Diarrhea outbreak linked to parasite found in pools is spreading throughout southern US state

An outbreak of diarrhea-causing parasitic illness linked to swimming pools is sweeping across Northern Kentucky.

The Northern Kentucky Health Department has confirmed about a dozen cases of cryptosporidiosis in the region, and many of the peopled confirmed to be sick had visited pools in their area.

The parasite that causes crypto, Cryptosporidium hominins, is highly resistant to chlorine, the quintessential ingredient in keeping pools clean. Normal concentrations of the chemical in swimming pools do not destroy it.

The outbreak’s point of origin is still unknown, but a family recreation center with pools and waterslides called Silverlake in Erlanger, Kentucky, had to close down in order to boost chlorine levels and kill any remains of the parasite.

Silverlake, a family pool and fitness club in Erlanger, Kentucky reopened recently after having to ramp up chlorination in its pools to kill off the crypto parasite making people sick

A person infected with the parasite passes infectious spores in their feces.  

Another becomes sick when they accidentally touch or swallow infected fecal matter.

When ingested, these spores migrate to the small intestine and invade intestinal cells to produce more spores. 

As the parasitic cells grow, they inflict damage on the wall of the intestine, which leads to watery diarrhea, abdominal pain, nausea, and a low-grade fever.

The infection is usually self-limiting, meaning it resolves on its own without medical treatment. Infection typically lasts about two weeks. 

Unless a person has particularly weak defenses, the body’s immune system attacks the parasite and limits its ability to reproduce in the GI tract.

For this reason, children and seniors, who tend to have weaker immune systems, are at particularly high risk of a severe bout of illness lasting several weeks.

Steve Divine, Director of Environmental Health and Safety at the Northern Kentucky Health Department, said pools must ‘super chlorinate’ to kill off the offending parasite: ‘Raise the chlorine level up much higher than you normally would for everyday operation.

‘That has to go for a certain number of hours and then let it come back down for a normal range again before people can swim again.’

Silverlake did just that when the health department learned about half the cases of crypto could be traced back there. 

The club released a statement assuring the public that the pool had been ‘super chlorinated to ensure the levels were well beyond what is necessary to kill crypto.

‘Once this process was complete and chlorine levels returned to safe levels, we were cleared by the Health Department to reopen the pool. This process took over 42 hours to complete.'

The origin of the outbreak remains unknown, though about half of the people who became sick were said to have visited Silverlake. Health Department officials expect the current crypto case count to rise

While summer fun was able to start back up at Silverlake, Mr Divine remains convinced that the outbreak will not stop there: ‘We have at least 12 cases that have been tested and confirmed. That number is going to go up.’

The infection can spread quickly in the pool, regardless of how diligent officials are about monitoring chlorine levels. 

Standard pool chlorine levels of one to three parts per million are not sufficient to kill off the pathogen, which can survive there for about a week, depending on water temperature.

An infected person can shed millions of crypto spores in their stool. A tiny amount entering the pool can cause widespread illness.

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Super-chlorinating the parasite to death involves raising the chlorine level to about 20 parts per million and maintaining that level for around 13 hours.

Aside from swimming pools, childcare centers are contamination hotbeds, accounting for 13 percent of outbreaks.

Mr Divine said: ‘I'm not just concerned about pools at this point, I'm worried about daycares. And now that schools are back in session, those as well.’

The CDC recommends that anyone using the pool rinse off under the shower before and after going in, take any children at the pool to the bathroom regularly and make sure they wash their hands thoroughly, keep a child from swimming if they’ve recently had diarrhea, and never change a baby’s diaper poolside; always in the restroom.

Dr Joseph Eisenberg, chair of epidemiology at the University of Michigan School of Public Health, said: ‘Not swallowing water is difficult when a child is active in the water and continually submersing their head. 

'A parent can be proactive by making sure the swimming facility is doing a good job in managing risks at the pool.'

And if you become infected, remember to stay hydrated, Dr Eisenberg said.

‘Especially if it's a child experiencing having diarrhea. The loss of fluids can result in more serious illness, and getting fluids through an IV is something we can all try to avoid.’