It's A Blistering Bacteria Summer.

Tiny Organisms Are Having A Great Summer. We Are Not.

Photo by Arno Senoner on Unsplash

It’s hot out, and the bugs are thriving.

Three stories broke this month, in three states, with three different causes. First, a lung infection spreading through rooftop air conditioning in Manhattan. Next, a drug-resistant bug tied to a Meta data center’s cooling system in Wyoming. Finally, a parasite on produce across 34 states causing explosive diarrhea.

On paper, they don’t have much to do with each other. But look closer, and they’re all the same story wearing a different hat—warm water sitting somewhere it shouldn’t and little organisms growing when nobody’s watching closely enough.

The Cooling Towers of Manhattan

Let’s start on the Upper East Side in New York City where officials just spent the last two weeks chasing an invisible enemy through the air conditioning.

As of this week, health officials have confirmed dozens of Legionnaires’ disease cases tied to a cluster of buildings that includes the Guggenheim, a Whole Foods, doctors’ offices, and plenty of apartment buildings where people just wanted a normal July.

The timeline moved fast once it started. On July 2, the health department identified two Legionnaires’ cases close enough together to launch an investigation in Carnegie Hill and Yorkville. By July 5, a third zip code was added. As of July 9, the official count stood at 46 diagnosed cases—22 still hospitalized, 19 recovering at home, five never hospitalized at all. No deaths, this time.

This cluster follows a Legionnaires’ outbreak in Central Harlem last summer that sickened more than 100 people and killed seven. The Upper East Side got off easier, at least so far, in part because of how fast the city moved this round.

Legionella doesn’t come out of your tap. It grows in warm, stagnant water—the kind that collects in industrial cooling towers, the giant rooftop units that keep big buildings cool in the summer. When those towers aren’t maintained properly, they can turn into a mist machine for bacteria.

The city sampled more than 180 cooling towers across the affected zip codes and 31 came back positive on initial screening. Nineteen of those buildings had fully cleaned and disinfected their towers by July 10; the rest were ordered to finish by the next day.

But “positive” doesn’t mean “guilty,” and this is where it gets murky.

The screening test the city uses can detect Legionella DNA, but it can’t tell live bacteria from dead ones, and only live bacteria make anyone sick. The test that actually answers that question, a culture test, takes up to two weeks to come back.

The city is disinfecting first and confirming later, which is the opposite order of how it usually goes. Historically, cities wait for confirmation before spending the money and shutting things down. This time, every building with a positive screen got ordered to clean immediately, before knowing for certain whether that particular tower ever held a live, infectious bacterium.

Give credit where it’s due: releasing the actual addresses while the investigation is still open is new. City health departments don’t usually name buildings mid-investigation. They wait for certainty, which can take weeks. This time, the public got the list before the science was finished, which is a real change in posture, even if the source itself is still unconfirmed.

More About Legionnaires’ Disease

Legionnaires’ disease is a serious form of pneumonia caused by Legionella bacteria, which naturally occur in water. Most people exposed to the bacteria do not become sick. People develop Legionnaires’ disease by breathing in small droplets of water containing live Legionella bacteria. The disease is not spread person to person.

Symptoms typically develop two to 14 days after exposure and include fever, chills, muscle aches, shortness of breath, and cough. Legionnaires’ disease can be effectively treated with antibiotics when diagnosed early.

Anyone who lives, works or has visited the affected area since late June and develops flu-like symptoms should contact a health care provider immediately. People at an increased risk include adults age 50 and older, people who smoke or vape, those with chronic lung disease, people with weakened immune systems and those taking medication that suppresses the immune system.

Photo by Martin Podsiad on Unsplash

The Bacteria Nobody Ordered in Wyoming

Next in Cheyenne, Wyoming, a rare, drug-resistant bacterium turned up in the city’s water reclamation system, the reused water that irrigates lawns and supports industry, not the water anyone drinks.

The city’s utility board found it back in February during a routine sampling of its reclaimed water irrigation system. Residents didn’t learn about this issue until July.

After months of testing, officials discovered the source was Fortis Construction, a Meta contractor tasked with building a 715,000-square-foot data center known as “Project Cosmo” in southeast Wyoming outside the state’s capital.

So, the source traced back to a contractor testing the cooling systems for Meta’s massive new data center, which is the same basic engineering problem as those Manhattan rooftops, just scaled up to a server farm.

Cooling loops get flushed and tested before the machines go live, and this time, that test water carried bacteria you’d expect to find around industrial metal processing, not a reclamation plant in the High Plains.

Cupriavidus gilardii is known for its high resistance to metals, and research indicates that while infections are extremely rare, the bacterium may pose health risks to immunocompromised individuals and the elderly through direct exposure. To date, only a limited number of documented human infections have been reported worldwide.

When residents started asking questions, the mayor’s response was to suggest people were getting “caught up in the emotion of this,” which is a sentence I doubt will age well.

In addition, no one can say for certain what else was in that discharge, because, as one water researcher put it plainly, nobody required the kind of pilot testing you’d expect before new industrial systems get anywhere near a public water supply.

Let me just say that “trust us” is not a treatment plan.

I’ve heard this excuse before. Pacific Gas & Electric told residents in Hinkley the chromium was safe. Meta says an independent study found no impact.

Data centers are popping up across this country faster than anyone can regulate them, chasing cheap land, cheap power, and thirsty rivers.

Wyoming’s constitution all but guarantees new water rights get approved. Cheyenne’s mayor says the city needs the revenue. And yes, small towns get squeezed into these deals because they need the money or the jobs, and the company on the other side of the table has more lawyers than the city has employees.

Cheyenne’s Board of Public Utilities is now requiring separate storage tanks so cooling water never touches the sewer system again. That’s a good fix. It’s also a fix that should have existed before a rare bacterium ended up in the reclamation plant, not after four months of residents wondering why the reuse water got shut off and nobody would say why.

And now, with the company named and the violation notice issued, the answers keep running out.

One person wrote to me saying:

I’ve been digging through months of Cheyenne City Council, Planning Commission, and BOPU records.

What I found is that this wasn’t just a wastewater incident. BOPU revoked the Meta contractor’s sewer discharge privileges on March 24, but the public wasn’t told until late June.

During those four months, the City Council:

• amended the same wastewater code section the contractor was later cited for violating

• held a federally required public comment period that received zero comments because no one knew there had been a contamination incident

• continued approving major data center projects while repeatedly reassuring the public about water and environmental protections.

Yikes! Residents still don’t know where the contaminated wastewater was hauled after it was cut off from the sewer system.

Read more about what happened here.

Photo by Qeis Ismail on Unsplash

The Salad Nobody Can Trace

And then there’s the lettuce.

Now technically this story is about a parasite, not a bacterium, but it is a microscopic organism that can cause illness. Cyclospora is a single-celled parasite that requires a host to complete its life cycle and reproduce, unlike bacteria, which can survive and multiply independently in soil, water, or the body. We liked the title so we went with it!

A Cyclosporiasis outbreak—the illness caused by Cyclospora, the parasite known for triggering “explosive,” relentless diarrhea—has now been reported in 34 states, with Michigan alone logging more than 3,300 cases in a state that usually sees about 40 or 50 cases a year. Health officials still haven’t found the source.

“Early information has shown lettuce as a common product that regularly comes up during the investigation,” said Dr. Natasha Bagdasarian, chief medical executive at the Michigan Department of Health and Human Services (MDHHS) in a statement.

Past outbreaks have been traced to basil, cilantro, mesclun mixes, raspberries, and snow peas. All types of produce that passes through a lot of hands and a lot of water before it lands on your plate. This one’s still a bit of a mystery, weeks in.

Food picks up the parasite typically through water supplies that are infected with human feces.

Cyclospora is a parasite that infects the intestines and causes watery diarrhea, nausea, and stomach cramps. It is often contracted by eating or drinking something contaminated with the parasite.

It doesn’t rinse off easily. You basically have to cook it to death, which isn’t exactly the advice anyone wants to hear about their salad in July.

The timing between becoming infected and becoming sick is usually about one week but can range from 2 days to 2 weeks or more.

Cyclospora was one of multiple parasites made optional to track by the Centers for Disease Control and Prevention (CDC) last year, according to the agency's website.

In July 2025, the CDC reduced the number of pathogens tracked by the Foodborne Diseases Active Surveillance Network, known as FoodNet, from eight to two. FoodNet is a CDC collaboration with the U.S. Department of Agriculture, the Food and Drug Administration and 10 state health departments.

The CDC noted on its website last week that it would be publishing data more frequently than in previous seasons given “the recent increase in cyclosporiasis cases.”

It's worth noting that federal law already requires farms to provide toilets and handwashing stations for crews working more than three hours a day, but that threshold is itself a loophole, and research has tied inadequate field sanitation directly to higher rates of intestinal parasites among farmworkers. The fix isn’t complicated. It’s enforcement.

The Common Connection

None of these outbreaks are the same disease, the same industry, or even the same kind of water.

A cooling tower, a data center’s cooling loop, and fields irrigated with who-knows-what. These places are where warm water sits, tiny organisms multiply, and testing is either an afterthought or a legal minimum instead of a real safeguard.

In each story, the public is dealing with the health consequences.

The epidemic here is not any single bacterium, but the lag time between “we knew” and “you knew.”

Every summer, as the heat goes up, all of it comes due at once.

We Can Make Changes To Protect Our Health

Cooling towers: Require every tower to register with the city and test for Legionella on a set schedule with results made public not just after someone gets sick. NYC has had this rule since its 2015 South Bronx outbreak, which is part of why officials could move fast this time.

Data center cooling systems: Require pre-operational testing of discharge water before a facility goes live and offer separate storage units so cooling water never touches public wastewater systems.

Produce traceability: This problem is mostly a federal issue, but cities and states can push for faster public alerts the moment a source starts narrowing, instead of waiting for FDA confirmation.

Farmworker sanitation: Close the loophole that lets employers skip toilets and handwashing stations for shifts under three hours, and enforce the existing ban on towelette substitutes for real soap and water. Intestinal parasites like Cyclospora have long been linked to inadequate field sanitation. The fix already exists, and it just needs enforcement teeth.

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Who remembers Banarama? Doesn’t it feel more and more like we’re all being left on our own to figure out these problems?

What’s happening in your town or city? Do you feel safe? Let us know in the comments.