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Graphic by Nick Orabovic

In July 2007, Salt Lake Valley aquatics operators thought they were looking at a banner year. Record-breaking heat and plenty of sun had made local pools and waterparks the most popular hangouts around. Deck chairs were full. Swimmers were enjoying the water. Snack bars were doing brisk business. Things were looking good.

Then the calls started coming.

First, health officials reported just a few swimmers falling ill. Next, it was several dozen. By late August, the trickle had turned into a tsunami — nearly 2,000 swimmers had been sickened statewide. The culprit? A parasite known as cryptosporidium, or crypto, as it’s commonly called.

Before that summer, some Utah operators had only a vague understanding of crypto and its repercussions. Even today, some may be wondering what went wrong, and whether they can stop it from happening again.

“It started slow and then literally exploded,” recalls Linda Bogdanow, epidemiology supervisor of the Salt Lake Valley Health Department.

Martin Jensen also remembers it all too well. “Within a month’s time, a few reported cases turned into a literal epidemic. It was a leading news story throughout all of summer 2007,” says Jensen, marketing and public relations manager at Salt Lake County Parks and Recreation.

At the height of the outbreak, things got so bad, health officials took an extraordinary step: They banned all children under age 5 from public pools, including gyms and apartment buildings.

Luckily, that was around Labor Day. By then, children were returning to school and many outdoor public pools had shut their doors for the winter. As a result, the number of reported new cases began decreasing. The worst was over.

When the dust settled, Utah had experienced one of the nation’s largest cryptosporidium outbreaks ever linked to recreational water. Nearly 700 cases were confirmed in the Salt Lake Valley alone, with more than 1,900 reported statewide. Considering that only a fraction of all diarrheal illness cases are reported, it’s a certainty that the Utah outbreak affected many, many more, according to the Centers for Disease Control in Atlanta. There’s no way to get an exact number, but Bogdanow is confident that many more people got ill that summer than reports indicate.

“We were not expecting to see that,” she says. “That was the first time we’d experienced an outbreak that large.” Previously, the state averaged just 30 crypto reports annually, so it’s not surprising that Bogdanow and her colleagues were taken aback by the size and magnitude of the outbreak.

CDC officials were not. They have been warning of this type of incident ever since determining aquatic-related outbreaks were on a dramatic upswing. “It’s not time to hit the panic button, but it’s time to be proactive,” says Michele Hlavsa, CDC epidemiologist.

Given the statistics, though, some degree of panic is understandable. Since 2004, the number of pool-associated outbreaks has leapt 270 percent. According to the CDC, 2007 was the worst year yet. In that year alone, 26 outbreaks hit aquatics facilities and sickened more than 11,000 people — the population of a small town. Preliminary numbers indicate a slight decrease last year, but officials are again bracing for the worst in 2009.

Statistics are only part of the story. For operators, outbreaks leave a lingering effect that can jeopardize more than just their patrons’ health. Whenever someone gets sick, it can lead to costly litigation. A recent outbreak led to the first-ever class action lawsuit in aquatics history. Operators who avoid lawsuits still must survive the court of public opinion. Hundreds of sickened swimmers are hardly the best PR for pools and waterparks.

It isn’t necessarily that aquatics professionals are lapsing on water quality. Crypto is a game changer because it can do something no other pathogen has managed: resist chlorine, sometimes for more than a week. It’s tough, invisible and tenacious. And one of its favorite hosts is children, a staple at pools and waterparks. Even so, some operators are failing to address issues of hygiene and education, which are essential to reversing the trend. All told, experts say crypto has emerged as a very real public health threat that aquatics professionals must address before it ravages their own facilities.

“Before, it was very easy to follow the paradigm that the pool operator and public health would take care of whatever is in the water,” Hlavsa says. “With crypto, that paradigm no longer applies.”

Understanding crypto

Found everywhere around the globe, crypto is most commonly a drinking water danger, but in countries with advanced water-treatment systems, such as the United States, it’s almost exclusively a recreational water issue. Between 1997 and 2006, crypto comprised nearly 70 percent of all treated water venue recreational water illness outbreaks. E. coli O157:H7, Giardia, Norovirus, Shigella and other agents made up most of the other 30 percent, according to the CDC.

The problem is, while proper chlorine disinfection effectively destroys those other pathogens — it takes less than one minute to eradicate E. coli 0157:H7, and approximately 16 to kill the Hepatitis A virus — crypto is virtually immune. Thanks to a tough-to-penetrate outer shell, it takes more than 10 days to destroy crypto in a normal pool (77 degrees Fahrenheit with free chlorine levels of 1ppm, a pH of 7.5 and no chlorine stabilizers), according to the CDC.

The most common forms of the pathogen are Cryptosporidium C. homius or Cryptosporidium paravum, commonly found in cows. Humans can become infected with either. Both cause severe gastrointestinal symptoms, including diarrhea, stomach cramps, vomiting and nausea, which can lead to fever and dehydration. Symptoms typically last between one and two weeks, but some — those with compromised immune systems, the very old or the very young — may develop more severe or chronic symptoms. In severe cases, the parasite can cause death.

Crypto propagates itself by using its host to spread oocysts (think eggs) that then infect others. These oocysts latch onto cells in the intestinal tract, where the parasite reproduces. It then exits the body through the stool (typically diarrhea), ready to infect another person.

In recreational water,crypto is generally spread via a diarrhea “accident,” which can release many millions of crypto oocysts into a pool system. Because it takes just 10 to 30 occysts to infect a host, simple bad hygiene (not washing hands after changing diapers, for instance), can cause an outbreak.

Innocent as they appear, the youngest swimmers are perhaps the biggest crypto risk. In fact, the Salt Lake Valley Health Department found children under age 5 made up 28 percent of the nearly 700 outbreak-related crypto cases in 2007.

“Kids, who are always touching things and putting their hands in their mouths, are wonderful vectors,” says researcher Joan Shields, a former Centers For Disease Control Foundation Fellow, now at the U.S. Food and Drug Administration.

When crypto strikes, it often affects more than one person, and outbreaks happen when a group of individuals are infected from a common source, such as a pool. Outbreaks occur because once crypto is in the pool, anyone who swallows the water, accidentally or on purpose, may ingest the parasite. Because swimmers often visit multiple pools, they can easily transfer the pathogen across town or into another state. Once that happens, there’s no telling how many people could become infected.

“People who love water love all water, and swim multiple times in multiple venues. So what affects one facility is going to affect another,” notes Julie Marsden, director of the Montgomery County (Pa.) Health Department’s Division of Communicable Disease Control and Prevention.

Two significant outbreaks affected Marsden and her colleagues in 2007, and they found that approximately 12 percent of 213 confirmed crypto victims had swum in multiple public pools.

“That number seems low, but we saw differences in the number of pools people were naming, depending on what point in the outbreak we were looking at. At the start of the outbreak people reported swimming in multiple pools, but toward the end, they reported swimming in just one pool,” says Jennifer Robertson, who worked on the outbreak with Marsden.

Charting crypto’s course

The thousands sickened might not agree, but there’s an upside to the rash of crypto outbreaks in the past several years. It has forced health experts, the aquatics industry and the general public to take notice of the threat.

But that’s taken awhile. Ernest Edward Tyzzer, a distinguished medical parasitologist at Harvard University in Boston first identified crypto more than 100 years ago. However, it wasn’t deemed a serious public health threat until about 35 years ago, when it was first isolated in a human. Many of the first recorded human cases were associated with HIV/AIDS. According to reports, crypto experts Saul Tzipori, Ph.D., and Giovanni Widmer, Ph.D., of the Tufts University Cummings School of Veterinary Medicine, helped clarify its clinical significance in the early 1980s.

Crypto has been around for a long time, but there really wasn’t much attention on the issue before,” says Tom Lachocki, Ph.D., CEO National Swimming Pool Foundation in Colorado Springs, Colo. “The industry recognized that it was a problem … but the fact that there was virtually no data on how to inactivate this pathogen in recreational water conditions until a few years ago — even though it has been making people sick for more than 15 years — reflects poorly on our field.”

The first recorded outbreak of crypto linked to a recreational water setting occurred in Los Angeles in 1988, according to the CDC. But it was a 1993 drinking water outbreak in Milwaukee that really raised red flags and spurred increased funding for research. More than 400,000 persons were affected.

It was a 2005 outbreak in Geneva, N.Y., that put the aquatics industry on notice. Nearly 3,000 people were reported ill, and the spraypark in Seneca Lake State Park was identified as the source.

“From our perspective, the 2005 Seneca Lake outbreak brought it to the forefront.” says Douglas C. Sackett, assistant director, New York State Department of Health, Bureau of Community Environmental Health & Food Protection. Those sickened have filed the industry’s first class action lawsuit, and litigation is currently ongoing.

“When I first started in aquatics 14 years ago it wasn’t a big concern, but as news has come out about the various crypto outbreaks, it’s become more and more of an issue,” says Joe Goss, aquatics supervisor at the Palmdale, Calif., Parks and Recreation Department. “Now we’re very concerned about it.”

Many aquatics professionals concur. According to an Aquatics International survey of approximately 400 readers, nearly 60 percent of respondents answered that they agree (or agree strongly) with the statement, “In the past five years there have been changes at my facility in an effort to prevent crypto.”

Operators say swimmers now are much more knowledgeable as well. In the same survey, nearly 45 percent of respondents say patrons are more aware of crypto than they were five years ago.

Hlavsa says CDC experts have seen an increased awareness in the link between crypto and recreational water. While there’s no definitive evidence, that may be one reason for the increase in reported cases.

Those crypto-savvy swimmers who do get sick may be more apt to seek medical attention and inform physicians of recent pool visits.

And those physicians may be listening. The first drug to treat adults with crypto — Nitazoxanide (brand name Alinia) — was approved in 2005. With a treatment available, health-care providers are perhaps more readily testing patients with gastrointestinal symptoms for crypto, and diagnosing positively.

As a result, it may be that health agencies are receiving more reports on individual crypto cases. Today, they’re much quicker to link positive cases with local swimming pools.

“States are now more likely to be thinking about recreational water when they have a crypto incident,” Hlavsa says. “Before, they might have thought more about food or drinking water.”

Finding the answers

Are more people getting sick, or has greater reporting spurred the recent increase in crypto? Hlavsa and her colleagues can’t say for sure, and without definitive evidence, it might tempting for pool operators to dismiss the problem altogether.

Some are doing just that. Nearly 15 percent of Aquatics International survey respondents say they have no measures in place at their pools specifically to prevent crypto.

“If you haven’t had a crypto outbreak at your pool, you may think you’re doing everything right and it won’t happen to you,” Jensen added.

But experts caution against the blind-eye approach.

“[Even the best] operators need to understand, ‘This could happen to you,’” Bogdanow warns.

Operators of one community swimming facility in Montgomery County, Pa., learned that lesson firsthand. They thought they had a well-maintained pool, complete with UV filtration (which is supposed to kill the pathogen) and other state-of-the-art technologies. Yet, Marsden confirms, it was at the center of the county’s 2007 outbreak.

The lesson? There’s no magic bullet when it comes to eradicating crypto. Even supplemental disinfection systems proven to kill the parasite on contact aren’t a guarantee. That is because a pool’s filtration system can take up to 24 hours to cycle the water through the supplemental sanitation. By then, an outbreak could be well on its way to erupting.

According to Shields, even the cleanest pools can still become contaminated with crypto because ultimately, the spread of the parasite is in the hands of patrons. You can superchlorinate your pool following all recommendations, but as soon as one swimmer with diarrhea enters the water, your pool could be contaminated again.

“We all tried our best to prevent the spread of cryptosporidium, but when push comes to shove, if someone gets in your pool who’s infected, there’s not much you can do,” adds Donna Russell, aquatics supervisor for the city of Clearfield, Utah.

So is being proactive worth the effort? Yes, Jensen says emphatically. A commitment to patron education, proper water chemistry, regular superchlorination and supplemental sanitization technologies (such as ozone or UV) won’t completely eliminate it, but those measures can significantly lessen the chances of a crypto outbreak.

Those who don’t take action risk not only their patrons’ health, but the loss of community support, and potentially catastrophic financial repercussions as well.

“It’s a significant public health risk and although most recover, it can be dangerous,” Bogdanow says. “Operators want people to come to the pool and have a fun, safe experience. But if they don’t take action, the threat will affect people’s [ability to enjoy] the recreation activities offered.”

Jensen saw it happen. When news of the Utah outbreak began making headlines, he noted a significant drop in pool attendance. “We went from jam-packed pools to very empty pools,” he says. “Lifeguards were literally guarding empty pools.”

Elise Knox also saw an immediate drop in attendance when news of an outbreak hit her area last summer. “I saw a drop in enrollment in preschool classes immediately,” the aquatic park manager for the city of The Colony, Texas, recalls. Yet her pool was never linked to a single case.

But just as quickly as they jumped out of the water, people jumped back in, and Jensen and Knox credit proactive, education-heavy approaches to crypto with helping to ease patron concerns and minimize the financial fallout. Showing that you’re doing all you can with supplemental disinfection systems, such as UV, is another way to gain the public’s trust.

For her part, Knox acknowledges that it is challenging to enforce inconvenient policies dealing with personal hygiene — who really wants to tell guests that they need a shower? And, clearly, training a teenage staff to ask grown adults to follow the rules takes time — a precious commodity for most operators, many of whom are wearing multiple hats and facing more immediate issues in other areas of their jobs. But she maintains that anything pool managers can do to prevent crypto will pay off.

Jensen agrees: “It’s an operator’s responsibility to educate the public about crypto. Aquatics professionals educate patrons about the risks of diving, and warn where there’s deep water, and they should take the same approach with crypto.”