What Is Cryptosporidiosis (Crypto) and What Symptoms Does It Cause?

Cryptosporidiosis (commonly called crypto) is an illness caused by the highly contagious parasite Cryptosporidium. The Bellevue Reporter's coverage of a crypto outbreak linked to a Bothell pool notes that it often causes watery diarrhea. If you swam in an affected pool or have persistent watery diarrhea, the key facts below can help you understand what crypto is, how it spreads, and what to watch for.

What causes crypto?

Crypto is caused by Cryptosporidium, a parasite described in the Bellevue Reporter report as "highly contagious." The parasite infects the intestine and leads to the diarrheal illness known as cryptosporidiosis.

Because it is highly contagious, crypto can spread quickly in shared water settings — which is why pool-associated outbreaks, like the one reported in Bothell, are a recognized pattern.

What are the main symptoms?

The symptom highlighted in the Bellevue Reporter's report is watery diarrhea. That is the hallmark sign of crypto, and it is often the reason people seek information after a possible exposure.

If you are trying to judge your own risk, the most relevant signal is whether you have watery diarrhea after a likely exposure — for example, swimming in a pool connected to a known outbreak.

How does crypto spread?

Crypto spreads through contaminated water, including pools. That means:

• Swimming in water contaminated with the parasite
• Swallowing water while swimming
• Being in a pool that an infected person has used

The Bothell pool outbreak is a concrete example of this waterborne route: a shared pool setting where the parasite reached multiple people.

Who should pay attention to this?

You may want to take this seriously if either of the following applies:

• You visited an affected pool — such as the Bothell pool named in the outbreak coverage.
• You have symptoms consistent with crypto — particularly watery diarrhea.

The combination of a known exposure and watery diarrhea is the situation where this information is most useful.

What to do next

If you think you were exposed or you have ongoing watery diarrhea, the practical step is to seek medical guidance rather than self-diagnose. A healthcare provider can assess your symptoms and determine whether testing is appropriate.

Because crypto is highly contagious and spreads through water, avoiding swimming while you have diarrhea helps prevent passing the parasite to others in shared pools.