Visceral Leishmaniasis

Dr. Eatimad Mahgoub Osheik

Learning Objectives

By the end of this lecture, you should be able to:

Describe the epidemiology and life cycle of Leishmania
Classify different types of leishmaniasis
Understand pathogenesis of visceral leishmaniasis
Recognize clinical features and complications
Discuss diagnosis, treatment, and prevention

Introduction

Leishmaniasis is a protozoal disease with the following characteristics:

Caused by Leishmania species
Transmitted by the bite of female sandfly
An important neglected tropical disease
Affects skin, mucosa, or internal organs

Global Epidemiology

Geographic Distribution:

Endemic in tropical and subtropical regions
Found in Asia, Africa, South America, and Mediterranean regions
90% of Visceral Leishmaniasis cases occur in:
- India
- Bangladesh
- Sudan
- Brazil
- Ethiopia

Disease Burden

Prevalence: Around 12 million people infected globally
Incidence: ~0.7–1.2 million Cutaneous Leishmaniasis cases and 0.2–0.4 million Visceral Leishmaniasis cases annually
Mortality: VL is fatal if untreated (>95% of cases)

Risk Factors

Socioeconomic:

Poverty
Malnutrition
Poor housing
Lack of resources

Environmental:

Rainforests
Peri-urban areas
Proximity to animal reservoirs (rodents)

Immune Status:

Compromised immunity
HIV co-infection (especially significant)

Human Behaviour:

Population movement
Lack of awareness

Causative Organism

Leishmania is an obligate intracellular protozoa that belongs to the Kinetoplastida class.

Old World Species (Africa, Asia, Europe)

L. tropica, L. major, L. aethiopica → Cutaneous leishmaniasis
L. donovani, L. infantum → Visceral leishmaniasis

New World Species (Americas)

L. mexicana, L. amazonensis → Cutaneous / diffuse cutaneous leishmaniasis
L. braziliensis → Mucocutaneous leishmaniasis
L. chagasi (= L. infantum) → Visceral leishmaniasis

Life Cycle of Leishmania Parasite

Overview: The Leishmania parasite’s life cycle involves two hosts: a sandfly vector and a mammalian host. The parasite alternates between flagellated promastigotes (in the fly) and non-flagellated amastigotes (in the mammal).

Vector

Female Sandfly characteristics:

Phlebotomus (Old World)
Lutzomyia (New World)
Small, silent, night-biting insect
Breeds in:
- Cracks in walls
- Cattle sheds
- Organic waste

Leishmania Parasite Reservoir

Natural reservoirs include:

Dogs
Rodents
Humans
Wild animals (e.g., Foxes, Jackals)

Life Cycle Steps

Sandfly bites infected human → ingests amastigotes
In sandfly gut → transform into promastigotes
Promastigotes multiply and migrate to mouth
Sandfly bites human → injects promastigotes
Promastigotes enter macrophages → become amastigotes
Multiply intracellularly → cell rupture → systemic spread

Target Organs

The parasite primarily targets:

Spleen
Liver
Bone marrow
Lymph nodes

Clinical Classification of Leishmaniasis

Based on Clinical Manifestations

Visceral Leishmaniasis (VL)
Cutaneous Leishmaniasis (CL)
Mucocutaneous Leishmaniasis (MCL)
Post-Kala-azar Dermal Leishmaniasis (PKDL)

Cutaneous Leishmaniasis

Causative Organisms:

L. tropica
L. major

Clinical Features:

Localized to skin
Lesion progression: Papule → nodule → ulcer
Usually painless
Heals with scarring
Known as “Oriental sore”

Diffuse Cutaneous Leishmaniasis

Characteristics:

Rare form
Associated with poor cell-mediated immunity
Multiple nodular lesions
Resembles lepromatous leprosy
Difficult to treat

Mucocutaneous Leishmaniasis

Causative Organism:

Leishmania braziliensis

Affected Structures:

Nasal septum
Oral cavity
Pharynx

Consequences:

Severe tissue destruction
Facial disfigurement
Common in South America

Post-Kala-azar Dermal Leishmaniasis (PKDL)

Timing:

Occurs after treatment of VL
Develops months to years post-treatment

Clinical Manifestations:

Hypopigmented macules
Papules
Nodules
No systemic symptoms

Epidemiological Significance:

Serves as reservoir of infection
Important in disease transmission

Visceral Leishmaniasis (VL) - “Kala-azar” (The Black Fever)

Overview:

Severe, potentially fatal disease
Caused by Leishmania donovani and Leishmania infantum (chagasi)
Targets internal organs (spleen, liver, and bone marrow)
High mortality if untreated

Pathogenesis of Visceral Leishmaniasis (Kala-azar)

Incubation Period:

2–6 months, but can extend up to 2 years

Mechanism of Spread:

Amastigotes multiply within macrophages
Spread via blood and lymphatics
Parasites primarily invade the reticuloendothelial system (spleen, liver, bone marrow, and lymph nodes)

Systemic Manifestations:

Splenomegaly
Hepatomegaly
Lymphadenopathy
Anemia
Leukopenia
Thrombocytopenia

Immune Consequences:

Progressive immune suppression occurs due to macrophage dysfunction

Effects of Visceral Leishmaniasis on the Immune System

Cellular Immunity Suppression:

The parasite infects macrophages and suppresses protective cell-mediated (Th1) immunity
Leads to reduced IFN-γ and IL-12 production

Immunosuppressive Response:

Increased immunosuppressive cytokines (IL-10) which allow parasite survival
Immune response shifts toward ineffective humoral (Th2) response - causing polyclonal B-cell activation and hypergammaglobulinemia

Clinical Presentation of Visceral Leishmaniasis

Fever:

Irregular, prolonged bouts

Constitutional Symptoms:

Progressive and severe weight loss
General weakness
Malaise
Anorexia
Fatigue

Physical Examination Findings:

Hepatosplenomegaly: Enlarged, non-tender spleen and liver causing abdominal swelling

Laboratory Abnormalities:

Pancytopenia: Anemia, leucopenia, thrombocytopenia

Dermatologic Manifestations:

Skin darkening or spots

Hemorrhagic Manifestations:

Bleeding: Petechiae or bruising

Diagnostic Studies

1. Parasitological Diagnosis (Gold Standard)

Detection Method: Detects Leishmania amastigotes (Leishman Donovan LD bodies)

Splenic Aspirate Microscopy:

Sensitivity: ~95%
Risk: Bleeding (needs expertise)

Bone Marrow Aspirate:

Sensitivity: 60–85%
Advantages: Safer, commonly used

Lymph Node Aspirate:

Lower sensitivity

Culture:

Confirms species identity
Slow process

2. Serological Tests (Antibody Detection)

Useful for screening and diagnosis in endemic areas

rK39 Immunochromatographic Test (ICT):

Rapid, field-friendly
High sensitivity & specificity

Direct Agglutination Test (DAT):

Highly sensitive
Quantitative

ELISA:

Sensitive
Lab-based

IFA (Indirect Fluorescent Antibody Test):

Specialized laboratory test

Limitations of Serological Tests:

Cannot distinguish past vs. active infection
Lower sensitivity in HIV co-infection
Antibodies persist after cure

3. Antigen Detection

KAtex (Urine Latex Agglutination Test):

Detects leishmanial antigen in urine
Useful for treatment monitoring
Lower sensitivity than rK39

4. Molecular Tests

PCR (Polymerase Chain Reaction):

Performed on blood, bone marrow, splenic aspirate
Very high sensitivity & specificity
Useful in HIV-VL, relapse, and low parasite load scenarios
Limitations: Expensive, limited availability

5. Skin Test

Montenegro (Leishmanin) Skin Test:

Negative in active VL
Becomes positive after cure
Not useful for diagnosis of active disease

6. Supportive Laboratory Findings (Non-specific)

Pancytopenia (anemia, leukopenia, thrombocytopenia)
Hypergammaglobulinemia
Elevated ESR (Erythrocyte Sedimentation Rate)
Hypoalbuminemia

Management

Supportive Care

Adequate nutrition
Correction of anemia
Treatment of secondary infections
Antipyretics for fever
Management of bleeding and thrombocytopenia

Treatment

WHO-Approved Medications for Visceral Leishmaniasis

Several medicines have been approved by the World Health Organization (WHO) to treat VL cases:

Pentavalent antimony
Amphotericin B deoxycholate
Lipid formulation of amphotericin B (e.g., liposomal amphotericin B)
Paromomycin
Miltefosine

Note: Pentavalent antimony has been used for several decades and remains effective against VL.

Drugs Registered in Saudi Arabia:

Pentavalent antimonials (sodium stibogluconate & meglumine antimoniate)
Ambisome (liposomal amphotericin B)

Pentavalent Antimonials

Formulations:

Sodium stibogluconate solution: 100 mg/ml
Meglumine antimoniate solution: 81 mg/ml

Dosage:

20 mg/kg/day × 30 days
Route: Intramuscular or intravenous infusion

Side Effects:

Cardiotoxicity
Fatal arrhythmia

Contraindications:

Elderly patients
Significant heart, liver, or kidney disease
Pregnancy

Ambisome (Liposomal Amphotericin B)

Advantages:

Similar efficacy to amphotericin B
Significantly less toxic than standard formulation

Side Effects:

Transient nephrotoxicity
Thrombocytopenia
Hypokalemia

Dosage:

3 mg/kg/day
Route: Intravenous

Clinical Use:

Recommended for resistant cases
Use when pentavalent antimony’s are contraindicated

Complications of Visceral Leishmaniasis (Kala-azar)

Overwhelming bacterial infections (most common cause of death)
Severe bleeding
Extreme weight loss
Anemia
Hepatosplenomegaly leading to organ failure
Disfiguring skin issues (PKDL)
Disease relapse

Prevention & Control

Individual Level

Early diagnosis and treatment
Use of bed nets
Personal protection

Vector Control

Indoor residual spraying (DDT / pyrethroids)
Environmental sanitation

National Programs

Kala-azar Elimination Programme
Target: <1 case per 10,000 population

Vaccination Against Leishmaniasis

Current Status:

No licensed vaccine available for human leishmaniasis
Several candidates are in various stages of development
Some showing promising results in animal models and early human trials
DNA vaccines (e.g., LEISHDNAVAX) showing potential

Case Scenario

Clinical Presentation

A 32-year-old male farmer from Sudan presents to the outpatient department with the following complaints:

Chief Complaints:

Prolonged fever for the past 8 weeks
Fever is intermittent, associated with chills and night sweats
Progressive weakness
Significant weight loss
Loss of appetite
Increasing abdominal fullness

Physical Examination (O/E)

General Appearance:

Looks ill, pale, and emaciated
Temperature: 38.5°C
Pulse: 98 beats/min
Blood Pressure: 110/70 mmHg

Abdominal Examination:

Spleen: Palpable 8 cm below the left costal margin
Moderate hepatomegaly

Systemic Examination:

Generalized lymphadenopathy
Hyperpigmentation of the skin

Laboratory Investigations

Hematologic Parameters:

Hemoglobin: 8.5 g/dL
Total leukocyte count: 2,500/mm³
Platelet count: 90,000/mm³

Serological & Parasitological Testing:

rK39 rapid test: Positive
Bone marrow aspiration: Presence of LD bodies

Biochemical Parameters:

Liver function tests: Mildly elevated

Diagnosis: Visceral Leishmaniasis (Kala-azar) caused by Leishmania donovani

Diagnostic Reasoning

This patient presents the classic triad of VL:

Clinical Feature	Patient Finding	Pathophysiological Basis
Demographics	32-year-old male farmer from Sudan	Sudan is among the 5 countries accounting for 90% of global VL cases (endemic region)
Prolonged fever	8 weeks, intermittent with chills	Immune dysregulation with macrophage dysfunction; persistent parasitemia
Hepatosplenomegaly	Massive splenomegaly (8 cm), moderate hepatomegaly	Parasite invasion of reticuloendothelial system (spleen, liver, bone marrow)
Pancytopenia	Hb 8.5 g/dL, WBC 2,500/μL, Plt 90,000/μL	Bone marrow suppression + hypersplenism + peripheral destruction
Constitutional symptoms	Severe weight loss, anorexia, weakness	Chronic inflammation, cytokine storm (IL-10 elevation), malnutrition
Skin changes	Hyperpigmentation (“Black fever”)	Accumulation of melanin; characteristic of kala-azar
Lymphadenopathy	Generalized	Reticuloendothelial proliferation
Confirmatory tests	rK39 Positive (+), LD bodies in bone marrow	rK39 ICT is highly sensitive/specific for VL; visualization of amastigotes (LD bodies) in bone marrow aspirate is the gold standard (60–85% sensitive)

Differential Diagnoses (Ruled Out)

Malaria: No mention of cyclic fever patterns or peripheral smear findings; rK39 is specific for leishmaniasis
Typhoid: Prolonged fever but would present with relative bradycardia, rose spots, and negative rK39
Tuberculosis (Disseminated): Would show granulomas, not LD bodies, in bone marrow; chest imaging typically abnormal
Lymphoma/Hematologic malignancy: Would present with lymphadenopathy but bone marrow would show malignant cells, not intracellular LD bodies; rK39 would be negative
Schistosomiasis: Can cause hepatosplenomegaly and abdominal fullness, but typically causes eosinophilia (not pancytopenia) and negative serology for Leishmania

Management Plan

1. Supportive Care (Immediate)

Transfusion: Packed red blood cells if Hb <8 g/dL with symptoms (weakness, pallor)
Nutritional rehabilitation: High-calorie diet; address severe malnutrition
Infection surveillance: Broad-spectrum antibiotics prophylactically given high risk of overwhelming bacterial infections (most common cause of death in VL)
Platelet monitoring: Risk of hemorrhage with Plt 90,000/μL; avoid IM injections until platelet recovery

2. Specific Anti-Leishmanial Therapy

First-line options based on Saudi Arabian availability and WHO guidelines:

Option A (Preferred for this case): Liposomal Amphotericin B (Ambisome)

Dose: 3 mg/kg/day IV infusion
Advantages: Less nephrotoxic than conventional amphotericin B; safer than antimonials for prolonged therapy
Monitoring: Renal function, potassium levels (hypokalemia risk), thrombocytopenia

Option B: Pentavalent Antimonials (Sodium stibogluconate or Meglumine antimoniate)

Dose: 20 mg/kg/day (IM or IV) for 30 days
Caution: Requires cardiac monitoring (QT interval) due to risk of fatal arrhythmias and cardiotoxicity
Contraindications to consider: None apparent in this young patient without mentioned cardiac/renal/hepatic disease

Alternative: Miltefosine or combination therapy if first-line fails.

3. Monitoring and Follow-up

Clinical: Defervescence within 2–4 weeks, reduction in spleen size, weight gain
Laboratory: Weekly CBC until pancytopenia resolves; repeat bone marrow aspirate if poor response
Serological: rK39 may remain positive for months; not useful for cure monitoring
Post-treatment surveillance: Monitor for Post-Kala-azar Dermal Leishmaniasis (PKDL) (hypopigmented macules/nodules appearing months to years later), which serves as a reservoir

Complications to Anticipate (Based on Pathogenesis)

Severe bacterial infections: Pneumonia, septicemia (due to immune suppression and leukopenia)
Hemorrhage: Epistaxis, GI bleeding (thrombocytopenia)
Organ failure: Splenic rupture (rare but possible with massive splenomegaly)
Relapse: Immunocompromised states (check HIV status)

Prognosis

Good if treated promptly. Without treatment, VL is universally fatal (>95% mortality). With appropriate therapy, mortality drops to <5%. Recovery of hematologic parameters typically occurs within 3–6 months.

Prevention Advice for Patient and Community

Vector control: Sleep under insecticide-treated bed nets; indoor residual spraying with pyrethroids
Early detection: Community awareness for similar symptoms (fever + abdominal swelling)
Animal reservoirs: Control of stray dogs (major reservoir for L. infantum, though L. donovani is anthroponotic in Sudan)

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