English Abstract Cryptosporidium and Giardia are parasitic protozoa that
can be transmitted to man by drinking and recreational water. Depending on
the immune state of the infected host, they can cause a selflimiting to
severe gastro-enteritis. This report gives a review on the potential for
transmission of Cryptosporidium and Giardia by drinking and recreational
water, attending data on the occurrence of these parasites in humans and
other reservoirs, their persence in sewage and surfase water, removel of the
(oo)cysts by water purification processes and waterborne outbreaks. This
report also describes the resultsof a preliminary study on the presence of
Cryptosporidium and Giardia at Dutch water supplies.