Adequate water treatment is the cornerstone of modern public health, but few take a moment to ask why. Well, it’s pretty obvious—water is the elixir of life, and, while we ingest it for survival, it also transports disease. However, the exact biological means through which illness can emerge and spread through water varies, with some causes being rare and others finding near-ubiquity. One such example of the latter is Cryptosporidium.
Chlorine is often associated with water treatment practices, as disinfects microorganisms and other harmful pathogens. However, Cryptosporidium (or just Crypto) is resistant to chlorine. For this reason, it may emerge in drinking and recreational water, and those who ingest the parasitic microorganism can contract the disease cryptosporidiosis.
To make matters more worrisome, Crypto lives in the intestines of infected humans or animals, and they shed the germ via their stool. To contract Cryptosporidiosis, you need to ingest infected fecal matter. In the United States, there is an estimated 748,000 cases of cryptosporidiosis each year.
Cryptosporidium oocysts are notable for their outer shell, which protects them from chlorine disinfection and helps them survive outside the body for substantial periods. Many species are known to infect humans and animals, but the most common found in human beings are Cryptosporidium parvum and C. hominis.
Following infection with the parasite, symptoms of cryptosporidiosis begin after 2 to 10 days (average 7). For the most part, these symptoms aren’t life threatening. In fact, some people with Crypto demonstrate no symptoms at all. However, most experience watery diarrhea and related gastrointestinal issues, as well as a fever. These issues often last 1 to 2 weeks, but reoccurrence does sometimes happen for up to 30 days. For those with weakened immune systems, the illness can be serious and sometimes even fatal.
Precautionary actions at the individual level can limit one’s exposure to Crypto. The Centers for Disease Control and Prevention (CDC) advises care when potential exposure has taken place. Much of this is aligned with conventional efforts associated with human hygiene—washing hands after using the toilet, avoiding touching your mouth with contaminated hands, and being especially careful when at a higher risk for infection.
For limiting the spread of Crypto in recreational water, the CDC advises not to drink pool water. Furthermore, this is where that one seemingly strange habit becomes immensely important—showering before jumping in the pool. Showering be a useful way of preventing contamination of the pool water. If Crypto does make an unfortunate presence at a public pool, the CDC recommends closing and treating the water with high levels of chlorine, through hyperchlorination, to placate the outbreak.
While water is the primary means by which Cryptosporidium spreads, the protozoan can be transferred via infected food. By thoroughly washing any produce with uncontaminated water, individuals can help stifle parasite’s circulation.
However, fortunately for the public, while these precautionary efforts are important, they are generally the final, “just-to-be-safe” step in a series of mitigating tasks. Thankfully, the dependability of modern technology, guided by the helping hand of standardization, makes sure that Cryptosporidium is not as prevalent as it could be.
Cryptosporidium in Drinking Water
The big issue with Cryptosporidium and drinking water is that the parasite persists under normal chlorine levels. However, water treatment incorporates numerous tasks to guarantee the cleanliness of water before it reaches people’s homes. Ultraviolet microbiological water treatment systems, for example, make use of UV radiation to disinfect water supplies. This bactericidal treatment is enough to eliminate Crypto, as well as related microbes, like Giardia.
Crypto is also isolated from water through membrane filtration processes, such as microfiltration and ultrafiltration, due to the oocysts being wider than the pores of the membranes.
UV water treatment systems are addressed in NSF/ANSI 55-2017. Furthermore, guidelines for drinking water treatment units are covered in NSF/ANSI 53, and AWWA B110-09 details guidelines for membrane systems, including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, and electrodialysis membrane systems.
However, numerous other standards are used actively in the water treatment industry, encompassing the vast range of methods used to assure public health. Standard developing organizations devoted to this topic include NSF International and the American Water Works Association (AWWA).
Cryptosporidium in Public Pools
While the presence of fecal-borne parasites in our drinking water supply is beyond alarming, in the United States, there has been an increasing amount of Crypto outbreaks in public pools each year. In 2014, there were 16 outbreaks; this amount doubled to 32 in 2016.
The CDC advises a hyperchlorination process for 10.6 days in public pools that have been contaminated with Cryptosporidium. The presence of Crypto in the water can be determined by a method detailed in the international standard ISO 15553:2006.
There are additional standards for assuring clean water in public pools that have been published by the Association of Pool and Spa Professionals (APSP)., an ANSI-accredited standards developing organization. Since these standards were last published, APSP merged with the National Swimming Pool Foundation (NSPF) and became the Pool & Hot Tub Alliance (PHTA).
Cryptosporidium from Poor Food Sanitation
With certain foods, individuals can usually remove Cryptosporidium by thorough rinsing, but this is not always reliable. Crypto outbreaks tied to poor food sanitation still occur, with eleven confirmed cases of cryptosporidiosis being traced to a Pennsylvania rescue farm in 2017. In 2016, another occurrence saw 209 cases of the infection in central Ohio.
Quality management practices oriented towards detecting the presence of these protozoans can ease the potential for contamination. For example, ISO 18744:2016 details laboratory methods for the detection and enumeration of Cryptosporidium oocysts on fresh leafy green vegetables and berry fruits.
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