UV Disinfection Provides Protection Against Cryptosporidium

Ultraviolet (UV) light is increasingly being used as an effective barrier for Cryptosporidium and other emerging chlorine resistant organisms in the United Kingdom.  Many leisure operators are now installing UV systems as standard to ensure their water does not pose a risk to public health. This article examines the dangers posed by Cryptosporidium and how Ultraviolet disinfection can minimize the risk of an outbreak.

Understanding the problem

Found in water supplies all over the globe, Cryptosporidium outbreaks are now becoming more and more frequent causing severe illness that can be fatal to vulnerable groups such as the young and elderly and in a number of cases has lead to costly and drawn out legal action. 

The problem is, whilst disinfection with chlorine effectively destroys other pathogens - it takes less than one minute to eradicate E. coli, and approximately 16 minutes to kill the Hepatitis A virus - cryptosporidium is virtually immune.  Due to a thick outer membrane, it takes more than 10 days to destroy cryptosporidium in a normal pool (25 degrees with free chlorine levels of 1ppm, a pH of 7.5 and no chlorine stabilisers) according to the U.S. Centre of Disease Control.

The most common forms of the pathogen are Cryptosporidium C. homius or Cryptosporidium paravum, commonly found in livestock.  Both cause severe gastrointestinal symptoms in humans, including diarrhea, stomach cramps, vomiting and nausea, which can lead to fever and excessive dehydration.  Infections typically last between one and two weeks, but some e.g. those with a weaker immune system such as the very old or the very young, may develop more severe or chronic symptoms leading fatalities.

Cryptosporidium propagates itself by using its host to spread oocysts (eggs) that then infect others. These oocysts latch onto cells in the intestinal tract, where the parasite reproduces. It then exits the body through the stool ready to infect another person.  In swimming pools, cryptosporidium is generally spread via diarrhea (accidents), which release millions of crypto oocysts into a pool environment from a single fecal incident.  As it only takes 10 to 30 occysts to become infected, simple bad hygiene such as not washing hands after using the toilet or changing a nappy can easily cause an outbreak.

Minimising the risks

The most significant step any leisure operator can take to avoid an outbreak of Cryptosporidium is education.  By informing users of the risks and the action that they can take, such as showering before entering the pool, washing their hands after using the toilet and avoiding pool use during and after periods of sickness, operators can vastly reduce the risk of introducing Cryptosporidium into the pool environment.  However, no amount of education will protect users from outbreak once pool water becomes infected.         

Considered the best technology to achieve protection, Ultraviolet disinfection systems are now being used widely as an effective barrier to safeguard against all known bacteria, viruses and pathogens, including the seventeen Chlorine resistant organisms that threaten pool user safety such as Cryptosporidium and Giardia.  

When properly applied, UV light at wavelengths of 254 nm (known as UVC light) is absorbed by the DNA and permanent damage is caused.  Once exposed to UVC light, the DNA quickly stops normal cell functions, rendering the organism non viable.  Replication is prevented and the organism quickly dies. No species have demonstrated an ability to become resistant to UV, unlike chemical disinfectants where a growing number of organisms have become increasingly tolerant.

Case Study - New York

Due to the resistant nature of Cryptosporidium and the scale of health problems caused, the need for increased protection was forced to the top of the agenda, when over 4000 patrons of multiple aquatic facilities in New York became seriously infected with Cryptosporidium, and consequently took out legal action.

The outbreak was tracked to a splash pad feature at one of New York's leading water parks where traditional methods of treatment had failed to provide adequate protection.  So large was the scale of the problem, the New York Department of Health decided to re-think their entire water treatment strategy. Calling upon their experience in the drinking water industry to find a solution to this growing threat, they concluded that the risk of an outbreak could be greatly reduced by the use of "Ultraviolet water treatment systems."

Working closely with atg UV Technology, the New York Department of Health invested in a range of state-of-the-art UV treatment systems to safeguard public health.  Additionally, atg UV biodose tested a number of the UV systems, gaining regulatory approval for their effectiveness against Cryptosporidium and other water borne pathogens.

Ultimately the inclusion of UV treatment systems is now firmly entrenched within New York's water safety legislation for range of leisure facilities.  A decision already being investigated and adopted by forward thinking companies in the UK leisure industry keen to avoid the costly ramifications associated with an outbreak.

Section 6-3.11 section 3 of the New York water safety regulation states:-

"Ultraviolet light disinfection is required in addition to an approved Chemical disinfectant."