Up to a thousand pool and spa users annually suffer the nasty sickness and diarrhoea illness, cryptosporidiosis.
Outbreaks occur when the gut-living Cryptosporidium oocysts responsible are not killed by normal disinfectant levels. Just one oocyst can infect, and millions are released if diarrhoea from a sufferer gets into the pool. You firstly guard against Cryptosporidium with good plant. Proper filtration – low or medium-rate and with coagulation – is the key to removing oocysts. But not all oocysts will be removed in a single pass of pool water through the filters, however good the pool’s water circulation. So a number of passes are necessary, and the pool will have to be closed if infestation is suspected. Secondary disinfection (UV or ozone) also helps. Spas, of course, can be emptied and disinfected if there’s an accident.
The next port of call for cryptosporidium prevention is good hygiene . Tell users not to use the pool or spa when they have diarrhoea, or for 48 hours after symptoms stop. If they have had cryptosporidiosis, they must extend that to a fortnight after symptoms stop. If an outbreak of cryptosporidiosis has been identified, it may be that some regular bathers will have had diarrhoea, but not had the illness diagnosed. They too should be excluded from using the pool for a fortnight after symptoms have stopped.
There are other, important, routine safeguards:
• Encourage parents to take children to the loo before swimming and offer them frequent toilet breaks.
• Make sure handwashing and nappy disposal facilities are adequate and that proper swim nappies are used by babies and toddlers
• Maintain implement a clear policy for recognising, reporting and dealing with faecal accidents. Occasionally water companies are affected by adverse circumstances resulting in an increased risk that Cryptosporidium oocysts get into the water supply. Water companies may then advise domestic customers to boil water for drinking and food preparation. This happened throughout August in Lancashire.
Generally, in a well-designed and operated swimming pool or spa – following PWTAG guidelines on turnover, filtration, disinfection etc – the risk to public health should be low and no special action will be required. In these circumstances pool operators should also receive advice from the multi-agency incident team, issued via the water company to its business customers. It is particularly important for pools which don’t routinely operate to PWTAG standards to follow this advice.