Chlorine can address common bacteria including E. Coli in minutes to hours, but Crypto can last 10 days.
According to a The CDC’s latest report outlining outbreaks of illness released today, Clapway reports. The parasite has a resistant outer shell that allows it to combat chlorine treatment. The parasite, Cryptosporidium (commonly called “Crypto”) is passed through stool, and can lead to symptoms including dehydration, vomiting, and diarrhea, lasting on average 7 days, but can persist up to 4 or more weeks. The immune compromised can suffer more serious disease. The CDC report says 52% of recreational water incidents in the 2011-2012 reporting period (the most recent compiled) were due to Crypto, and “continues to the dominant etiology of recreational water-associated outbreaks”
Swimmers may have contacted the parasite outside and brought it to the pool, and advises parents to take kids on regular bathroom breaks and check diapers away from the poolside area. Michele Hiavsa, chief of the CDC Healthy Swimming Program, warns “With these outbreaks, we see they disproportionately affect young children”, according to this report by ABC news. The CDC’s guide to Healthy Swimming can be viewed here. Hiavsa also advises swimmers to check on how well their local pools are managing treatments.