Abstract
The leishmaniases are parasitic diseases that affect large populations in vast areas of the world (Desjeux, 2001). The causative agents of these diseases, protozoan parasites belonging to the genus Leishmania (Kinetoplastida: Trypanosomatidae), are transmitted by phlebotomine sand flies (Killick-Kendrick, 1999). In culture media (at 26–28 °C, pH 7.2), Leishmania parasites develop as motile promastigotes similar to those found in the sand fly midgut. A number of reports have shown that the addition of 1–5 % human urine stimulates growth, leading to more rapid multiplication and a higher concentration of parasites at the stationary phase (Ali et al., 1998; Armstrong & Patterson, 1994; Howard et al., 1991; Iqbal et al., 2006; Shamsuzzaman et al., 1999; Singh et al., 2000). Preliminary studies have indicated that the factor responsible for this enhancement is a small molecule which is not destroyed by autoclaving (Ali et al., 1998). However, despite the substantial advantages of using defined media for the culture of human pathogens (Schuster & Sullivan, 2002), the factor(s) in urine that is responsible for promoting growth of Leishmania has not been identified.
Preliminary experiments confirmed that the addition of 5 % (v/v) human urine to Leishmania major promastigotes cultured in RPMI 1640 enhanced the rate of multiplication about 10-fold (two-tailed t-test, P <0.005). The final concentration at stationary phase increased from 4.0x106 to almost 4.2x107 parasites ml–1. This exacerbative effect was not abolished by boiling the urine or treating it with proteinase K (Fig. 1).