E&A News Page 5

Preventing E.coli Transmission Through Swimming Pool WaterAlison Osinski, Ph.D.

The recent occurance of E.coli atWhite Water Atlanta sparked na-tional concern about transmissionof E.coli through swimming pool wa-ter. Due to the many phone callsshe received seeking information,Dr. Osinski prepared the followingpaper on E.coli, and gave us per-mission to use it in this issue of theE&A News. Ed.

Escherichia coli (commonly referredto as E.coli) are a form of coliformbacteria. (See insert) Some strainsof E.coli can cause severe, lifethreatening symptoms. E.coli canbe transmitted from an infected indi-vidual through introduction of fecalmatter into pool water. Because oftheir mobility, the constant circula-tion of pool water, and aerosoliza-tion of organisms from splashing bypatrons, and agitation of water fromhydrotherapy jets, sprays, foun-tains, geysers and other water fea-tures, E.coli can move easily andrapidly throughout the pool or water-park area.

Fecal contamination of pool watercan result from any of the followingsources:• Human fecal matter intention-

ally or accidently being de-posited in the pool,

• Animal,rodent & bird droppings• Fecal matter tracked into the

pool area on shoes,• Fertilizers or grass blown into

the pool from adjoining land-scaping,

• Contaminated ground water,reservoirs or wells,

• Rain and storm water run-offinto the pool

• Illegal cross connections be-tween the pool circulation andsewage systems.

Fecal contamination of pool water

can cause serious illnesses. Inges-tion of contaminated water whileswimming, inhalation of water va-por above the pool surface andbody contact with pathogenic or-ganisms, absorption through bodyorifices or open wounds whileswimming can result in transmis-sion of a variety of diseases. Somepathogens may cause mild gas-trointestinal discomfort. E.colicauses gastroenteritis with symp-toms of diarrhea, cramping, nauseaand vomiting. Some strains ofE.coli, such as 0157:H7, responsi-ble for the June outbreak at At-lanta's White Water waterpark, andthe Jack-in-the-Box tainted ham-burger outbreak a few years ago,result in life-threatening symptoms.Bacterial infections may, or maynot, be successfully treated withantibiotics.

If fecal matter is introduced intopool water, it can be neutralizedthrough proper sanitation and oxi-dation. However, sanitizer efficacydepends on several factors, includ-ing:• Residual disinfectant levels

maintained in the water• oxidation reduction potential• 24-hour uniform circulation pat-

terns and absence of deadspots

• Physical characteristics of thewater such as IDS level andamount of suspended colloidalsolids present

• whether settled materials arebeing removed through vacu-uming

• the percentage of water circu-lating through the perimeteroverflow system

• frequency of dilution and drain-ing of the pool

• filter media effectiveness• pH levels & water temperature• bather load to water volume

The length of bather exposure tothe pathogenic organism, whetherpathogens are imbedded in higherorganisms such as algae, the den-sity or number of organisms pre-sent in a specific volume of water,and the microbe strength or viru-lence will also determine the likeli-hood of disease transmission.

To lessen the probability of fecal

Pathogenic, or disease causing, or-ganisms include bacteria, viruses,protozoa and fungi. Bacteria aresingle-celled micro organismswhich do not contain chlorophyll,divide by simple division, and canonly be seen with a microscope.(They are typically 0.5-1.0 micronsin size.) Some bacteria cause dis-ease in humans , (pathogens),while others have beneficial pur-poses (for example: fermentation,removal of harmful gasses from theair, or decay of dead organic mat-ter). Bacteria occur in three forms:spherical (cocci), rod shaped(bacilli), and spiral (spirilla).

Bacteria are further classified as:aerobic (oxygen breathing) vs.anaerobic (CO2 breathing); motilevs. nonmotile (whether they canmove or not); sporulating vs. non-sporulating (whether they formspores); and gram negative, grampositive, or acid fast - which relatesto results of chemical staining testsused to distinguish cell wall thick-ness, chemistry and permeability ofbacterial cells.

Coliform bacteria belong to Enter-obacteriacae, a family of aerobicand anaerobic, gram- negative, rodshaped, non-spore forming, highmotile bacteria that are found in theintestines of warm-blooded ani-mals, including humans.

Page6 E&A NewsE.coli cont

contamination, ask swimmers touse the toilet before entering thepool and to wash their hands withsoap and hot water, or preferablytake a hot, soapy shower in thenude, prior to entering the pool orre-entering the pool after using thetoilet. Do not permit diaper chang-ing at poolside. Request that pa-trons not use the pool if they aresuffering from an illness that causesdiarrhea or have had diarrhea in thepast two weeks. Require the wear-ing of "swimsuit diapers" or tightfitting rubber/plastic pants by chil-dren who are not yet toilet trained.Request that patrons remove theirstreet shoes when walking on thepool deck.

In addition, do not allow pets toswim in the pool, and try to preventwild animals, birds and ducks fromusing the pool as a watering hole.Good pool and deck design will pre-vent grey water, waste water orsewage from draining or backing upinto your pool.

If a fecal accident does occur:• Have swimmers exit the pool

and close the pool for 24 hoursor a minimum of 3-4 completeturnovers.

• Remove as much of the solidfecal matter from the pool aspossible

• Dispose of the fecal matter to asanitary sewer

• Disinfect the skimmer net, leafrake or vacuum equipment usedto remove the fecal matter

• Raise the free chlorine residualto at least 20ppm, and monitorand maintain the 20ppm FACresidual for a minimum of 9hours in order to achieve aneffective CT value

• Keep the pH between 7.2 and7.4 to increase the percentageof hypochlorous acid formation

• Backwash the filters and disin-fect filter media or elements witha solution of 20 parts of water to

1 part of 10-15 sodium hypochlorite(liquid pool chlorine) prior to re-opening the pool.

In small wading pools and spas, itmay be more effective to follow theabove listed recommendations, butat the end of the fourth superchlori-nated, 30 minute to 1-hour turnoverperiod, drain the pool. The poolshell and filters should be scrubbedwith a sodium hypochlorite disin-fectant solution (20 parts of water to1 part of 10-15% sodium hypochlo-rite), prior to reassembling the filtersand refilling the pool with water.

Perform bacteriological analysis onwater samples taken from the poolwhether your state or local healthcodes require that tests be per-formed by an independent labora-tory on a regular weekly or monthlybasis or not. Simple tests are nowavailable for on-deck testing by pooloperators. If a pool operator onlytests for chemical levels in the wa-ter, and does not monitor bacterialgrowth, he/she will probably be un-aware of a bacterial contaminationproblem until bathers start com-plaining of infection.

Follow the manufacturer's or lab'sdirections to avoid contaminatingsamples during the collection pro-cedure. Use a neutralizing buffersolution (often sodium thiosulfate orquaternary ammonia compounds)to inhibit residual sanitizers thatmight be in the sample. Do nottouch parts of collection devicesthat come into contact with the sam-ple. Collect water samples from 12-18 inches below the water surfaceto obtain a representative sample.Disperse the sample onto thetreated growth medium. For sur-face monitoring, swab the surfaceto collect microorganisms. Placethe sample in an environment favor-able to microorganism cultivation.Incubate (usually at room or speci-fied warm temperature) for 24 hoursfor bacterial tests. Try to preventthe formation of condensation

inside samples since the liquid con-densate will drop into the sampleand disperse the microorganism.

Examine the results without openingthe sample after the culture hasbeen incubated. Count the coloniesto determine the concentration ofmicrobial contamination. Or, deter-mine the presence or absence of theparticular microorganism in the sam-ple. If using the membrane filtrationtechnique for testing total coliforms,fewer than one colony per 100millileters should develop.Presence-absence tests should indi-cate absence of the organism. If themultiple tube fermentation method isused, none of the five standard tenmilliliter portions should show thepresence of organisms of the col-iform group at any time. Coliformpresence in test samples indicatesfecal contamination of the pool. Iftotal coliforms are present in thesample, then testingfor E.coli shouldalso be performed.

Just a reminder — handle carefullywhen disposing of bacterial cultures.Do not open the vials or petri dishesbefore sterilization in a microwaveoven (not used for cooking food), inan autoclave, by sterilization inbleach, or by approved disposal asa bio waste. And, do not allow swim-mers back in the pool until testsshow the water is not contaminated.

In addition to the preventative mea-sures suggested in the above arti-cle, we would suggest signage indressing rooms to reinforce the useof soap showers, and continued ef-forts at public education through thenews media and educational hand-out literature.The knowledgeable people atWhiteWater Atlanta acted/reactedrapidly, or that occurance couldhave been much worse. We mustall make an effort at public educa-tion on this and similar problems.Ed.