Pathogen control

Michael Beach of the CDC examines the various faces of waterborne pathogens and the need for stricter regulation and greater awareness.

“Good hygiene, good health practices and understanding that chlorine doesn't kill everything instantly is paramount”
-Michael Beach

In light of the current H1N1 pandemic and the ever-increasing public concern over HAIs, waterborne pathogens was traditionally an area often overlooked, surprisingly more so in Western societies than would be expected. Michael Beach, a CDC specialist in waterborne pathogens, defines the illnesses as "those that are spread by having contact with, ingesting, breathing aerosols from substances contaminated by water from either a chlorinated type of aquatic venue, freshwater lakes and rivers, or the oceans."

The most common recreational water illness pathogen that is reported to the CDC is Cryptosporidium in its various species - it is currently the major cause of diarrheal illness related to recreational water - and is reported to be an even larger player in treated aquatic illnesses. "It's a chlorine-resistant parasite and so it bypasses the major barrier that's in effect in our home and public pools because it's resistant to chlorine," explains Beach.

Recreational illnesses

The number of outbreaks in disinfected venues in the US, caused by Cryptosporidium, has risen by 70 percent in recent years. As a developed country operating a vast number of swimming pools, the US sees a minimum of 360 million visits to recreational waters a year in the US. Beach adds that the statistic of recorded visits is much lower than the number of actual visits.

"Cryptosporidium is chlorine resistant," he explains. "We're advocating for the expansion of the paradigm of pool water treatment. For decades we've relied solely on filtration and chlorination, now we need to move towards supplementary disinfection as well. UV light and ozone can inactivate the Cryptosporidium quite well, and so we'd like to see those added routinely as part of swimming pool construction.

"A bank of UV lights that go in usually after the filter system that irradiate the water going through it, and so it's a flow-dependent technology - you've got to pass all the water out in the pool back through this, and so it's not an instantaneous disinfection system as chlorination, instantaneous meaning that there's chlorine throughout the entire water. With UV you do have to rely on how long it takes to circulate all that water back through the system, which is why it can only be a supplementary disinfection system because it doesn't leave a residual in the water that would keep on disinfecting."

Beach explains that the data for knowing how many pools are currently operating this system across the US is poor. However, the CDC is able to judge the incorporation of this via the sales of the units. There has been a recent surge in the sale of units and the number of them being installed, although the exact number, again, is vague. The CDC is advocating the installation of these units to be compulsory and built into pool codes. He notes the progression of New York State - following the outbreak at Sprayground, a recreational area, this has now been written into their regulations for splash parks. 

Currently in the US there are no federal regulations; swimming pools are regulated at the state or local government level, and that is where the CDC is aiming to begin driving its enforcement protocols. Waterborne diseases, after a long period of being overlooked, are beginning to receive recognition, from both the state and America's public. Beach notes that despite seeing cuts in many areas of healthcare, waterborne pathogens has not suffered. "People are starting to recognize that this is a poorly understood, under-recognized area that is actually probably bigger than we think it is, at least in the United States," says Beach

"Regulation at the state and local level means you can walk from one state to another and see dramatic differences in how pools are maintained and operated under a pool code. The CDC being a non-regulatory function, we're trying to develop a national consortium and a model code at the national level with local and state partners. It doesn't have regulatory authority because there is no such authority, but it's a model that's data-based, knowledge-driven and can change over time with new data that becomes available.

"That will then allow state and local health departments to look at that, pull what they want and then put that into pool code, rather than the current system of every group sitting down and reinventing the wheel every time. We'd like to see that a code is data-driven. Some things may make good sense, but over time we'd also like to have the data behind them. If there's a model there that's renewed and updated on a regular basis with new data-based recommendations, that's what the state and local health departments need so that they don't have to go in and redo this themselves alone. They can become part of a national consortium to do that."

Hospital-based infections

Recreational pools are the not the only arena in which waterborne pathogens are present. Beach argues that again, this is an area in which better documentation is needed. The state is heavily focusing on reducing the number of hospital-acquired infections, but water can impact a hospital setting in a variety of ways: this may be through direct contact, or via hydrotherapy tanks in pools that can spread many of the same diseases that are present in a recreational water setting. Also, if drinking water is contaminated, ingestion can produce disease.

It is essential for medical equipment to be cleaned and sterilized but waterborne diseases may threaten this in the form of biofilms. Beach explains that biofilms are a complex microbial population that lives in the slime layer on surfaces with water running over them. Biofilms are likely to harbor many organisms, including pathogens, which they tend to protect from disinfection, and so currently there is much analysis being done to understand more as to what a biofilm community is. "If you put your hand inside just about anything where you've got water, the scum on your teeth, the dog's dish, when there's that scum inside, all of that's a biofilm which is a microbial community, and so that's an area which is being explored more," explains Beach. 

"Clearly, what we see are inhalation of aerosols from showerheads and cooling towers and other sorts of things that can contain pathogens such as Legionella or Mycobacterium avium complex. Dialysis machines and biofilms can be impacted by water quality and contamination. The major issue is that a hospital essentially houses a very sentinel population that is more likely to have severe illness and more prone to becoming infected when they become infected with some of these pathogens, so you tend to pick it up more readily in such a setting.

"They could be wound infections, GI illnesses, respiratory infections and so on, so we routinely document Legionnaire's disease outbreaks in healthcare facilities. Part of that is due to vulnerable populations of elderly and weakened immune system - the sorts of individuals where you're likely to have a severe pneumonia, which has a mortality rate associated with it as well. These are currently really big issues in the US: how do you control biofilms and Legionella levels that can be spread through an entire building or hospital via water distribution system. You can cover the gamut of disease from respiratory, contact, GI illness, wounds and so on, depending on how that potentially contaminated water is entering the body.

"It's a whole universe of exposures that can potentially occur, as they do in many other places. Premise plumbing is certainly an issue from the water-borne disease standpoint, and that could be the plumbing inside a hospital just as well as it can be the plumbing within a building."

Awareness

Awareness of hygiene and infection control is increasing, from drinking water facilities to hospitals to recreational water facilities. There is still huge room for improvement, explains Beach; especially in educating the American public that waterborne does not necessarily mean just drinking water. Over the past five years, the CDC has been collecting more data, trying to improve surveillance and tracking outbreaks. Although drinking water outbreaks have declined over the decades within the US, recreational water outbreaks have been doing the reverse.

"In the developed world we don't see typhoid and cholera anymore, many of those diseases have disappeared, what we see now are pathogens that are exploiting manmade habitats, like Mycobacterium and Legionella. We see chemicals in other personal care products, in water, disinfection byproducts, breakdowns in premise plumbing and other systems that lead to outbreaks. It's a different model of waterborne disease - it's not that it's gone, it's just taken on a different face. We have to educate all risk reduction specialists in the complexity of different things that occur here, and so we tend to do a lot of focus out at the local level on food-borne disease.

"We need to integrate waterborne disease prevention into their thinking at the same time because many of these same pathogens are transmitted by both food and water and we want people to understand that it's not just about enteric GI illness here. It's about respiratory pathogens, neurologic pathogens, wound infections, respiratory and so on. In a recreational setting we need to think about the human body, that you're putting this human body with many openings into a potentially contaminated water allowing pathogens to enter from any orifice, and so let's think about how we protect people and protect the water. Clearly much of this is also about behavioral issues: we are not practicing good common sense hygiene practices when we go to the pool."

Beach compares our recreational water habits to the Europen term bathing, believing this to be a view that Americans should learn to adopt. He adds that showering is often done when people get out of the pool, not before, which is vital for practicing good hygenie. He also notes the necessity in not taking a child sick with diarrhea to the pool, which although sounds like common sense, the amount of parents that do this is the cause of the outbreaks continuously seen when analyzing contaminated water.

"Good hygiene, good health practices and understanding that chlorine doesn't kill everything instantly is paramount to us combating this," he says. "It has to be multi-factorial, we cannot do this without the public becoming more aware and starting to change practices. Part of this is about operation, as well as behavior. We also want to see consumers demanding good operation of public pools, there is no reason that you walk up to a pool and it's not operated properly," concludes Beach.

Waterborne pathogens are as much the responsibility of local health departments as they are that of the American public. As Beach notes, there is still a long way to go in improving the rate of infections, but until they become a thing of the past the CDC continues to raise awareness.

Michael Beach is a specialist at the CDC in recreational waterborne illnesses.

Sprayground shut down

The New York State Health Department shut down Sprayground, a recreational water area, on August 15, 2005 following information that the water holding tanks, which were used to recycle water, were contaminated with Cryptosporidium. 415 cases were confirmed to be the effect of the pathogen, with 33 of those being hospitalized. The plaintiffs alleged the State of New York was negligent and therefore responsible for the illnesses.