What is Cryptosporidium and Cryptospirosis?
United Utilities recently found traces of cryptosporidium at a water treatment works in Lancashire, leading to boil water notices for thousands of consumers. Although high impact and widely publicised, the event is relatively low risk for contracting an illness.
Only about 15% of cases of Cryptospirosis (the illness caused by cryptosporidium) are contracted through drinking water consumption. The majority are from swimming and contact with animals. Food accounts for a very low percentage of the total but has the potential for huge liability if an outbreak occurs from prepared foods.
Cryptosporidium is a protozoan parasite that multiplies in the gut of humans and other animals. The life cycle stage that is shed in faeces is called an oocyst. People become infected when they swallow oocysts; one single oocyst is enough to make someone ill with cryptosporidiosis.
Cryptosporidiosis is the illness caused by Cryptosporidium and it generally takes the form of watery diarrhoea with abdominal pain. Cryptosporidiosis is especially common in young children but anybody can get it.
Ingestion of oocysts can occur when in close contact with an infected person or animal and their faeces, through eating contaminated food, or through swallowing contaminated water. Most people become ill 4 to 7 days after ingesting oocysts, and the illness can last up to 2 weeks. Some people with weakened immune systems can have serious, possibly life-threatening Cryptospirosis.
The Cryptosporidium oocyst is resistant to chemicals used in water disinfection and is normally removed by filtration after coagulation. When filters are breached in drinking water treatment plants, Cryptosporidium is occasionally detected downstream. The compromised filter is normally rectified rapidly and after several clear samples the boil water notice is lifted.
In swimming pools, faecal contamination of the pool will often overwhelm the treatment, and the filters can take several hours to make the pool safe. This can lead to the evacuation of swimming pools. A single infected bather can introduce over 150 million oocysts to the pool which, if evenly distributed, would be more than enough to spread the infection to other bathers (figures from the Pool Water Treatment Advisory Group 2015). This can be a particular problem with infants in swimming pools, as they are more susceptible to the illness and have limited bowel control.
In critical applications, such as hospitals and food production, local filtration to remove Cryptosporidium is sometimes used. For immunocompromised patients, bottled sterile water, or water filtered at the point of use, is generally used for drinking.
Clearwater can help your organisation to avoid a Cryptosporidium outbreak in your pool, hospital or food production line. We supply a range of services from consultancy, sampling and risk assessment to plant options such as filtration, coagulation and disinfection. Contact your local Clearwater office for more information.