Airborne and waterborne pathogens can be the culprit of many illnesses; some lifethreatening, some not. Those at highest risk are those in an immunocompromised state, but no one is safe from either pathogens effects.

Even with todays standards enforced by the Environmental Protection Agency (EPA), the safety of our drinking water is often found less than ideal. Some estimates project that anywhere from 7 million to nearly 30 million Americans develop a gastrointestinal illness each year from drinking contaminated water.¹ Furthermore, the Centers for Disease Control and Prevention (CDC) estimates that nearly 1,000 deaths occur each year from microbial illnesses stemming from U.S. drinking water.

Waterborne disease results from ingesting fecal-contaminated water. Pathogens can be viruses, bacteria, or protozoa all of which present their own challenges in eradication. For example, Cryptosporidium is present in about 65 to 97 percent of the surface water in the United States.¹ The following is an excerpt addressing this topic:

Neither chlorine disinfectant nor standard water filtration systems fully remove this pathogen (Cryptosporidium) from drinking water. Moreover, pathogenic protozoa parasites are the problem microbial, the contaminant that poses the greatest risk to human health. Unlike bacteria and viruses, protozoa parasites are resistant to commonly used treatment procedures. During their life cycles, some species persist in an environmentally resistant cyst stage. They are considered to be about 10,000 to 50,000 times more resistant to disinfectant than are bacteria. Even water treatment by filtration may not do the job, since parasites such as Cryptosporidium are small enough to pass through filtration systems. Protozoa parasites are sometimes called the super bug.

So, in an otherwise healthy environment, the chances of contracting a waterborne-related illness are already higher than some may be comfortable with. Now, add to that a major disruption localized or environmental and the odds increase exponentially.

In the healthcare setting, infection control practitioners (ICPs) are familiar with Legionnaires disease. Outages disrupting the water supply can disrupt the biofilm in the pipes which can release not only gram-negative organisms, but could also release legionella and other potentially infectious waterborne pathogens.

Add to the mix outages associated with electricity which can affect critical ventilation systems. Unscheduled outages do occur, and in such a crisis as a hurricane, one can count on numerous, widespread outages to emerge. However, much to the surprise and delight of Louisiana state officials and ICPs, not much in the way of transmissible disease relating to waterborne or airborne pathogens has transpired as a result.

There really havent been any exposures to anything out of the ordinary. Nothing, states Deoine Reed, PhD, infection control manager and epidemiologist with the Tulane University Hospital system and the Ochsner Clinic Foundation. It is kind of disappointing because we were hoping to see something, but nature has it so it actually can protect the people somehow. Its positive, good news. Nobodys getting infected.

Have any airborne or waterborne pathogen transmission been reported in Louisiana since the hurricane? Yeah, but nothing different from the usual, says La. State epidemiologist Raoult Ratard, MD, MPH. Ratard says Louisiana experienced the usual flu season and upper respiratory diseases, but, It does not look like it was more than usual, he says.

Investigators reported an increase in Vibrio infections in the first eight days immediately following Katrina 14 cases were reported then two later cases erupted. Since, Ratard says the number of Vibrio cases are in line with the usual annual reported rates. We always have about 10 a year, he explains. This year, we are between 10 and 15 for the year. So nothing really different.

He continues, Now what was different is the number of rumors. There was a bunch of rumors of this or that, so whenever we hear the rumor that there is this disease or this one, we try to go find out. None of them turned out to be true.

Reed says that it is interesting to note that the incidence of Clostridium difficile has decreased since the hurricane. We had some issues pre-storm, and it seems to have gone away since actually. Not such a big deal since the storm, she says. Reed adds that the reason for the decrease is a bit of a mystery. We dont know (why there has been a reduction). There is no correlation. Nothing really has changed so we dont know really what that is all about.

Even with the outages that occurred throughout the state, Reed adds that she hasnt seen any incidence of Legionnaires Disease either. Her hospital system, she notes, never had a disturbance in its water supply. Everything checked out. We did not have to turn off our water supply. We were functioning at full capacity the whole time. We were successful, she boasts.

Outside of Reeds hospital system, however, according to surveillance reports reported by the state of Louisiana Department of Health and Hospitals, from January through August 2006, 10 cases of legionellosis were recorded. This number appears much higher than from years past. In fact, in 2003, 2004, and 2005 the number of cases of legionellosis ranged only from zero to five.

Mold was indeed expected to become the biggest problem for the state to face. With so much flooding and it already being such a humid climate, the outlook appeared bleak, at best.

There is a lot of mold growing, acknowledges Ratard. Many houses have been remediated, but there are still a lot of houses that have not been even started.

Ratard says invasive disease is the biggest concern as a side effect of the mold, but he points out this would only be prevalent in those who are immunocompromised.

In immunocompromised individuals, the incidence of invasive infection can be as high as 50 percent and the mortality rate often rests around 50 percent as well.² Reed says the CDC is conducting an ongoing study and enhanced surveillance to include every type of fungus within the area and is looking at invasive mold disease in the immunocompromised patient population.

Ratard says the lack of invasive disease reported in the area among this patient group may be surprising but he explains that those in an immunocompromised state are simply steering clear of the mold-laden areas. It looks like most of these patients really have not returned to their homes to fix their homes themselves. Either they stay away or they hire somebody to fix the house. He adds that the area hospitals have not seen an increase in invasive mold disease either.

But can distancing themselves really be enough? Just to offer an example of how mold spores can be spread and how unsuspecting individuals can still be at risk, in 2002, Johns Hopkins researchers conducted a study assessing the ability of hospital air handling systems to filter Aspergillus as well as other fungi and particles following the implosion of an adjacent building.³ The scientists found that Aspergillus counts rose more than tenfold at outdoor locations up to 200 meters from the implosion site. In addition, total fungal counts rose more than six-fold at 100 and 200 meters and two-fold at 400 meters. Similar to Aspergillus, particle counts rose several-fold following the implosion at 100 and 200 meters.

A similar study was conducted measuring the load of filamentous fungi in the air following the demolition of a maternity building at a Madrid hospital. 4 Samples were collected before and following the demolition, and were obtained from external air, non-protected internal air, and from protected internal air. A significant increase in the colony count of filamentous fungi occurred after the demolition, with counts returning to baseline levels after day 11. A significant increase in the fungal colony counts also was found in external and non-protected internal air.

Another issue that arises from the mold, according to Ratard, are allergies or allergic reactions. They immediately are going to begin to have a serious reaction and they are going to get out, he says, adding that those prone to allergic reactions will immediately begin to break out in hives or the mold will exasperate their asthma. He says that the most common emergency department presentation since Katrina has been asthma exasperation from the mold. Still the incidence is slight; however, it is interesting to note that the interaction of Aspergillus fumigatus and other airborne fungi with the immune system is increasingly linked to severe asthma and sinusitis.² The third thing that molds will do is if you stay within a moldy environment for a long time, it is going to smell and its going to be unpleasant. Peoples eyes will be watery, their nose will leak, and then after a while you will get out and breathe some fresh air. It does not last very long.

These people are not going to go to their doctor or present to the emergency department. They are going to go buy an over the counter medicine and then go back and continue their clean up. So there is a lot of mild irritation, but nothing that looks very serious that we can pick up from our surveillance system.

There were all kinds of Dooms Day predictions about mold invading the city and attacking people, but it does not seem to have happened, he asserts. Educating the residents helped in the reduction of the spread of disease. Ratard says there was a lot of training going on, but the CDC then did a survey and found that many who were cleaning their own homes, were not using the personal protective equipment (PPE) properly.

Reed and Ochsners infection control department partnered with CDC, National Institutes of Occupational Safety and Health (NIOSH) and the United States Department of Agriculture (USDA) to further educate and arm the citizens of the area.

Residents were informed by CDC/NIOSH industrial hygienist, Lynda Ewers, PhD, of several post-hurricane infection control safety precautions. During the seminar, emphasis was placed on wearing PPE such as the N-95 mask. Information sheets, and post-hurricane infection control kits which included two 3M Healthcare N-95 masks, Tegaderm transparent dressing, nail cleaners, and Avaguard alcohol hand sanitizer, were distributed.

We gave the full bang, Reed recalls. We utilized the local media to let them know they should use the PPE when cleaning up their homes. On TV, youll see many wearing their masks they may not be the N-95 mask all the time, but with some sort of protection. That helped.

According to the surveillance data distributed by the state of Louisiana Department of Health and Hospitals on Katrina Cough, which is a dry, continuous cough some Louisiana residents report having, nothing truly significant has occurred relating to upper respiratory disease or invasive infections due to mold spores. The researchers conclude that while the mold, debris, and other airborne contaminants following the hurricane have irritated many, in most cases the irritation has not been significant enough to require an emergency department consultation.

Reed says Ochsner did increase its surveillance at its door for coughs and other presentations of airborne pathogen transmission, but nothing significant ever arose. There wasnt anything out of the ordinary, she shares. There have been some reports of increased asthma exasperations, but nothing that I have actually looked into or studied myself.

In addition to the aforementioned numbers of legionellosis, data shows that the comparison for January through August 2005, and January through August 2006 show Vibrio cases to have halved. Moreover, it is interesting to note that across the spectrum the number of infectious diseases reported in 2006 compared to 2005 is significantly lower in number.

They are reporting numbers, warns Reed. If they were rates, maybe we could look at something. The population is just not as full here as it was pre-Katrina. We really dont know (why there is a dramatic dip in the numbers). It could be real, but I doubt it. I dont think it is underreporting, but its the report we have as such with the population base which has definitely decreased.

Reed guesses that less than half the population now resides in the afflicted areas. I dont put much credence in those numbers, she concludes.


1. Gelt, J. Microbes Increasingly Viewed as Water Quality Threat: The Emerging Contaminants.

Arroyo. March 1998, Vol. 10 No. 2. accessed online Feb. 20, 2007. arroyo/102micro.html.

2. Nierman WC. Genomic sequence of the pathogenic and allergenic filamentous fungus Aspergillus fumigatus. Nature. 2005 Dec 22;438(7071):1151-6.

3. Srinivasan A, et al. The ability of hospital ventilation systems to filter Aspergillus and other fungi following a building implosion. Infect Control Hosp Epidemiol. 2002 Sep;23(9):520-4.

4. Bouza E, et al. Demolition of a hospital building by controlled explosion: the impact on filamentous fungal load in internal and external air. Hosp Infect. 2002 Dec;52(4):234-42.

Industry Offers Solutions to Fight Airborne Pathogens

There are number of solutions in the marketplace that can provide weapons against airborne pathogens. Germicidal ultraviolet light (UV) is one such tool and a mainstream technology that is enjoying increasing popularity as an indoor environment improvement solution, according to American Air & Water, Inc. For example, the U.S. General Services Administration Office of the Chief Architect has incorporated UV in the facilities standards for public buildings and indicates that ultraviolet light can help control airborne and surface microbial growth and its transfer. Essentially, UV radiation breaks down the genetic material in viruses, bacteria, mold, fungi, and spores by smashing their DNA. Ultraviolet rays have shorter wavelengths than visible light; ultraviolet wavelengths range from about 1nm to 400nm and are beyond the range of visible light. Ultraviolet rays with wavelengths shorter than 300nm are extremely effective in killing microorganisms. The most effective sterilizing range for UV is within the C bandwidth called germicidal bandwidth.

Germicidal UV technology has been used for decades to disinfect air and surfaces and to sterilize liquids. UVC technology is designed to produce sterile surfaces, air, and liquids that are 99 percent free of all microbial contaminants. UVC technology can be utilized to inhibit microbial growth and transfer in hospitals through HVAC and stand-alone fixtures via : UVC for coil irradiation (installation of UVC fixtures for direct irradiation of the cooling coils); UVC air disinfection (installation of in-duct UVC air cleaners for air stream irradiation and indirect UVC fixtures for upper air irradiation); direct UVC fixtures for open surface sterilization; and UVC sterilization for operating rooms (a combination of air and surface sterilization).

When it comes to personal protection against airborne pathogens for healthcare workers, several options exist related to powered air purifying respirators (PAPRs). PAPRs reduce decontamination time, and increase online work time, and provide flexibility and increased freedom of movement by the wearer. Bio-Medical Devices International Inc. offers a positive-pressure, hose-free respiratory protection system to be used against aerosolized pathogens for up to 12 hours of operational time. It features a quiet motor mounted inside the helmet, which circulates air over the face, eliminating fogging and increasing worker comfort. Also offering PAPRs for the healthcare environment is Bullard, whose respirators are designed to offer significantly increased protection (over N95 masks) against SARS, tuberculosis, avian influenza, and other airborne pathogens. The Bullard PAPR is also designed to provide an alternative to inconvenient fit-testing.

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