Cryptosporidium outbreak linked to Bothell indoor pool

Public Health Seattle-King County investigated illness associated with the McMenamins Anderson School indoor pool in Bothell after exposure on August 29 and 30, 2026. The investigation suspected that one infected swimmer introduced the parasite, which then spread to other people. [1][2][3]

The investigation associated the exposure with 14 cases. Laboratory testing was performed on five symptomatic people who had been at the pool during the exposure period, and four received a cryptosporidiosis diagnosis. [1][2][3]

The health investigation found that the pool was well-maintained and that the facility followed King County health and safety requirements. That finding does not rule out transmission because the parasite can resist chlorine treatment. [1][2][3]

The illness is cryptosporidiosis, commonly called crypto. The reported exposure occurred in August, while Public Health Seattle-King County announced the investigation on September 30, so the announcement does not establish that transmission is still continuing. [1][2][3]