Main » Infectious diseases » Arthropod-borne Infection » Visceral Leishmaniasis (Kala-azar, Dum-Dum Fever, Black Sickness)
Distribution Visceral leishmaniasis caused by L. donovani or L. infantum occurs in the Mediterranean littorals, the Middle East and adjacent parts of the USSR, the Sudan, East Africa, the Indian subcontinent and China, and South America ('L. chagasV). An arid warm environment provides ideal ecological conditions for the breeding of many species of sandflies. Kala-azar is commonly associated with dry, rocky hill country.
Photo 1. Termite hill association. In East Africa kala-azar is associated with dwellings situated near large termite hills. The vectors become infected by biting rodents which live in the holes in the termite hills, and later transmit the disease to people living in the vicinity.
Photo 2. Reservoirs of kala-azar. The photograph shows blood being collected from a dog for serological detection of kala-azar. Man is the only reservoir in India but elsewhere kala-azar is a zoonosis. Dogs, wild carnivores, and various species of rodents are commonly infected in rather focal fashion.
Photo 3. Clinical picture of kala-azar in Kenya. Increasing enlargement of the spleen and liver is a characteristic feature, while in dark complexioned subjects deepening skin pigmentation is seen - hence the synonym kala-azar, the 'black sickness'. A generalised lymphadenopathy is common in African kala-azar.
Photo 4. Temperature chart in kala-azar. The temperature chart shows a double peak every 24 hours. Despite the high temperature the patient often looks remarkably well and has a good appetite. A leucopenia with a relative lymphocytosis is often present.
Photo 5. Amastigotes of Leishmania in blood of experimental rodent. The blood picture is highly suggestive, comprising a marked granulopenia, moderate to severe anaemia without any special features and a very high ESR. Thrombocytopenia may lead to haemorrhagic manifestations. Occasionally amastigotes are seen in circulating macrophages. (x900)
Photo 6. Infantile kala-azar. Children present with irregular fever, anaemia, a moderately enlarged, non-tender liver, and a greatly enlarged firm spleen.
Photo 7. Post kala-azar dermal leishmanoid (PKDL). This syndrome is a sequel to visceral leishmaniasis following treatment. Dermal lesions which vary in appearance contain amastigotes in large numbers. Some start as hypopigmented macules. The lesions are highly infectious to sandflies.
Photo 8. PKDL in a Chinese patient. The patient was completely cured by chemotherapy. This response differentiates the condition from the anergic 'diffusa' type of leishmaniasis (210-212).
Photo 9. Smear of bone marrow. The prime means of diagnosis is the detection of amastigotes in bone-marrow, spleen or blood. They are recognised in dried smears of material stained by Giemsa's method by their characteristic morphology. While typically found in macrophages, isolated extracellular amastigotes are commonly seen in such preparations. (x 900)
Photo 10. Diagnosis by animal inoculation. The parasites may be isolated by intrasplenic inoculation into hamsters. After four to six weeks characteristic visceral lesions are seen macroscopically, and amastigotes are found in large numbers in smears of the liver and spleen. Picture taken at autopsy.
Photo 11. Promastigotes in NNN culture. After inoculation of aspirated material into a special blood agar medium (NNN medium, ie Novy-Nicolle-MacNeal) and incubation at 28°C for one to four weeks promastigotes may appear. L. donovani is more readily isolated in culture than L. infantum.(x 900)
Photo 12. Serum proteins before and after treatment of kala-azar. Large quantities of IgG are produced by patients with kala-azar and the A/G ratio is reversed. This may be demonstrated by electrophoresis (187a), or by simple tests such as the addition to serum of a drop of 30% formalin. The formation of a gel demonstrates the presence of a high proportion of globulin (formol-gel test) (187b).
Photo 13. Serum proteins before and after treatment of kala-azar(formol-gel test).
Photo 14. Immunofluorescence of L. donovani amastigotes. Only a small proportion of the increased IgG is specific anti-leishmanial antibody. The IgG can be demonstrated by the fluorescent antibody test using cultured promastigotes of L. donovani or tissue smears with amastigotes. The CFT becomes positive later than the FAT. (X1250)
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