Cryptosporidiosis outbreak associated with McMenamins Anderson School Pool in Bothell

Summary

Public Health investigated an outbreak of cryptosporidiosis (crypto) associated with spending time in the pool at McMenamins Anderson School (McMenamins) in Bothell. Crypto is caused by the highly contagious parasite Cryptosporidium, which most often causes watery diarrhea, but sometimes people do not experience any symptoms.

We suspect this illness spread because someone infected with Cryptosporidium spent time in the pool and spread germs that infected other people.

Public Health determined that the pool at McMenamins is well-maintained and the facility follows King County’s health and safety requirements. Even in a very well-maintained swimming pool, Cryptosporidium is very resistant to chlorine, so if someone infected with Cryptosporidium uses the pool, the parasite can survive for several days.

The best way to prevent illness is for people to stay out of pools if they have had diarrhea or vomiting in the past two weeks. People should also shower with soap before getting into a pool.

This outbreak appears to be over, and our investigation is complete.

About Cryptosporidium

• Cryptosporidium (crypto) is a microscopic germ (parasite) that causes watery diarrhea and other stomach problems
• Crypto is very common, with over 800,000 cases in the U.S. each year
• People most commonly get infected with Cryptosporidium by:
• Swallowing contaminated water, often from pools or lakes
• Swallowing contaminated drinks, including water or ice
• Eating contaminated food
• Touching their mouth with contaminated hands after changing diapers, caring for an infection person or animal, or touching contaminated objects
• Putting a contaminated object in their mouth
• Symptoms can include:
• Watery diarrhea (often frequent and prolonged)
• Stomach cramps or pain
• Nausea
• Vomiting
• Fever
• Weight loss
• Dehydration

Symptoms usually begin within 2–12 days after swallowing Cryptosporidium and often go away within 2–3 weeks. However, symptoms can persist for up to 30 days.

How to protect yourself from Cryptosporidium and other germs when in a public pool

• Don't go in a pool if you're sick. If you have been sick, it is recommended to wait at least two weeks after your symptoms have completely stopped before using a public pool. Even if a person no longer has symptoms, they can still spread harmful germs that get other people sick.
• Infants and small children need to wear a tight-fitting swim diaper.
• Take a shower with soap before entering the pool.
• Don't intentionally swallow a lot of pool water as it increases the chance of swallowing germs.
• If you see an issue, such as poop in the pool, notify the pool staff immediately.
• If you think you got sick from using a pool, spa, or other regulated recreational water facility (not beaches) contact 206-263-9566 or submit a complaint online at: King County's Public Health Service Request Access. Please note that you need to select, "Don't see what you're looking for? Create a new request," then scroll to "Water Rec Facility Complaint" in the "Request Type" box.

Illnesses

Fourteen people reported becoming sick after swimming in the McMenamins pool on August 29 or August 30, 2026. They reported symptoms such as nausea, diarrhea, abdominal cramps, and fever.

Public Health actions

We interviewed six people who became sick to learn more about their symptoms and what may have caused their illnesses.
On September 21, we visited the pool facility and did not find any violations.

We reviewed fecal incidents because fecal-contaminated pool water can spread Cryptosporidium. The facility operator did not record any fecal incidents on August 29, 2026 or the 10 days prior.

We reviewed with the facility operator Cryptosporidium education and how to safely clean up fecal incidents in swimming pools. We also reminded the operator about the rule that guests are not allowed to enter the pool if they had any vomiting or diarrhea within the past two weeks.

Laboratory testing

Laboratory testing was performed for five individuals who were exhibiting symptoms after spending time in the McMenamins pool on August 29, 2026 or August 30, 2026. Four were diagnosed with Cryptosporidium.

More information about Cryptosporidium

• About Cryptosporidium, Centers for Disease Control and Prevention (CDC)
• What is Cryptosporidiosis?, Cleveland Clinic