Occurrence of Leishmania major in sandfly urine.

Promastigotes of Leishmania major were frequently detected in the urine droplets discharged by infected Phlebotomus papatasi and P. duboscqui females during feeding. Parasites were present in the urine of 37.5% P. papatasi and 16.1% P. duboscqi females, even in those with low intensity gut infections. Free-swimming forms (elongated nectomonads, short slender promastigotes and metacyclic forms) predominated in excreted droplets. Viability of excreted parasites was proved by cultivation on blood agar, and the presence of metacyclic forms in urine droplets was confirmed by specific fluorescence assay with 3F12 antibodies. While the release of promatigotes from the anus of the sandfly was frequent, these were rarely egested from the mouth-parts of sandfly females (1.3% for P. duboscqi and 0% for P. papatasi) fed on microcapillaries, even if the females were heavily infected. The possible role and significance of the discharge of parasites in sandfly urine are discussed.