THE PRESENCE OF GIARDIA AND CRYPTOSPORIDIUM IN SURFACE WATERS AND EFFLUENTS IN ISRAEL

During a period of 9 months (May 1995-January 1996), various environme ntal sources were investigated for the presence of Giardia and Cryptos poridium in Israel. Out of 15 samples from five streams, 12 were posit ive for Cyyptosporidium (80%) with an average concentration of 0.04-1. 9 oocysts/l and 8 were positive for Giardia (53.3%) with 0.05-0.78 cys ts/l. Two springs were also tested and found positive for Cryptosporid ium and (0.54 oocysts/l) only. The main drinking water reservoir of Is rael, Lake Kineret, was also sampled 6 times at two sites. Cryptospori dium was isolated in 4/6 samples (66.6%) at an average concentration o f 0.3-1.09 oocysts/l while Giardia was present in 5/6 samples (83.3%), 0.135-16.2 cysts/l. Drinking water entering a filtration pilot plant was also tested and found positive for Cryptosporidium in 23/35 sample s (0-317 oocysts/l) and 8/35 for Giardia (0-16.7 cysts/l). In order to I:valuate some potential inputs of contamination of the drinking wate r sources, two possible contributors were tested: domestic sewage and cowshed effluents. In sewage effluents, 3/3 samples were positive fur both Cryptosporidium and Giardia. The oocysts and cysts were present a t 8.3-8.05/l and 5-27.3/l respectively. In cowshed effluents, 1/6 samp les was positive for Cryptosporidium at a high concentration (3,630 oo cysts/l) but no Giardia cysts were found. The levels of Cryptosporidiu m and Giardia oocysts and cysts isolated from these environmental samp les may present a public health hazard although no major outbreaks hav e so far been reported in Israel. (C) 1997 IAWQ. Published by Elsevier Science Ltd.