Transcript ater Quality, Microbial Contamination, and Health

Water Quality, Microbial
Contamination, and Health
Hazards associated with
Recreational Use of
Freshwaters and Beaches
Colin I. Mayfield
Professor of Biology, University of Waterloo
and Assistant Director, United Nations University International Network for Water, Environment and Health
Recreational waters refer to those natural waters
used not only for primary contact activities, such
as swimming, windsurfing, and waterskiing, but
also for secondary contact activities, such as
boating and fishing.
Recreational use is defined as any activity
involving the intentional immersion (e.g.,
swimming) or incidental immersion (e.g.,
waterskiing) of the body, including the head, in
natural waters.
Natural water is defined as any marine, estuarine
or fresh body of water, as well as any artificially
constructed flow-through impoundment using
untreated natural waters.
Economic Costs
The total global health impact of human infectious diseases
associated with pathogenic micro-organisms from land-based
wastewater pollution of coastal areas has been estimated at
about three million disability-adjusted life years (DALYs) per
year, with an estimated economic loss of around 12 billion
dollars per year (Shuval 2003).
Researchers in the United States have estimated that the health
burden of swimming-related illnesses at two popular beaches in
California, USA exceeds US $3.3 million per year.
The annual costs for each type of swimming-related illness at
the two beaches were estimated to be: gastrointestinal
illnesses, US $1,345,339; acute respiratory disease, US
$951,378; ear complaints, US $767,221; eye complaints, US
$304,335 (Dwight et al. 2005).
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Issues
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Microbial contamination
Sources of contamination
Measurement of contamination
Patterns of contamination of freshwater
Beach contamination
Health Effects
Populations at higher risk
Future risks (emerging pathogens)
Developments in analytical technologies and
control measures
• Summary
Microbial Contamination
The Great Lakes Water Quality Agreement states that:
“recreational waters should be substantially free from bacteria,
fungus and viruses that may produce enteric disorders or ear eye,
nose, throat and skin infections or other human diseases and
disorders”
The primary tool used at present to evaluate water quality is the
measurement of indicator organisms that estimate the level of
faecal contamination of the water
The primary organisms used are faecal coliforms, Escherichia coli
and enterococci.
They are considered indicative of faecal contamination and
possible presence of intestinal-disease-causing organisms
Microbial Contamination
Standards vary, but Ontario closes beaches when E. coli levels
reach 100 organisms per 100 mL
Other jurisdictions use 200 per 100 mL of faecal coliforms as the
criterion.
Is there evidence that increased levels of these indicators leads to
increases in infection?
Risk of contracting Gastroenteritis and Respiratory illness (Acute
Febrile Respiratory Illness) at different Intestinal Enterococci levels
10%
GI
9
8
7
6
5
AFRI
4
3
2
1
0%
0
50 100 150 200 250 300 350
95th percentile of IE/100 mL
European Union Directive 2002/0254
400 450
500
The ratio of Escherichia coli to Enterococci found in those studies
to reflect equal risk was between 2 and 3
The European Union therefore developed the following standards for
“bathing waters”:
Parameter
Excellent Quality
Good Quality
Intestinal enterococci
In cfu/100 mL
100
200
Escherichia coli in
cfu/100 mL
250
500
Monitoring frequency was made flexible to allow for waters with few
contamination occurrences
Potential Pathogens in Fresh water
Campylobacter jejuni — one of the most common causes of bacterial
gastroenteritis and chronic sequelae. The pathogen has been isolated from
recreational waters on many occasions. However, few cases of illness have been
reported through this route. Campylobacter jejuni is more likely to be found in
recreational waters contaminated by animal and human waste.
E. coli O157 — although most outbreaks of E. coli O157 have been
associated with food, a number of outbreaks have been reported from
recreational use of waters, particularly in pools that were not adequately
chlorinated. Haemolytic uraemic syndrome with possible long-term sequelae is
evident although no follow-up studies appear to have been conducted in people
who contracted the infection from recreational water use. The acute disease
tends to be moderately severe and of moderate duration.
Helicobacter pylori — water has been implicated as one mode of
transmission of H. pylori although the detection of the pathogen has proved
difficult. Therefore, it is possible that H. pylori infection is waterbome, but these
assumptions need to be substantiated. Current evidence for its association with
recreational waters is slight.
Legionella spp. — there are a number of reports of Legionnaires’ disease
associated with the use of, and proximity to, hot tubs in particular. The illness is
considered to be severe with a high risk of death and severe acute symptoms.
There are a number of documented cases of persons suffering sequelae as a
consequence of infection with Legionella spp.
Mycobacterium avium complex — there is clear evidence for the
association of Mycobacterium avium complex with recreational waters. The
species of Mycobacterium that are associated with water are associated with a
variety of diseases. Some, such as M. ulverans are pathogenic in previously
healthy individuals, others, such as M. avium, usually cause disease in
compromised individuals. The majority of cases associated with recreational
waters appear to be attributed to swimming pools and hot tubs resulting in skin
and soft tissue infections in immunocompetent patients. However,
hypersensitivity pneumonitis is also seen in immunocompetent persons with
aerosol exposure to mycobacteria.
Salmonella spp.
Shigella spp. — epidemiological evidence exists for the association of
recreational use of water and self-limiting infection with shigella bacteria. The
species responsible for the more severe illness, S. dysenteriae, is more common
in tropical regions but no cases associated with recreational waters were found
in the literature. However, it is biologically plausible that S. dysenteriae could
be encountered in freshwaters used for recreation.
Vibrio vulnificus — this bacteria commonly occurs in marine and
estuarine environments. Evidence exists for the association of recreational use
of water and infection with V. vulnificus where the user has a pre-existing open
wound. Surveillance of V. vulnificus infections is poor and the number of cases
reported is likely to be underestimated.
Cryptosporidium — faecal accidents are implicated in most of the cases as
the cause of the outbreaks of cryptosporidiosis, which have primarily occurred
in swimming pools, although some cases have been documented from water
slides, fountains and water parks. Cryptosporidium oocysts show resistance to
chlorination. The risk of death and probability of developing long-term sequelae
from this infection is low, however the acute illness can be prolonged and
moderately severe especially in immunocompromised persons.
Giardia — recreational use of water is a proven risk factor for giardiasis.
The majority of symptomatic patients of Giardia will clear their infection after
one to several weeks although immunocompromised patients may not recover
from giardiasis. The risk of death and the probability of developing sequelae
from this infection is low, however the acute illness can be prolonged and
moderately severe.
Microsporidia — although microsporidia are currently not common
causes of recreational waterborne disease, their role as emerging pathogens is
being increasingly recognised. Their small size makes them difficult to remove
by conventional water filtration techniques and it is thought that, like
Cryptosporidium they may show increased resistance to chlorine disinfection.
Illness is generally reported in immunocompromised individuals although some
infections in immunocompetent individuals have been reported.
Naegeria fowleri has been shown to colonise warm freshwater habitats,
such as swimming pools and natural hot springs and there is a high risk of death
in infected persons. The acute illness is severe with symptoms lasting more than
seven days and death always occurs. Although the infection is rare, new cases
are reported every year.
Schistosoma spp. — in some cases serious pathology associated with
infection by Schistosoma spp. occurs and can lead to long-term health issues.
Schistosoma is only a potential hazard in certain geographic areas (e.g., subSaharan Africa). Surveillance for schistosomiasis is currently poor, inferring
that many more cases associated with recreational waters occur but are not
published. Evidence shows that exposure to schistosomes is difficult to avoid
but it has been shown that towel-drying after exposure to infested water can
markedly reduce the risk of infection
Adenovirus — the diseases resulting from infection with adenovirus
include conjunctivitis, pharyngitis, pneumonia, acute and chronic appendicitis,
bronchiolitis, acute respiratory disease, and gastroenteritis. Adenovirus
infections are generally mild; however, there are a number of fatal cases of
infection reported in the literature. Transmission of adenovirus in recreational
waters, primarily inadequately chlorinated swimming pools, has been
documented via faecally-contaminated water and through droplets, although no
fatal cases attributable to recreational waters have been documented in the
literature.
Coxsackievirus — although there have been very few outbreaks of
coxsackievirus linked to recreational water recorded, and epidemiological
evidence remains scarce the virus has been frequently isolated from marine and
freshwaters. As with other viruses (hepatitis A virus (HAV), adenovirus and
echovirus) transmission of the virus is possible and biologically plausible in
susceptible persons. Coxsackievirus is responsible for a broad range of illness
from mild febrile illness to myocarditis and other more serious diseases.
Echovirus — as with the other enteroviruses discussed in this review,
there are few published cases of infection by echovirus in recreational water,
those that are recorded are primarily from swimming pool water. The most
likely source of the virus is through faecal contamination, although secretions
from the eyes or throat are possible. There are likely to be many unreported
cases of infection with echovirus.
Hepatitis A virus — has been isolated from surface waters which may be
used for recreational purposes and a number of cases of HAV have been
documented associated with recreational water users. Fulminant hepatitis is rare
and has not been reported in any cases linked with the use of recreational
waters. No cases of sequelae of HAV contracted through the use of recreational
waters were found in the literature and the probability of developing long-term
sequelae is low. The acute disease is usually moderately severe and of moderate
duration but risk of death is low.
Hepatitis E virus (HEV) — has been isolated from surface waters which
may be used for recreational purposes. Fulminant hepatitis is rare. No cases of
sequelae of HEV contracted through the use of recreational waters were found
in the literature and the probability of developing long-term sequelae is low. The
acute disease is usually moderately severe and of moderate duration but risk of
death is low except where cases occur during pregnancy.
Sources of Contamination
Many sources contribute to microbiological contamination,
including:
 combined or sanitary sewer overflows (CSOs and SSOs),
 unsewered residential and commercial areas, and
 failing private, household and commercial septic systems.
Other sources may be:
 agricultural runoff (such as manure
 fecal coliforms from animal/pet fecal waste washed from soil
by heavy rains, either from the beach or washed into
residential storm sewers
 wildlife waste, as from large populations of gulls or geese
fouling the beach
 direct human contact, such as swimmers with illnesses,
cuts or sores; or high numbers of swimmers/bathers in the
water, which are related to increased bacterial levels
 direct discharges, for example from holding tanks of
recreational vessels.
Other factors affecting contamination levels are:
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low (shallow) water levels
hot weather and higher temperatures
high winds that can cause increased wave action that can
transport bacteria from contaminated, non-recreational
areas to recreational-use areas
high winds that can stir up bacteria that are in the
sediments
calmer waters that can slow dispersal and create excess
concentrations of bacteria.
Other Sources
Beach sand and mats of algae floating along shorelines both
harbour E. coli for long periods.
E. coli can even survive over winter in beach sand.
Bacteria sheltered in sand or algae can repopulate shoreline water
with such high concentrations that beaches are closed even when
there are no obvious new sources. Such sources would include
sewer overflows or heavy rains that either flush contaminants out of
storm sewers or wash bird droppings off nearby parking lots.
Whitman (USGS).
Other Sources
As Lake Michigan's water level has receded to near-record low
levels in the last year, beaches have become wider and attracted
more waterfowl, particularly gulls.
Gull feces is loaded with E. coli. "You would need 1,000 geese to match the E.
coli burden from a single gull," (Sandra McLellan, an assistant scientist at the
Great Lakes WATER Institute in Milwaukee)
As beach areas increase, there are higher average concentrations
of E. coli. At one site, North Point Marina, the beach increased in
size by 255% between 1997 and 2000 while average E. coli
concentrations rose 391%.
Mark Pfister, an aquatic biologist with the Lake County Health Department in
Waukegan, Ill consistently found the highest concentrations of E. coli at
Waukegan South Beach where there were no storm or sanitary sewers
discharging close to it, but it did have the greatest number of gulls among
beaches in the county.
Sandra McLellan, an assistant scientist at the Great Lakes WATER Institute in
Milwaukee, agreed that researchers "must cut to the chase" and answer the
question of whether there are pathogens present when E. coli concentrations rise
above federal guidelines for recreational water.
In the meantime, however, McLellan is pursuing one possible surrogate - testing
for caffeine in water. The chemical would come only from sewage, and its
presence would confirm human waste in the water.
McLellan's study of water quality at Milwaukee beaches has found that E. coli
contamination abruptly stops about 10 meters off shore.
"The whole lake is OK," she told those attending Thursday's conference. "We are
seeing local contamination problems at beaches."
Julie Kinzelman, a microbiologist with the City of Racine Health Department, said
that the U.S. Environmental Protection Agency was searching for other indicators
of recreational water quality.
For now, health officials need "to err on the side of caution" and use the E. coli
test, she said.
"We also need to be able to identify whether E. coli is coming from a human or
non-human source," Kinzelman said.
McLellan's laboratory at the University of Wisconsin-Milwaukee should help
municipalities do just that. She is looking for antibiotic resistance in E. coli, a trait
that would only be found in bacteria from humans. In addition, she is identifying
the genetic makeup of E. coli from humans, gulls, cattle and dogs.
Distinct genetic "fingerprints," or sequences of DNA, will help researchers
recognize the source species.
The Risk Management Approach to Ensuring Safe Recreational
Bathing Waters
The most effective way to ensure that our waters remain safe for use is to
become aware of the types of hazards (microbiological, chemical and
physical) that can impact a bathing area. Examples can range from
industrial and sewage discharges, to overland runoff from heavy rainfall, to
safety hazards such as underwater obstructions or currents.
Under the Risk Management approach to safe recreational water quality, a
inspection of the bathing area is first used to identify all of the sources of
risk to human health and safety. Then, appropriate procedures or
management actions are introduced as barriers to reduce these risks.
This concept is similar to the Multiple Barrier Approach used in the
management of safe drinking water supplies. Using this approach,
compliance with the Guidelines becomes but one key piece of a larger
picture of preventative risk management.
For example, if an inspection of the bathing area has determined that the
water quality results are poor following rainstorms, one action might be to
restrict bather access immediately following periods of heavy rainfall.
The majority of beach closings are due to indications of the presence of
high levels of harmful microorganisms found in untreated or partially
treated sewage. Most of this sewage enters the water from combined sewer
overflows, sanitary sewer overflows, and malfunctioning sewage treatment
plants. Untreated storm water runoff from cities and rural areas can be
another significant source of beach water pollution. In some areas, boating
wastes and malfunctioning septic systems can also be important local
sources of beach water pollution.
Combined sewer systems are designed to carry both raw sewage and storm
water runoff to sewage treatment plants. During heavy rainstorms, these
systems can become hydraulically overloaded and discharge a mixture of
raw sewage and polluted runoff from streets into local waterways. The
discharges pollute water around the outfalls and at downstream beaches.
Heavy rainfall can also hydraulically overload separate sanitary sewer
systems which carry raw sewage to sewage treatment plants.
This is especially a problem for systems with excess infiltration of rainfall
through the ground into leaky sanitary sewers and with large inflows from
sources such as roof drains connected directly to sewers.
When flows exceed the capacity of the system, sewers can overflow and
discharge untreated sewage from manholes and bypasses at pump
stations and sewage treatment plants.
The discharges flow into local waterways and pollute the water.
People who swim in water near storm drains can become ill. A recent
Southern California epidemiological study, for example, revealed that
individuals who swim in areas adjacent to flowing storm drains were 50
percent more likely to develop a variety of symptoms than those who
swim further away from the same drain.
Swimmers who did not avoid the drains experienced an increased risk for
a broad range of adverse health effects. These include fever, nausea, and
gastroenteritis; flu-like symptoms -- such as nasal congestion, sore
throat, fever, and/or coughing-- are also possible.
Storm drains can even be a source of problems during drier weather
because broken pipes or connections to sanitary disposal systems may
contribute pathogens to the storm drains
Models for Assessing Potential Water Contamination
Waterborne pathogens reaching recreational areas can originate from
various sources located either within the proximity of the beach or at
upstream locations within the drainage area or watershed. These
sources can be grouped into three categories:
(1) nonpoint source-dominated systems, where pathogen contamination
is governed by rainfall events;
(2) point source-dominated systems, where pathogen impact is due to
either continuous or intermittent discharges; and
(3) episodic releases of untreated wastewater due to uncontrolled
discharges and accidental spills.
Review of Potential Modeling Tools and Approaches to Support the BEACH Program (EPA)
United States Environmental Protection Agency Office of Science and Technology, Standards and Applied
Science Division, 401 M Street, SW Washington, DC 20460
Model Categories
The overall objective of all beach advisory predictive tools is to reduce the risk
of illness due to exposure to elevated levels of pathogens. The tools
currently in use by responsible agencies vary in their complexity and
approach to minimizing exposure.
Rainfall Analysis
In the case of the City of Milwaukee, City of Stamford, and Delaware
Department of Natural Resources and Environmental Control (DNREC), the
approach taken was regression analysis to relate rainfall to pathogen
concentration. Models developed based on this approach are site-specific
since they are derived from locally observed relationships between water
quality and rainfall data.
Simulation of water quality conditions
Models can be used under a variety of scenarios of untreated or partially
treated wastewater. Comparison of the resulting water quality conditions to
the established action level, such as the water quality standard, can serve
as the basis for the beach advisory or closure.
The use of water for recreational purposes poses a number of health risks
which depend on factors such as the nature of the hazard, the
characteristic of the water body and the immune status of the user.
Although evidence from outbreak reports and other epidemiological
evidence have proven a link between adverse health effects and
immersion in poor quality recreational water, the difficulties associated
with attributing an infection to recreational water use are numerous and
the majority of research in this field has focussed on infections associated
with the use of recreational waters resulting in minor, self-limiting
symptoms.
There are many unanswered questions regarding the severity and
frequency of illness associated with recreational water use. It is
plausible that more serious illnesses could result from the
recreational use of water and this association has not yet been
investigated to any great extent.
It is also increasingly apparent that a number of micro-organisms
or their products are directly or indirectly associated with
secondary health outcomes or sequelae and a number of these
sequelae may result from waterborne infections.
• The acute diseases attributable to waterborne pathogens and
their epidemiology have been well described, but the sequelae
that can result from these diseases have not. Assessing
potential sequelae of waterborne infections is a critical part of
microbial risk assessment and the formulation of public policy.
• Even where illness is severe, it may still be difficult to attribute
it to recreational water exposure due to the large number of
other transmission routes of the pathogens in question.
Nevertheless, evidence does exist to show that although much
less frequent, more serious and potentially fatal disease is a
risk to recreational users of water.
Consideration of whether an illness is severe or not is based on
three factors:
• acute symptoms of the disease which are debilitating;
• the ability and probability that the illness will lead to sequelae; and
• the effect of the disease on certain susceptible subpopulations.
Each factor can be considered in its own right or in combination with
one or both of the other factors. A simplified index of severity has
been created and applied wherever possible to the illnesses
considered, taking into account possible sequelae.
The outcome measures used to ascertain the relative severity
are case-fatality rate, average duration of illness, median percentage
of cases requiring hospitalisation, the frequency of development of
sequelae and the severity of sequelae.
The index is limited by the availability of data and does not take into
account the probability of infection following exposure. The index is
designed to help public health professionals prioritize recreational
water management decisions to reduce the potential for severe
disease outcomes.
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Diseases that are normally mild and self-limiting in the general population can
have severe manifestations in susceptible sub-populations with certain
attributes.
A variety of host factors impact susceptibility to severe disease
outcomes. Human immune status can be affected by diseases (HIV, cancer),
age, medications taken (e.g., chemotherapy treatment of cancer weakens the
immune system), pregnancy, nutritional status, genetics and other factors (Carr
and Bartram 2004).
Host factors can influence both the severity of the acute symptoms and the
propensity to develop sequelae (Reynolds 2003).
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The population of immuno-compromised individuals is growing
(Soldatou and Davies 2003). This population is more
susceptible to waterborne infections and tend to experience
more severe outcomes (e.g., debilitating illness, death)
following infection (Reynolds 2003).
• A number of studies have shown that enteric diseases are the
most common and serious problems that affect persons with
acquired immunodeficiency syndrome (AIDS). Between 50%
and 90% of people with HIV/AIDS suffer from chronic diarrhoeal
illness, and the effects can be fatal (Janoff and Smith 1988).
People with reduced immune function due to cancer treatment
have been shown to have a case-fatality rate for adenovirus
infection of 53% (Hierholzer 1992).
Likewise, in the 1993 Cryptosporidium outbreak in Milwaukee,
Wisconsin, USA, 85% of the deaths occurred in people with
HIV/AIDS (Hoxie et al. 1997).
People with liver diseases are at particularly high risk of fatal
septicaemia after ingestion of, or percutaneous exposure to,
Vibrio vulnificus (Levine and Griffin 1993).
Table shows the case-fatality observed for enteric pathogens in nursing
home patients in the USA who are more susceptible to infection compared with
the general population.
There are many unanswered questions regarding the severity and
frequency of illness associated with recreational water use.
The difficulties associated with attributing an infection to
recreational water use are numerous and the majority of research
in this field has focussed on infections associated with the use of
recreational waters resulting in minor, self-limiting symptoms.
However, it is plausible that more serious illnesses could result
from the recreational use of water and this association has not
yet been investigated to any great extent.
It is also increasingly apparent that a number of micro-organisms
or their products are directly or indirectly associated with
secondary health outcomes or sequelae and a number of these
sequelae may result from waterborne infections.
The acute diseases attributable to waterborne pathogens and their
epidemiology have been well described, but the sequelae that
can result from these diseases have not.
Assessing potential sequelae of waterborne infections is a critical
part of microbial risk assessment and the formulation of public
policy.
The guidelines deal with health hazards associated with recreational
water use, as well as aesthetic and nuisance conditions. Health hazards
associated with direct contact with water include infections transmitted
by pathogenic microorganisms, as well as injuries and illness due to
physical and chemical properties of the water.
The guidelines discuss the indicator organisms – enterococci,
Escherichia coli, other fecal coliforms, and coliphages – as well as health
risks related to exposure to waterborne pathogenic bacteria, viruses,
protozoa, and toxic blue-green algae.
Sampling of recreational waters is also addressed.
Other sections deal with physical, chemical, and aesthetic
characteristics, nuisance organisms, microbiological methods of
sampling and analysis, and posting of beaches and other recreational
waters.
Waters used for recreational purposes should be sufficiently free from
microbiological, physical, and chemical hazards to ensure that there is
negligible risk to the health and safety of the user. The determination of
the risk of disease or harm from microbiological, physical, or chemical
hazards is based on a number of factors, including the following:
Environmental health assessments
Epidemiological evidence
Indicator organism limits
Presence of pathogens.
The decision to post a warning to users of recreational areas or to close
an area for public use should be made by the Medical Health Officer or
other appropriate authority in accordance with the statutes existing in
each province.
This decision will be based on an assessment of existing hazards using
available information on the factors listed above.
Environmental Health Assessments
An annual environmental health assessment should be carried out prior to
the bathing season on the watershed or the area from which water flows to
a recreational area, as well as on the recreational area itself.
This survey should identify all potential sources of contamination and
physical hazards that could affect the recreational area.
Attention should be paid to the following:
the risk of inadequately treated sewage, fecal matter, or chemical
substances entering the water, from either a discharge or a spill
knowledge of all outfalls or drainage in the area that may contain
sewage, including urban storm water and agricultural waste or runoff
an inspection of the area for physical hazards
an assessment of the seasonal variability of hazards, the density of
bathers, the water temperature, the frequency of change or circulation
of the water, changes in water depth, and the occurrence of algal
blooms
the fluctuation of water quality with rainfall (wet and dry conditions)
a reporting mechanism to ensure that health authorities are informed
of any malfunction or change to a municipal, private, or industrial waste
treatment facility that might cause a deterioration of the water quality of
Epidemiological Evidence
The local health authorities responsible for making recommendations for
a recreational area should, wherever possible, establish surveillance for
bather illness or injuries.
This can be established by comprehensive epidemiological studies or by
formal and informal reporting from physicians and hospital emergency
departments. This surveillance will be increased if there have been
reports of suspected illness or injuries. The water quality may be
considered impaired and appropriate recommendations made as a result
of this surveillance.
Procedures for the investigation of illness associated with recreational
waters should adhere to the recommendations given in Procedures to
Investigate Waterborne Illness (International Association of Milk, Food
and Environmental Sanitarians, Inc. 1979).
Presence of Pathogens
Tests for pathogenic organisms may be carried out when there have been
reports of illnesses of specific etiology, when there is suspected
illness of undetermined cause, or when levels of an indicator organism
demonstrate a continuous suspected hazard. The tests will help to
determine the source of contamination (e.g., sewage pollution,
agricultural or urban runoff, bather origin).
The local health authorities should take action when pathogenic
organisms are identified in sufficient quantity or frequency to be
considered a hazard.
Such pathogenic organisms may be Aeromonas spp.,
Pseudomonas aeruginosa, Staphylococcus aureus, Shigella
spp., Salmonella spp., Campylobacter spp., Giardia spp.,
human viruses, and toxic phytoplankton.
An appropriate response should be based on the knowledge of
the source of the organism and the probability of the hazard
being temporary or continuous.
The best indicators of the presence of enteric pathogens in fecal
pollution sources should have the following properties (National
Academy of Sciences 1977; Cabelli et al. 1983; Elliot and Colwell
1985):
present in fecal-contaminated waters when enteric pathogens are
present but in greater numbers
incapable of growth in the aquatic environment but capable of
surviving longer than pathogens
equally or more resistant to disinfection than pathogens
easily and accurately enumerated
applicable to all types of natural recreational waters (e.g., fresh,
estuarine, and marine)
absent from non-polluted waters and exclusively associated with
animal and human fecal wastes
density of indicator should be directly correlated with the degree of
fecal contamination
density of indicator should be quantitatively related to swimming
associated illnesses.
Indicator Organism Limits
An indicator organism or organisms should be chosen by the local health
authority in consultation with the laboratory microbiologists for each
area.
It is recommended that one of the following indicator organisms be used
for routine monitoring of recreational water quality – enterococci,
Escherichia coli, or fecal coliforms.
Recreational waters may be contaminated by direct human contact and by
waterborne pollutants from external sources (e.g., sewage, storm water and
agricultural runoff).
Many epidemiological studies have identified gastrointestinal and upper
respiratory illnesses in bathers that were a result of such contamination.
The indicator organisms are surrogates for the presence of pathogenic
organisms that may cause gastrointestinal illnesses.
Escherichia coli, enterococci, and, to a lesser degree, fecal coliforms are
currently considered the best fecal indicators, because they most closely fit
the above characteristics.
Escherichia coli and fecal coliforms
Maximum Limits
The geometric mean of at least 5 samples, taken during a period not to
exceed 30 days, should not exceed 2000 E. coli/L.
Resampling should be performed when any sample exceeds 4000 E. coli/L.
The Working Group agreed that the tests to be used to fulfil these
requirements are as follows:
1. When experience has shown that greater than 90 per cent of the fecal
coliforms are E. coli, either fecal coliform or E. coli may be determined.
2. When less than 90 per cent of the fecal coliforms are E. coli, only E. coli
may be determined.
Summary
1. In fresh waters, E. coli is the best available indicator of fecal contamination
from warm-blooded animals.
2. Klebsiella is not a good indicator of fecal contamination, but it may be
present at high levels in certain industrial wastes (e.g., pulp and paper
mills, food processing plants). It is not likely to cause infection or illness
in healthy individuals.
3. Where there is evidence that greater than 90 per cent of the fecal coliforms
are E. coli, the E. coli and fecal coliform tests will be considered
equivalent.
4. The presence of E. coli is associated with bather-associated illness, but
its absence cannot be equated with the lack of risk of illness.
Summary
5. Current microbiological-epidemiological studies are not sufficiently
validated to allow calculation of risk levels. However, there is some
evidence for increased risk of illness from bathing compared with non-bathing
(i.e., wading or remaining on the beach).
6. The 1983 guidelines were, in principle, based on the definitive fecal
coliform, E. coli. However, at that time, the more general fecal coliform
test was considered the method of choice. The Working Group reaffirms
that E. coli is the indicator of choice and recognizes that either the E. coli
test or the fecal coliform test may be used to enumerate this organism,
depending on the circumstances.
The maximum acceptable concentration of 2000 E. coli (or fecal coliforms)/L
can be calculated to correspond to a seasonal gastrointestinal illness of 1 to 2
per cent, based on the U.S. Environmental Protection Agency studies.
Marine Waters - Summary
1. In marine waters, the enterococci group is the best available indicator of
fecal contamination from warm-blooded animals.
2. Fecal coliforms do not survive well in marine waters and thus may not be
reliable indicators of fecal contamination.
3. Enterococci survive longer than fecal coliforms in marine waters and thus
are preferred when there is considerable time or distance between the
source of fecal pollution and the bathing area.
4. There is a positive correlation between gastrointestinal illness and levels
of enterococci in marine waters, but the absence of enterococci does not
indicate a lack of risk.
5. Based on the U.S. Environmental Protection Agency epidemiological
study, a seasonal geometric mean of 35 enterococci/100 mL corresponds
to a seasonal gastrointestinal illness rate of 1 to 2 per cent. Because fecal
coliforms do not survive well in marine waters, the use of the fresh water
maximum limit may increase the risk of illness.
Coliphages – Summary
1. No limit on coliphages can be established at this time. Monitoring and
epidemiological studies are required to determine the levels of coliphages
in water and the health effects associated with swimming in water
containing coliphages.
Pseudomonas aeruginosa – Summary
1. Pseudomonas aeruginosa is typically isolated from fresh recreational
waters in low numbers. The levels of P. aeruginosa in a bathing area are
influenced by density of bathers, especially individuals that are infected
with P. aeruginosa or are carriers.
2. Levels of P. aeruginosa are influenced by sewage or urban drainage
sources.
3. Pseudomonas aeruginosa has been associated with the occurrence of
otitis externa in bathers.
4. One Ontario study has demonstrated that when levels of P. aeruginosa
exceed 10/100 mL in at least 25 per cent of the seasonal samples, otitis
externa may be expected to occur.
Staphylococcus aureus – Summary
1. Staphylococcus aureus is known to be a major pathogen to man. It is
responsible for boils, ear infections, and other purulent infections.
2. There appears to be a relationship between bather numbers and
staphylococci levels in the water, but there does not appear to be a
significant relationship between bather illness and concentration of
S. aureus in the water.
3. For these reasons, no limit is being established for staphylococci at this
time. Monitoring and epidemiological studies for this pathogen are
recommended.
Salmonella – Summary
1. Salmonella organisms are pathogenic, and a health hazard exists if these
organisms can be consistently isolated from a bathing area.
2. The methods for the isolation of Salmonella have not been standardized,
and routine enumeration is not practical.
3. Salmonella can be considered as a support parameter to aid regulatory
agencies in determining the health risk involved in using waters for
recreation.
Other Pathogens
Shigella
Aeromonas
Campylobacter jejuni
Legionella
Viruses
Summary
1. Viruses are known to be pathogenic in low numbers. As few as one
infective tissue culture unit can cause disease when ingested. Concentration
and enumeration steps are too detailed to make routine monitoring
practical.
2. Very few data are available on current virus levels in recreational waters.
3. There is no correlation between viral and bacterial counts in recreational
waters
Pathogenic Protozoa
Summary
1. Routine monitoring of waters for protozoa is not recommended. However,
provincial laboratories should be able to participate in the investigation of
documented waterborne outbreaks.
Toxic Phytoplankton
Summary
1. No limits are recommended for toxic phytoplankton, but swimming in
waters containing blue-green algal blooms should be avoided.
2. Bather poisonings have occurred after immersion in lakes and ponds
containing dense blooms of blue-green algae.
3. Sampling recreational waters for toxic phytoplankton should be
considered only for epidemiological investigations.
WHO
Beach Pollution
Average E. coli levels from beach sand collected on wet and dry days during
2005 beach season
From: Identification and Quantification of Bacterial Pollution At Milwaukee County Beaches Great Lakes
WATER Institute Technical Report. Sandra L. McLellan , Erika T. Jensen. Great Lakes WATER Institute.University
of Wisconsin-Milwaukee
Larry J. Wymer, Kristen P. Brenner, John W. Martinson, Walter R. Stutts
Stephen A. Schaub*, Alfred P. Dufour. U.S. Environmental Protection Agency Office of
Research and Development, National Exposure Research Laboratory, Cincinnati, OH
45268
EMPACT Study – Highlighted -- Fresh water Beaches
Major findings on spatial variation are:
In every case, the zone from which the sample was collected was
found to have the greatest predictable impact on microbial indicator
densities of all factors investigated in this study, spatial or temporal.
Bacterial densities become progressively lower as one moves from
ankledeep to knee-deep to chest-deep water.
Two of the study beaches, Belle Isle and Miami Beach Park, exhibited
some form of systematic spatial variation that was not adequately
accounted for by zones alone. It may or may not be a coincidence
that both of these beaches are associated with river systems.
Summary of Factors (correlates) of microbial indicators in
recreational waters (from the EMPACT study)
Spatial Factors – lower levels in deeper waters (away from
shore)
Temporal Factors – lower levels in the afternoon than the
morning (often lower on sunny days than on overcast days)
Temporal factors – Faecal indicator levels varied significantly
from day to day – only limited statistical relationship between
sampling on one day and the next day’s samples
Environmental factors –
Substantial rainfall increased levels
Onshore winds increased levels
Bather density did not give consistent effects
Water Recreation and Disease - Plausibility of Associated Infections: Acute
Effects, Sequelae and Mortality Kathy Pond Published on behalf of the World
Health Organization by IWA Publishing, Alliance House, 12 Caxton Street,
London SW1H 0QS, UK
Developments in analytical technologies and control
measures
Current situation is that indicator organisms such as
Escherichia coli only give an indirect estimate of presence
of pathogens
Escherichia coli, faecal coliforms and enterococci survive
for different times in recreational waters based on many
environmental factors such as temperature, aeration,
nutrient availability, etc.
Pathogens may survive for much longer periods and so
absence of indicator organisms may provide a false
negative result
Ideally, all pathogens that can cause disease should be
detected in as short a time as possible to give accurate and
timely evidence for beach closures or warnings to
recreational water users
Pathogen numbers can vary over very short time periods
(hours) in water
Developments in analytical technologies and control
measures
Improvements in detection technologies for pathogens (or even
for more rapid indicator organism detection) would lead to better
and more accurate risk assessments.
Such technologies might include:
Rapid E. coli detection systems based on colour reactions or
fluorogenic substrates coupled with microscopic detection of
colonies on membrane filters
Quantitative Polymerase Chain Reaction (QPCR) to detect and
amplify the DNA of organisms such as enterococci and
Bacteroides species. This test typically takes 2 hours and can
provide rapid, early assessment of contamination
Detection of compounds such as faecal sterols and caffeine
that are thought to be only present in water as a consequence of
faecal contamination – chemical detection methods are routine
and very rapid.
Developments in analytical technologies and control
measures
New technologies based on microchips containing DNA
probes or specific antibodies to pathogens coupled with
detection of changes in physical properties of the
substrates when coupled to the pathogens. Such chips
could, in theory, detect up to 100 pathogens on one chip
and communicate results almost immediately. Work
continues!
Improved descriptions and “libraries” of DNA specific to
human pathogens in water so as to improve the
discrimination of human pathogens from other animal
sources
Improved modelling techniques (maybe on a sitespecific basis) that predict contamination reliably and
accurately based on weather, hydrological conditions,
and contamination events (both non-point source and
point source). These would need extensive calibration
and verification.
Developments in analytical technologies and control
measures
The “ideal” system would:
Detect all pathogens (bacteria, fungi, viruses and protozoa)
that could be present in water in a very short time period
(minutes to hours)
Communicate these results immediately to the responsible
authority
Be reliable (no false negative results), reusable and very
inexpensive
Developments in analytical technologies and control
measures
No such technology exists today, but many laboratories and
companies are working to develop such systems. Such efforts
are usually under the umbrella of “nanotechnology”
But – to quote an old (apocryphal?) Chinese curse: May you get
what you wish for !
What would be the impact (socially, legally, economically, etc) of
having such accurate and immediate information?
Would every beach be closed permanently because of the
detected presence of one pathogenic organism in the samples?
Would the public demand that many, large samples of water or
sand be used to improve detection accuracy?
Monitoring of recreational waters for indicators of fecal contamination has been
required for decades in the implementation of EPA Ambient Water Quality
Criteria (AWQC) to protect swimmers against acute gastrointestinal illness (AGI).
The AWQC criteria were established after epidemiology studies were conducted
in the late 70s and early 80s which demonstrated a correlation of AGI illness
rates to E coli and enterococci levels in the water. While these are good
indicators water quality, they require a 24 hour analysis period after sampling to
find out if the water quality is acceptable for swimming. Recent intensive EPA
monitoring studies have demonstrated that typical water quality may change
rapidly so the water quality often can not be ascertained on the day a person is
swimming
Quantitative Polymerase Chain Reaction (QPCR) technology can circumvent the
problems of having to wait for 24 hours or longer to determine if safe levels of
indicator organisms occur on any given beach day. QPCR provides the capability
to determine water quality within 2 hrs of the start of sample analysis. QPCR
methodology is being studied by the EPA for its use in measuring enterococci in
recreational waters as well as the correlation with levels of AGI from swimming
exposure. Companion studies of this technology are being conducted to
determine if Bacteroides fragilis may also qualify as a recreational water quality
indicator. This fecal bacterium is present in high numbers in the human body and
doesn't grow outside of it.
"We also need to be able to identify
whether E. coli is coming from a human or
non-human source," Kinzelman said.
McLellan's laboratory at the University of
Wisconsin-Milwaukee should help
municipalities do just that. She is looking
for antibiotic resistance in E. coli, a trait
that would only be found in bacteria from
humans. In addition, she is identifying the
genetic makeup of E. coli from humans,
gulls, cattle and dogs.
Distinct genetic "fingerprints," or
sequences of DNA, will help researchers
recognize the source species
Environmental Health Perspectives Volume 114, Number 1, January 2006Rapidly Measured Indicators of Recreational Water Quality Are
Predictive of Swimming-Associated Gastrointestinal Illness
Timothy J. Wade,1 Rebecca L. Calderon,1 Elizabeth Sams,1 Michael Beach,2 Kristen P. Brenner,3 Ann H. Williams,1 and Alfred P.
Dufour31National Health and Environmental Effects Research Laboratory, Human Studies Division, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, USA; 2Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA; 3National
Exposure Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA Full Article in HTMLFull Article in PDFEHP-in-Press
Abstract
Standard methods to measure recreational water quality require at least 24 hr to obtain results, making it impossible to assess the quality of water
within a single day. Methods to measure recreational water quality in ≤ 2 hr have been developed. Application of rapid methods could give
considerably more accurate and timely assessments of recreational water quality. We conducted a prospective study of beachgoers at two Great
Lakes beaches to examine the association between recreational water quality, obtained using rapid methods, and gastrointestinal (GI) illness after
swimming. Beachgoers were asked about swimming and other beach activities and 10-12 days later were asked about the occurrence of GI
symptoms. We tested water samples for Enterococcus and Bacteroides species using the quantitative polymerase chain reaction (PCR) method.
We observed significant trends between increased GI illness and Enterococcus at the Lake Michigan beach and a positive trend for Enterococcus
at the Lake Erie beach. The association remained significant for Enterococcus when the two beaches were combined. We observed a positive
trend for Bacteroides at the Lake Erie beach, but no trend was observed at the Lake Michigan beach. Enterococcus samples collected at 0800 hr
were predictive of GI illness that day. The association between Enterococcus and illness strengthened as time spent swimming in the water
increased. This is the first study to show that water quality measured by rapid methods can predict swimming-associated health effects. Key
words: bathing beaches, cohort studies, diarrhea, gastrointestinal diseases, Great Lakes Region, recreational water, swimming, water quality.
Environ Health Perspect 114:24-28 (2006).