A second lawsuit against Mount Carmel Grove City was filed June 14 by one of the 16 people who had contracted Legionnaires' disease there.

The negligence lawsuit was filed after Mount Carmel stated June 13 the disease outbreak originated in the facility's hot water system and resulted from inadequate disinfection.

Anna Hillis, 59, of Grove City contracted Legionnaires' disease while visiting her brother-in-law at the hospital, according to the lawsuit filed in Franklin County Common Pleas Court. Hillis spent time at the hospital between May 14 and 16, often sitting below the air-conditioning vent in the patient's room, the lawsuit states. Hillis also washed her hands a few times.

Hillis began showing symptoms of the severe form of pneumonia May 25, with a Legionnaires' diagnosis confirmed June 4. She is still using supplemental oxygen therapy, the lawsuit states.

"I was shocked and wasn't sure how serious it was until they started talking about it," Hillis said June 14 at the Brewery District office of her attorney, David Shroyer. Hillis said she started feeling weak, with pain in her abdomen.

There have been at least 16 confirmed cases, but after June 15 the likelihood of new diagnoses will dramatically decrease. Legionnaires' disease has an incubation period of as many as 15 days, and Mount Carmel implemented water-use restrictions May 31.

Mount Carmel is not monitoring any possible cases, which is an indication there might not be any new diagnoses, said Dr. Tammy Lundstrom, chief medical officer for Mount Carmel's Michigan-based parent company, Trinity Health.

High concentrations of Legionella bacteria in the hot-water system explain why those who got sick weren't confined to only one area of the seven-floor hospital.

Any place where someone washed their hands, used the bathroom or showered could have been a source of contracting the disease, Lundstrom said.

Mount Carmel officials said they believe the reason for the outbreak was "inadequate disinfection" prior to the hospital's opening.

The hospital's water system was disinfected in phases, with some portions in February and others in April, when the hospital officially opened. Areas treated in February weren't disinfected again before the new hospital opened April 28.

Tim Keane, a Legionella expert and Mount Carmel consultant, said multiple factors led to the Legionella bacteria growth.

Keane didn't say there were errors in the disinfection process, but he did say sometimes one disinfection isn't enough.

Keane said Mount Carmel is investigating "every area" of the process -- including the length of time between when the system was disinfected and when the hospital opened -- to find the root cause.

He didn't comment on whether errors in construction of the $361 million hospital contributed to the outbreak.

Government regulations don't require hospitals to explicitly test for Legionella, a policy Keane said should be changed.

Temporary water filters are still in use, but those will be removed over time as Mount Carmel has installed a secondary treatment system that constantly adds a dose of disinfectant into the water as its permanent solution.

The disinfectant, called chloramine, is not as potent as chlorine, Keane said, but it's highly effective because it stays in the water system for up to 36 hours.

Of the 16 patients who contracted the disease, one died: 75-year-old Deanna "Dee" Rezes of Grove City. Rezes, 75, died June 2 at the hospital, where she had been admitted May 28 with flu-like symptoms, according to Matthew Wolf, an attorney representing her family.

Mount Carmel is facing at least two lawsuits, and the hospital saw a decline in visits after the week of the outbreak, hospital president Sean McKibben said June 13.

The number is rebounding, he said.