are usually native to Europe, Asia, Africa, and Latin America.
However, as tourism is gaining popularity, these sandflies are able to travel along with humans from their homes in forests to the cities.
These protozoans have been inhabiting the lands for ages. Mummies dating back to 2500 BCE have been shown to have yielded Leishmaniasis donovani DNA.²

How common is it?

According to the World Health Organization (WHO),³ about 700,000 – 1 million new cases of Leishmaniasis occur annually. However, the actual figures must be higher as the majority of infected patients do not develop any symptoms, and only a small fraction of the cases are officially reported to the WHO.

Where is Leishmaniasis Endemic?

It’s endemic in various parts of the world. Based on the geographical distribution of different strains, it is categorized into two main types:

Old World Leishmaniasis:

Prevalent in the Eastern Hemisphere, including:

Parts of Asia
Africa, especially tropical regions and North Africa
Southern Europe
The Middle East

New World Leishmaniasis:

Endemic in the Western Hemisphere, including:

Central America
South America
Some regions of Mexico

While a few cases of cutaneous variant have been reported in the U.S., it remains relatively uncommon here.

How does one become infected with Leishmaniasis?

Protozoans belonging to the Leishmania genus live inside the guts of female Phlebotomine sandflies. Two other sandfly species known to the world are Sergentomyia and Lutzomyia. A female sandfly must bite you to release these protozoa into your bloodstream. Other than humans, 70 other species can also host this parasite.

Image of a parasite that causes leishmaniasis — Image Source: Picryl (CC license)

Types of Leishmaniasis:

There are three major types of Leishmaniasis, which vary in their presentations and severities, namely;

Cutaneous Leishmaniasis (CL)
Mucocutaneous Leishmaniasis (ML)
Visceral Leishmaniasis (VL)

Cutaneous Leishmaniasis (CL):

It is the most common variant and can be exhibited in two forms: localized and diffuse.
The localized forms⁴ can occur anywhere between two to four weeks from the time of the bite. You will see a bunch of papules or raised nodules appear at the site of inoculation. These then coalesce to form a volcanic ulcer, well-circumscribed with raised borders. Healing of the ulcer is generally slow (months to years), and it tends to leave behind a scar.

Diffuse leishmaniasis⁵usually affects the ones with a weakened immune system (HIV-affected individuals are more susceptible here). Here, the primary lesion enlarges to involve larger skin areas. The skin of the face, ear, extensor surfaces, buttocks, and extremities are usually involved. These lesions may also spread over the entire body, resembling lepromatous leprosy. However, they remain non-erosive and non-destructive, though significantly disfiguring.

Image of a man with leishmaniasis — Image Source: Wikipedia (CC license)

Leishmaniasis recidivans⁶ is also a cutaneous variant wherein a lesion may occur years after inoculation. Weakened immunity or skin trauma to the site of the bite may trigger the activation of latent protozoans. These lesions are generally resistant to treatment.

Mucocutaneous Leishmaniasis (ML):

It is a rare variant of Leishmaniasis and, perhaps, a more destructive one. Mucocutaneous Leishmaniasis is also known as ‘epsundia,’ and it can occur after the resolution of the cutaneous variant. Herein, you will see erosion/lesions of the upper airway tract, such as the nose, mouth, pharynx, and larynx. ML can destroy and disfigure the nasal septum and the aerodigestive tract, and hence, it is known as a malignant variant of Leishmaniasis.

Visceral Leishmaniasis (VL):

This entity is also termed as ‘Kala-azar’ in South East Asia. Herein, there is the invasion of the protozoa beyond the skin and mucous membranes into the viscera. It commonly affects the liver, spleen, lymph nodes, and bone marrow of the patient. VL is the most severe form of Leishmania infestation and can even result in the death of the patient if left untreated.
VL tends to affect poverty-stricken areas more. Symptoms may manifest weeks, months, or years after the inoculation.

Is Leishmaniasis contagious?

Leishmaniasis is not contagious. You cannot catch it from a person like you catch the flu. A female sandfly is required to transfer the protozoa into a person’s bloodstream.
Living in an area endemic to the disease or living around people affected by it can increase your chances of getting one if vectors are predominant in your area.
L. Infantum⁷ can be transferred from mother to child.
Shared needles also act as one of the sources of parasitic transmission.

Symptoms of Leishmaniasis:

Leishmaniasis can be exhibited differently, given the type of disease.

Cutaneous lesions:⁸ These may begin as bumps and then enlarge to form an ulcer. These ulcers are usually painless unless infected secondarily by bacteria. The cutaneous variety is generally limited and self-resolving. Severe forms of cutaneous leishmaniasis can occur as diffuse lesions in immunocompromised individuals.

Mucosal ulcers: Lesions can also occur in the mucosa of the mouth, nose, pharynx, larynx, and trachea. Tracheal and laryngeal ulcers can exhibit respiratory distress and may, as well, be life-threatening.⁹

Destruction of nasal septum
Cancrum oris: Lesions of the tongue
Inflammation of gums (gingivitis)
Fever
Body Weight
Weight loss
Low hemoglobin or red blood cell count (anemia)
Enlarged liver and spleen (hepatosplenomegaly)
Fever
Body aches
Enlarged lymph nodes (lymphadenopathy)

Diagnosis of Leishmaniasis:

The diagnosis of Leishmaniasis is a combination of clinical, biochemical, and histopathological approaches.
The symptoms resemble many other diseases, such as brucellosis, malignancy of the oral and nasal cavity, etc. Hence, we should follow a systematic approach to achieve better treatment outcomes.

History & Physical Examination:

Each time you visit your doctor for anything, your doctor will ask you to go through a series of questions that form a part of your history.
Whenever leishmaniasis is suspected, traveling history is crucial, especially a trip to tropical regions or parts of the world where it’s endemic.
Regarding physical exam, the presence of cutaneous ulcers, mucous ulcers, fever, anemia, enlarged liver, and spleen, coupled with relevant history, leads to the diagnosis of Leishmaniasis.

Blood Workup:

Once leishmaniasis is suspected, your doctor will advise some blood tests to confirm the diagnosis.

Complete Blood Count (CBC)

The complete blood count of a leishmaniasis patient will not exhibit significant changes if the disease is of the mild variety. However, with more severe forms, a decrease in the count of all three cell lines, i.e., anemia, leukopenia, and thrombocytopenia, shall be present (indicating bone marrow infiltration by the parasite).

Peripheral Blood Smear

In case your CBC comes out normal, and your doctor is still worried about your diagnosis, they may request a peripheral blood smear wherein smear slides are specifically looked up for the presence of abnormal cells and parasites. Leishmaniasis is represented in peripheral blood smears as ‘Amastigotes’ inside the neutrophils and monocytes.

Liver Function Tests (LFTs)

Visceral Leishmaniasis can affect liver function significantly. Hence, your doctor would be interested in looking up your liver enzymes if they suspect leishmaniasis.

Histopathology:

A biopsy is the definite way to confirm a diagnosis. A histopathologist examines the cutaneous lesions using a wedge biopsy from the edge of the lesion. The higher the parasitic burden in the lesion, the more specific the results.
In the case of mucocutaneous leishmaniasis (ML), the doctor should take samples from dental or oral scrapings. Giemsa staining may reveal the parasite; however, it may be difficult to isolate the protozoan from the mucosa. The tissues affected by Leishmaniasis almost always contain non-specific granulomatous inflammation.
Visceral Leishmaniasis may require some extensive workup. Pancytopenia (decrease in all three blood cell lines) requires bone marrow aspiration for confirmation. Similarly, your doctor might also collect samples from liver and splenic tissue samples under radiological guidance if laboratory findings are not conclusive.

Serology:

These days, doctors use Polymerase chain reaction tests (PCR) to detect viruses and parasites in blood. These investigations come with high sensitivity and specificity. They save you from undergoing invasive investigations.
Real-time PCR assay¹⁰ detects leishmaniasis parasite DNA in serum.

Leishmaniasis Treatment

Different types of leishmaniasis require treatment targeted for its kind. Moreover, leishmaniasis treatment responds differently depending on the variant and concentration of the parasite in the affected tissue or organ.
Here is a brief piece of information you may find useful regarding the treatment of leishmaniasis.¹¹

How to treat Cutaneous Leishmaniasis?

This variant usually resolves within 3-6 months without any intervention. Those lasting more than 6 months or are rapidly progressive, erosive, or disfiguring need medical attention after confirmation of diagnosis.

Local treatment with pentavalent antimonial: Infiltration of the lesion at its base with melgumine antimoniate or sodium stibogluconate (1-2ml) every 3 to 7 days for 2 to 4 weeks. Once healing begins, your doctor might halt your treatment.
Systemic treatment: Severe forms of cutaneous leishmaniasis can respond to an intramuscular dose of pentavalent antimonial; however, it must be done so under close medical supervision.
Oral Miltefosine for 28 days is also effective against cutaneous Leishmaniasis.
In case of secondary infection with bacteria, use wide-spectrum antimicrobials or narrow-spectrum (if the exact organism sensitivity is known).

Treatment for Mucocutaneous & Visceral Leishmaniasis:

Treatment guidelines are different for each strain. For all forms of leishmaniasis, the patient should ensure good hydration, nutritional support, and hygienic practices.

Visceral & Mucocutaneous Leishmaniasis in East Africa:

First-line treatment: IM or slow IV administration of a pentavalent antimonial coupled with paromomycin for 17 days.
Second-line treatment: It is for relapsed cases, severe disease forms, pregnant patients, and those aged over 45 years. It includes liposomal amphotericin B IV once daily for 6-10 days.
HIV patients: Liposomal amphotericin B IV once daily for 6-10 days with miltefosine PO for 28 days.

Visceral & Mucocutaneous Leishmaniasis in South Asia:

First-line treatment: Liposomal amphotericin B IV once daily for 3 to 5 days.
Second-line treatment: If the first-line treatment fails, then liposomal amphotericin B IV once daily for 5 to 8 days.

Complications of Leishmaniasis:

The complications of leishmaniasis are as varied as its clinical forms, ranging from cosmetic concerns to life-threatening conditions.

Scar Formation: In its milder forms, the disease may leave behind physical scars that alter a person’s appearance and carry a significant emotional toll, especially for individuals in communities where visible disfigurement can lead to social stigma.
Secondary Infections and Sepsis: In more severe cases, complications escalate dramatically. For instance, untreated skin lesions can become a gateway for bacterial infections, sometimes evolving into systemic problems like sepsis—a critical condition requiring urgent medical intervention.
Septal Perforation: Patients with the mucocutaneous form may suffer nasal septum perforation, leading to difficulties in breathing and speech, alongside aesthetic challenges.
Post Kala-Azar Dermal Leishmaniasis (PKDL) and Organ Damage (Hemophagocytic Lymphohistiocytosis, HLH): Visceral leishmaniasis, often termed “kala-azar,” poses even graver risks. The parasite can infiltrate major organs, resulting in conditions like pneumonia, gastrointestinal infections, or even hemophagocytic lymphohistiocytosis (HLH)—a rare but fatal immune response that causes the body to attack its own cells. Another unique consequence is post-kala-azar dermal leishmaniasis (PKDL), where a distinct rash appears during or after recovery, sometimes serving as a reservoir for further disease transmission.

Without timely treatment, patients may also face the risk of severe bleeding due to compromised organs, igniting the need for early detection and comprehensive care. These complications underline the systemic challenges associated with leishmaniasis, affecting not just the individual but the broader healthcare landscape perspective, focusing on the emotional, physical, and systemic implications of the complications.

Is Leishmaniasis curable?

Yes, leishmaniasis is curable. With timely diagnosis and treatment, the success rate for cutaneous leishmaniasis is about 90%, while for visceral leishmaniasis, it’s around 75%. However, delayed treatment can lower the chances of success. The effectiveness of treatment also depends on the individual’s immune system—people with a strong immune response tend to have better outcomes, whereas immunocompromised individuals may face a poorer prognosis. Additionally, there is a risk of relapse or re-infection after recovery.

Leishmaniasis Prevention

Currently, there is no vaccine to shield against leishmaniasis, making preventive measures essential, particularly for those living in or traveling to endemic regions. The key to prevention is minimizing exposure to sandflies, the tiny yet persistent vectors of the disease.

To protect yourself, prioritize wearing protective clothing, such as long sleeves and full-length pants, especially during peak sandfly activity at dusk and dawn.
Additionally, insect repellents that are EPA-approved should become a staple of your daily routine when venturing into high-risk areas.
Creating a barrier between you and sandflies is also critical. Opt for fine-mesh insect nets treated with insecticide to cover beds or sleeping spaces, ensuring they are tightly secured to prevent entry through even the smallest gaps.
For extra precaution, spray living spaces or tents with effective insecticides to deter sandflies from settling indoors.

By adopting these measures, you can significantly reduce the risk of leishmaniasis, making awareness and consistent action your strongest tools for staying protected.

Conclusion

Leishmaniasis is a multifaceted disease transmitted by sandflies, manifesting in diverse ways depending on the individual’s age, health status, and type of infection. While anyone can be affected, immunocompromised individuals, such as young children, the elderly, or those with underlying health conditions, face the most severe consequences.
Although effective treatments are available, the disease often leaves lasting physical and emotional scars, reminding us that prevention is always better than cure. Protecting vulnerable populations by raising awareness and promoting preventive measures is not just a medical responsibility—it’s a community effort. By prioritizing prevention, we can reduce the burden of this debilitating disease and improve the quality of life in affected regions.

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Leishmaniasis: What You Need to Know

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