Diurnal periodicity of Leishmania amastigotes in peripheral blood of Indian Kala-azar patients.

Peripheral blood smears of 20 patients with Indian Kala-azar (KA) were collected throughout the day and night and examined for presence of Leishmania amastigotes. Amastigotes were detected in 46% of peripheral blood samples taken during the day (08:00-17:00 h) and 66% and during the night (18:00-07:00 h). This difference was statistically highly significant (P < 0.0001). The confirmation of amastigote diurnal periodicity is of interest, and the high percentage of parasitemic patients at night is likely to reflect the biting habit of the sandfly vector of Kala-azar Phlebotomus argentipes.