(left) The electrodisinfection micro-focusing unit. (right) Jane Taylor-Flemons and the power source for the 20, 000 litre/day electrodisinfection unit.

Cryptosporidium is one of the most difficult infectious agents to neutralise in water supplies. It is a parasite that infects by forming a “feeder” attachment to the intestinal (gut) cells of its host (eg humans). Its sporozoites (eggs) hatch from its oocyst (shell) and form this attachment via a feeder organelle. Only 1-10 Cryptosporidium are required for infection; exposing the elderly, babies and immuno-compromised patients to serious risk of illness and even death.

Our exhaustive exploration of the large biological and electrodisinfection parameter landscape included phase-contrast video-microscopy at high magnification of Cryptosporidium oocysts and sporozoites after electroporation and boiling treatments. The morphological parameter that exhibited the most profound change after boiling was the apical-distal (AD) distance between the apex of the “feeder” organelle and the posterior of the sporozoite. Electroporation treatments at 4 kHz (focused field strength ~7.8 x 106 V/m) produced a more pronounced reduction in the AD distance than that produced by boiling, the recommended treatment for neutralising drinking water during the recent Cryptosporidium outbreak in Sydney.

This research highlights the need of a definitive test of the infectivity potential of Cryptosporidium for properly evaluating even the more commonly acceptable disinfection treatments such as boiling.

Hans Coster, Virginia Shepherd,
Jane Taylor-Flemons, Lutz Gaedt,
Leonard Coster and Terry Chilcott