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May 9, 2011 / in Blog Articles

More than 2000 resisdents of Ostersund, Sweden became sick after drinking municipal water contaminated by Cryptosporidium. The disease-carrying protzoan Cryptosporidium gained public notoriety during the cryptosporidiosis outbreak in 1993 when thousands of Milwaukee resisdents were affected resulting in excess of 100 fatalities.The likely cause of that epidemic was sewage discharged from one of Milwaukess’s wastewater plants that was able to enter the drinking water plant intake. Cysts passed through the coagulation and filtration steps and were not inactivated because they are very resistant to chlorine disenfectant.Cryptosporidium is a protozoan parasite that can cause a gastrointestinal illness called cryptospoidiosis. The oocyst form of the parasite is protected by an outer shell that allows it to survive outside a mamallian host for long periods of time. The oocysts live in humans and animal intestines where they multiply and are excreted in feces in the form of dormant, thick-walled oocyst, or fertilized egg. The parasite occurs in every region on Earth. The primary symptom of cryptosporidiosis is diarrhea, symptoms usually appear within 2-10 days after infection and rarely last more than 2 weeks. Cryptosporidiosis may be fatal to persons with sigificant immune deficiency.Why is Cryptosporidim parvum resistant to chlorine? Chlorine triggers a strong defensive molecular response to oxidative stress in the waterborne parasite according to an article in the journal Applied and Environmental Microbiology. This response likely contributes to the high resistance of these waterborne pathogens to chlorination. These findings will assist in the development of more efficient disinfection protocols and analytical methods for the inactivation of chlorine-resistant micro organisms.If it happens in the United States and Sweden then you know it can happen in South Africa. Because here in South Africa the problem of untreated, or semi-treated sewage spilling from Waste Water Treatment Works, was becoming a national problem. It has been claimed that only 32 out of approximately 970 water treatment plants around the country complied with the requirements for the safe discharge of sewage. That’s a compliance level of only 3%, and as a consequence South Africa’s rivers and coastal waters are becoming increasingly polluted, posing a danger to human health, as well as the environment.One of the best ways for municipalities to treat waste water in order to inactivate Cryptosporidium is the use of ultraviolet light treatment at relatively low does. And then for houshold use the use of silver impregnated ceramic filter cartridges is recommended.