Leishmaniasis, Visceral (Kala Azar)

Key Features

Essentials of Diagnosis

• Sand fly bite in an endemic area

• Irregular fever, progressive hepatosplenomegaly, pancytopenia, wasting

• Amastigotes in macrophages in aspirates, touch preparations, or biopsies

• Positive culture, serologic tests, polymerase chain reaction (PCR), or skin test

General Considerations

• The disease is caused mainly by

  • L donovani in the Indian subcontinent and East Africa

  • L infantum in the Mediterranean, Middle East, China, parts of Asia, and Horn of Africa

  • L chagasi in South and Central America

• Other species may occasionally cause visceral disease

• In each locale, the disease has particular clinical and epidemiologic features

• Infection is transmitted by bites of sand flies

• Clinical syndromes generally dictated by infecting species, but some species cause more than one syndrome

• The incubation period is usually 4–6 months (range: 10 days to 24 months)

Demographics

• Over 90% of cases occur in seven countries

  • Brazil

  • Ethiopia

  • India

  • Kenya

  • Somalia

  • South Sudan

  • Sudan

• The estimated annual incidence of disease has been decreasing; current estimate is 50,000–90,000

• Progress against visceral disease has been greatest on the Indian subcontinent

Clinical Findings

Symptoms and Signs

• Most infections are subclinical

• A small number progress to full-blown disease

• A local nonulcerating nodule at the site of the sand fly bite may precede systemic manifestations but usually is inapparent

• Onset may be acute, within 2 weeks of infection, or insidious

• Fever, chills, sweats, weakness, anorexia, weight loss, cough, and diarrhea

• Spleen progressively becomes greatly enlarged, firm, and nontender

• Liver is somewhat enlarged

• Generalized lymphadenopathy may occur

• Hyperpigmentation of skin can be seen, leading to the name kala azar ("black fever")

• Skin lesions, petechiae, gingival bleeding, jaundice, edema, and ascites

• As the disease progresses, severe wasting and malnutrition are seen

• Viscerotropic leishmaniasis has been reported in small numbers of American military personnel in the Middle East, with mild systemic febrile illnesses after L tropica infections

• Can present late in course of HIV infection

  • Fever, hepatosplenomegaly, pancytopenia

  • Gastrointestinal tract, respiratory tract, and skin may also be involved

Differential Diagnosis

• Leukemia or lymphoma

• Cirrhosis

• Tuberculosis

• Histoplasmosis

• Infectious mononucleosis

• Brucellosis

• Malaria

• Typhoid fever

• Schistosomiasis

• African trypanosomiasis

• Tropical splenomegaly syndrome

Diagnosis

Laboratory Tests

• Cultures with media available from the CDC will grow promastigotes within a few days to weeks

• Molecular assays can also be diagnostic

• Serologic tests

  • May facilitate diagnosis

  • None are sufficiently sensitive or specific to be used alone

• Numerous antibody-based rapid diagnostic tests are available

  • Specificity is good

  • Sensitivity outside of India is limited

Diagnostic Procedures

• Fine-needle aspiration of spleen for culture and tissue evaluation

  • Generally safe

  • Yields a diagnosis in over ...