Leishmaniasis is a critical parasitic disease caused by the Leishmania parasites, which are transmitted through the bite of infected sandflies. This disease affects millions worldwide and is predominantly seen in tropical and subtropical regions. It manifests as cutaneous, mucocutaneous, and visceral forms in the body. 

This condition is often linked to poverty, malnutrition, and poor living conditions. Understanding its pathogenesis, clinical features, diagnostic methods, and treatment protocols is essential for competitive exams. 

Read this article further for a comprehensive guide to help you tackle leishmaniasis-related questions with confidence. 

What is Leishmaniasis? 

Leishmaniasis is a disease caused by an obligate intracellular protozoan from the Leishmania donovani complex. The parasites are transmitted by the bite of an infected female phlebotomine sandfly, which inserts promastigotes into the skin. These promastigotes are phagocytosed by macrophages and form amastigotes, known as ID bodies, which multiply intracellularly. 

Listed below is the clinical classification of leishmaniasis: 

• Cutaneous Leishmaniasis (CL): It is mainly caused by L. tropica, L. major, and L. mexicana and typically affects the skin, leading to ulcerative lesions.
• Mucocutaneous Leishmaniasis (MCL): It is caused by the L. braziliensis complex and involves the mucosal surfaces of the oropharynx and nasal septum.
• Visceral Leishmaniasis (VL/Kala-azar): It is caused by L. donovani, L. infantum, and L. chagasi and usually affects the reticuloendothelial system, including the liver, spleen, and bone marrow.

What are the Causes and Risk Factors of Leishmaniasis?

Leishmaniasis is caused by protozoan parasites of the Leishmania genus, which are primarily transmitted through the bite of infected sandflies. Understanding its causes and risk factors is essential for both diagnosis and prevention: 

Etiological Agent: Protozoan parasites of the leishmania genus (order: kinetoplastida, family: trypanosomatidae)

Modes of Transmission: Leishmaniasis can be transmitted via the bite of an infected female phlebotomine sandfly or as infective promastigotes, injected and converted into amastigotes inside human macrophages. 

Risk Factors: 

• Genographic Endemicity: Common in India, Nepal, Sudan, Brazil, and Ethiopia. 
• Malnutrition: Common in cases of protein-energy malnutrition, which impairs the proper functioning of cell-mediated immunity.
• Immunosuppression: HIV/AIDS co-infection dramatically increases susceptibility and alters disease presentation. 
• Poor Housing and Sanitation: Unhygienic environments favour the breeding of sandflies and increase human-vector contact.
• Occupational Exposure: Forest workers, agricultural labourers, and individuals operating in endemic areas are at higher risk.
• Climate and Environmental Changes: These changes may expand the habitat range of sandflies, increasing transmission zones.

What are the Symptoms of Leishmaniasis?     

Symptoms of leishmaniasis vary by type, ranging from skin ulcers to life-threatening systemic manifestations affecting internal organs and immune function. Listed below are the symptoms of the variants of leishmaniasis: 

Skin Sores

Cutaneous leishmaniasis (CL), the most common form, is characterised by skin sores that typically change in size and appearance over time.

They may start as papules or nodules, later progressing into painless ulcers in most cases. These manifestations are typically seen on the arms or hands.

Fever

Visceral leishmaniasis is a very severe form of leishmaniasis that affects the internal organs and can be severely life-threatening. A common manifestation seen in VL is fever accompanied by weight loss. 

Enlargement of Spleen and Liver

Splenomegaly and hepatomegaly are common manifestations seen with visceral leishmaniasis, which occur due to parasite infiltration, immune cell hyperplasia, and chronic inflammation within the reticuloendothelial system. 

Abnormal Blood Test

Anaemia, leukopenia, and thrombocytopenia are common findings seen in visceral leishmaniasis caused by bone marrow suppression and secondary bacterial infections.

How is Leishmaniasis Diagnosed? 

Leishmaniasis presents distinct clinical forms, each with its own characteristics, symptoms, and complications. Accurate diagnosis relies on clinical evaluation supported by parasitological, serological, and molecular methods:

Clinical Evaluation 

A doctor is required to perform a physical examination to check for the presence of cutaneous, mucocutaneous, and visceral lesions in the form of ulcers or nodules that are usually seen on the arm and the forearm.

Parasitological Methods

Microscopy methods detect amastigotes (LD bodies) in bone marrow, splenic aspirates, or lymph node biopsies. Culture samples are also used to show the growth of promastigotes over a sample culture in Novy-MacNeal-Nicole (NNN) medium. 

Molecular Methods 

Methods such as polymerase chain reaction are highly specific and sensitive. They detect leishmania DNA from clinical samples, aiding in species identification.

Serological Testing 

Rapid diagnostic tests, direct agglutination tests, and ELISA are commonly used in endemic areas for detecting anti-leishmania antibodies. 

Histopathology

A biopsy of the affected tissue shows the presence of amastigotes or LD antibodies within the macrophages, which is a confirmatory sign of the disease.

What are the Treatment Options for Leishmaniasis?

The treatment of leishmaniasis depends on the variant of leishmaniasis. Listed below are the methods of treatment of leishmaniasis based on its variations: 

Type	Drug/Treatment	Route	Dosage (Typical)	Advantages	Comments/Notes
Visceral (VL)	Liposomal Amphotericin B	IV	10 mg/kg (single or divided doses)	Highly effective, less toxic	WHO preferred; costly
	Amphotericin B deoxycholate	IV	0.75–1 mg/kg/day for 15–20 days	Effective, cheaper	More toxic (nephrotoxicity)
	Miltefosine	Oral	2.5 mg/kg/day (for 28 days)	Oral, well-tolerated	Teratogenic; not for pregnant women
Cutaneous (CL)	Local Cryotherapy or Thermotherapy	Local	1–2 sessions	Minimally invasive	Effective in early localised lesions
	Intralesional Antimonials	Injection	2–5 doses weekly	Targeted treatment	Useful for small or few lesions
	Paromomycin Ointment	Topical	2× daily for 20–30 days	Non-invasive	Mild to moderate CL
	Miltefosine	Oral	2.5 mg/kg/day for 28 days	Oral therapy	Works for L. panamensis, L. braziliensis
	SSG or Meglumine antimoniate	IM/IV	20 mg/kg/day for 20 days	Widely used	Painful injections, some toxicity

FAQs About Leishmaniasis

1. What are the main causes of leishmaniasis? 

Leishmaniasis is caused by Leishmania parasites, transmitted through the bite of infected female sandflies. The parasites multiply inside human macrophages, leading to different forms of the disease.

2. How is visceral leishmaniasis (kala-azar) diagnosed? 

Diagnosis involves clinical symptoms like fever and splenomegaly, and is confirmed by the identification of LD bodies in aspirates or PCR-based molecular testing for species detection.

3. Which treatment is considered safest during pregnancy?

Liposomal amphotericin B is the safest treatment for leishmaniasis in pregnancy due to its low toxicity and no teratogenic effects. 

4. How can leishmaniasis be prevented?

Leishmaniasis can be prevented by utilising nets, repellents, protective clothing, and improving housing and sanitation conditions.

Conclusion

Leishmaniasis is a major parasitic disease with diverse clinical forms, ranging from skin ulcers to life-threatening systemic illness. Early diagnosis and tailored treatment are essential for managing its manifestations. Whether it is understanding the differences between CL, MCL, and VL or mastering the diagnostic protocols, a solid grasp of the topic is vital for NEET PG aspirants.

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