Visceral Leishmaniasis, commonly known as Kala-Azar, is a life-threatening parasitic disease caused by the protozoa Leishmania donovani. It is transmitted by the bite of infected female sandflies and is prevalent in tropical and subtropical regions, especially in parts of India, Bangladesh, Nepal, Sudan, and Brazil.
This article provides an extensive overview of visceral leishmaniasis, covering its clinical features, pathogenesis, diagnostic approaches, treatment options, and preventive measures, while optimizing for high-impact keywords like Kala-Azar symptoms, Leishmania diagnosis, and treatment for visceral leishmaniasis.
What is Visceral Leishmaniasis?
Kala-Azar, derived from Hindi meaning "black fever", is the most severe form of leishmaniasis. It affects the reticuloendothelial system — particularly the spleen, liver, and bone marrow.
Without treatment, visceral leishmaniasis has a high mortality rate, primarily due to immune suppression, secondary infections, and pancytopenia.
Causes of Visceral Leishmaniasis
- Causative agent: Leishmania donovani, L. infantum, or L. chagasi (species vary by geography)
- Transmission vector: Female Phlebotomine sandflies
- Reservoirs: In endemic areas, humans (India) and dogs (Mediterranean, Latin America)
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Mnemonic for Symptoms:
"She Had No Fever But She Complained of Weakness"
This easy-to-remember sentence captures the major clinical features of visceral leishmaniasis:
| Mnemonic Element | Clinical Feature |
|---|---|
| She | Splenomegaly |
| Had | Hepatomegaly |
| No | Night sweats |
| Fever | Fever |
| But | Blackening of skin |
| She | Scaly skin |
| Complained | Cough |
| of Weakness | Weakness and weight loss |
Symptoms of Kala-Azar
Visceral leishmaniasis is typically progressive and systemic, presenting over weeks or months. Here's a breakdown of the common clinical manifestations:
1. Splenomegaly
The most prominent feature — spleen is often massively enlarged and tender.
2. Hepatomegaly
Liver enlargement follows splenic involvement and may contribute to abdominal fullness.
3. Fever
Intermittent or continuous, usually lasting several weeks. In some cases, patients may be apyretic despite infection.
4. Night Sweats
Associated with fever and systemic immune response.
5. Blackening of Skin
Gives the disease its Hindi name "Kala-Azar." The pigmentation typically affects the face, hands, feet, and abdomen.
6. Scaly Skin
Due to chronic inflammation, dehydration, or malnutrition. Can resemble eczema or dermatitis.
7. Cough
Indicative of lung involvement or secondary infections, especially in advanced disease.
8. Weight Loss and Weakness
Due to prolonged illness, poor appetite, and metabolic imbalance.
Epidemiology
| Parameter | Details |
|---|---|
| Global burden | > 50,000–90,000 new cases annually |
| High-risk areas | India (Bihar, Jharkhand, West Bengal), Sudan, Brazil |
| At-risk population | Children, immunocompromised individuals, HIV+ |
| Seasonality | Higher incidence in warm, humid seasons |
Pathophysiology
After inoculation by the sandfly, promastigotes enter macrophages and convert into amastigotes, multiplying and spreading through the reticuloendothelial system.
Key effects include:
- Pancytopenia (due to bone marrow suppression)
- Hypergammaglobulinemia
- Hepatosplenomegaly
- Protein-energy malnutrition
- Immunosuppression
Diagnostic Approach
1. Clinical Suspicion
- Travel or residence in endemic area
- Chronic fever, hepatosplenomegaly, pancytopenia
2. Laboratory Tests
| Test | Findings |
|---|---|
| Complete blood count (CBC) | Anemia, leukopenia, thrombocytopenia |
| Liver function tests | Elevated bilirubin, transaminases |
| Serum protein | Hypergammaglobulinemia |
3. Parasitological Diagnosis
- Splenic aspiration (gold standard, highest yield but risky)
- Bone marrow aspiration
- Lymph node biopsy (in some cases)
- Demonstration of amastigotes (Leishman-Donovan bodies) in macrophages
4. Serological Tests
- rK39 dipstick test (rapid and widely used in field settings)
- Direct agglutination test (DAT)
- ELISA or IFAT (more sensitive but costlier)
5. Molecular Methods
- PCR (polymerase chain reaction) for DNA of Leishmania in clinical specimens
- Highly sensitive and specific but not widely available in low-resource settings
Complications
If untreated, visceral leishmaniasis can result in:
| Complication | Description |
|---|---|
| Pancytopenia | Increased risk of bleeding, infections |
| Secondary bacterial infections | Pneumonia, sepsis due to immune compromise |
| Post-kala-azar dermal leishmaniasis (PKDL) | Skin lesions occurring after treatment |
| Liver failure | From persistent hepatic inflammation |
| Death | Due to overwhelming infection or hemorrhage |
Treatment of Visceral Leishmaniasis
Effective therapy is crucial for survival. Drug of choice varies based on region, resistance, and availability.
1. First-Line Drugs
| Drug | Dosage / Duration | Comments |
|---|---|---|
| Liposomal Amphotericin B | 10 mg/kg (single dose) | Preferred by WHO; minimal toxicity |
| Miltefosine | Oral, 28 days | Teratogenic, avoid in pregnancy |
| Paromomycin | 15 mg/kg IM daily for 21 days | Aminoglycoside derivative |
| Pentavalent antimonials | Sodium stibogluconate (20 mg/kg/day) for 28–30 days | High resistance in India |
2. Combination Therapy
- Miltefosine + Paromomycin
- Liposomal Amphotericin B + Miltefosine
Used to reduce emergence of resistance, shorten treatment duration, and improve compliance.
Post-Kala-Azar Dermal Leishmaniasis (PKDL)
- Occurs in 5–10% of treated patients, especially in India
- Presents with macular, papular, or nodular skin lesions
- Reservoir for continued disease transmission
- Requires prolonged therapy with Miltefosine or Amphotericin B
Prevention and Control
1. Vector Control
- Indoor residual spraying with insecticides
- Insecticide-treated bed nets
- Sandfly habitat reduction (eliminating breeding sites)
2. Personal Protection
- Wearing long sleeves, insect repellents (DEET)
- Avoiding outdoor exposure during dusk and dawn (peak sandfly activity)
3. Public Health Measures
- Early case detection and treatment
- Community education campaigns
- Surveillance systems for monitoring outbreaks
- Dog culling (in zoonotic regions like Latin America)
WHO Elimination Strategy
India, Bangladesh, and Nepal launched a regional initiative in 2005 with WHO support to eliminate Kala-Azar as a public health problem. The goal is to reduce incidence to <1 case per 10,000 people annually at district level.
Key components:
- Use of rK39 test
- Deployment of single-dose liposomal amphotericin B
- Strengthened surveillance and case management
Kala-Azar in HIV Patients
Co-infection with HIV leads to:
- Atypical presentations
- Lower response to treatment
- Frequent relapses
- Higher mortality
Requires lifelong monitoring
ART should be initiated alongside anti-leishmanial therapyKey Differences: Cutaneous vs. Visceral Leishmaniasis
| Feature | Cutaneous | Visceral (Kala-Azar) |
|---|---|---|
| Organ involved | Skin | Spleen, liver, bone marrow |
| Symptoms | Ulcerated skin lesions | Fever, hepatosplenomegaly |
| Mortality | Rare | High if untreated |
| Causative species | L. tropica, L. major | L. donovani |
| Transmission | Sandfly | Sandfly |
Frequently Asked Questions (FAQs)
Q1. Why is it called Kala-Azar?
A: "Kala-Azar" means "black fever" in Hindi, referring to skin darkening seen in some patients.
Q2. Is Kala-Azar contagious between humans?
A: No. It is not transmitted from person to person. It spreads via sandfly bites.
Q3. Can Kala-Azar be fatal?
A: Yes. If untreated, it is almost always fatal due to secondary infections or organ failure.
Q4. How effective is the rK39 test?
A: Highly sensitive in endemic areas; however, false positives may occur in post-treatment PKDL or other diseases.
Q5. What is the treatment of choice in India?
A: Single-dose Liposomal Amphotericin B is preferred due to low toxicity and high cure rates.
Summary Table: Visceral Leishmaniasis at a Glance
| Feature | Description |
|---|---|
| Alternate Name | Kala-Azar |
| Causative Agent | Leishmania donovani |
| Vector | Phlebotomine sandfly |
| Common Symptoms | Fever, hepatosplenomegaly, weight loss |
| Diagnosis | rK39 test, splenic aspirate |
| Treatment of Choice | Liposomal Amphotericin B |
| Complication | Post-Kala-Azar Dermal Leishmaniasis |
| Prevention | Vector control, personal protection |
| High-Burden Regions | Bihar (India), Sudan, Bangladesh |
