Thanks for the information, Tom. I neglected to mention that purification is accomplished in less than 1 minute according to the company. Do you feel that the C. Parvo oocysts are common enough to render use of the Steri-Pen alone a hazardous practice ? What are the symptoms and prognosis for C. Parvo infection ? The simplicity of the device and its use as well as its size make it a serious consideration for me. Thanks.