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Introduction:
Cryptosporidium parvum, a protozoan parasite, is found in the
feces of infected people, cattle, and other domestic animals.
It has been a recognized human pathogen since 1976. It affects
people with HIV infection and other immunosuppressed persons
more severely than the general population. It has been identified
as a cause of sporadic human gastrointestinal disease and sometimes
of outbreaks - the largest being the 1993 waterborne outbreak
in Milwaukee in which more than 400,000 persons became ill.
It has also been transmitted by person-to-person contact in
child care setting, through food, and through sexual activity
that involve contact with feces.
Cryptosporidiosis has become a significant public health issue,
particularly because studies indicate that Cryptosporidium oocysts
are present in 65%-97% of surface water prior to treatment (i.e.,
rivers, lakes, and streams) tested throughout the U.S. Because
Cryptosporidium is highly resistant to chemical disinfectants
used to treat drinking water, physical removal of the parasite
from water by filtration is an important component of the municipal
water treatment process.
Conventional water filtration should trap nearly all protozoan
parasites, including Giardia and Cryptosporidium, if the water
is properly processed with adequate equipment and optimal procedures
(coagulation-flocculation) are conducted by well-trained operators.
However, a small number of Cryptosporidium oocysts may occasionally
get through the treatment process to the finished drinking water.
Reports of Cryptosporidium oocysts in treated municipal water
that was meeting U.S. Environmental Protection Agency (EPA)
turbidity standards indicate small numbers of oocysts breached
water treatment filters in 27%-54% of the communities evaluated
. The health risk associated with drinking filtered tap water
contaminated with small numbers of C. parvum oocysts is unknown.
More general information on the organism, transmission, and
prevention are found in Attachment 1.
The EPA has promulgated a plan to collect data concerning the
occurrence of several pathogens and chemicals in water and the
ability of water treatment plants to remove these substances.
The plan, known as the Information Collection Rule (ICR), was
published in the May 14, 1996 Federal Register. This Rule applies
to large water systems serving at least 100,000 people and using
surface water or groundwater influenced by surface water (these
systems will test for certain microbial and chemical parameters),
and groundwater systems which serve at least 50,000 people (these
systems will only test for chemical parameters).
A total of three water systems in Maryland is impacted by ICR
requirements. One system is using groundwater and is required
to monitor for disinfection byproducts. The other two are surface
water systems and are required to monitor for both microbial
and chemical parameters.
The microbial testing requirements include monitoring source
water for Cryptosporidium, Giardia, viruses, total coliforms,
and fecal coliforms. If levels of Cryptosporidium or Giardia
in source water exceed 10 organisms per liter of water, or if
one or more total culturable viruses in one liter of water are
recovered, then the treated water leaving the plant must also
be monitored for these organisms.
ICR monitoring began in July 1997, and will continue for 18
months. Utilities will report data to EPA on a monthly basis
and will have four months from the time of sampling to conduct
the analyses and submit the data. EPA will then validate the
data and make these results available to the public. More information
on the ICR can be found in Attachments 2A, 2B and 2C.
In September 1994, the Centers for Disease Control and Prevention
(CDC) National Center for Infectious Diseases convened a workshop
entitled "Prevention and Control of Waterborne Cryptosporidiosis:
An Emerging Public Health Threat." The purpose of the workshop
was to discuss ways to minimize the public health risks associated
with waterborne cryptosporidiosis by addressing four key issues:
-
surveillance and epidemiological study designs
-
public health responses when oocysts are detected
in drinking water
-
cryptosporidiosis in immunocompromised persons;
and
-
water sampling methods, interpretation of
data, and laboratory research priorities.
Two major publications have followed that workshop: "Assessing
the Public Health Threat Associated with Waterborne Cryptosporidiosis:
Report of a Workshop" and "Cryptosporidium and Water: A Public
Health Handbook". At the state level, prior to promulgation
of the ICR, a Cryptosporidiosis Task Force was formed in February
1995 and the following Cryptosporidiosis Action Plan for Maryland
was formulated in order to protect the health of Maryland citizens.
At the state level, prior to promulgation of the ICR, a Cryptosporidiosis
Task Force was formed in February 1995 and the following Cryptosporidiosis
Action Plan for Maryland was formulated in order to protect
the health of Maryland citizens.
Maryland Cryptosporidiosis
Task Force:
The Maryland Cryptosporidiosis Task Force convenes
to define and monitor the progress of the Cryptosporidiosis Action
Plan and to review new information regarding cryptosporidiosis
and public health protection. Members include representatives
from the Maryland Department of Health and Mental Hygiene (DHMH)
Office of Office of Epidemiology and Disease Control Programs (EDCP) and the AIDS Administration,
Maryland Department of the Environment (MDE), Health Education
Resources Organization (HERO), the Chesapeake Section of the American
Water Works Association (AWWA), and public and private surface
water utility companies in Maryland
Goals of the Cryptosporidiosis
Action Plan for Maryland:
- to prevent waterborne cryptosporidiosis;
- to educate water service company employees, health departments,
health care providers, the public, and the immunosuppressed
population about cryptosporidiosis; and
- to outline situations where "boil water" orders should
be issued and conditions under which such an order should
be rescinded.
Plan of Action in Maryland
I. Prevention:
Protecting Public Drinking Water Attachment 5 provides
some general information on public drinking water supplies in
Maryland.
A. Ground Water Protection
Wellhead Protection concepts form the basis of various
preventive approaches to maximize the safety of public water wells
in Maryland. Regulatory standards begin with statewide application
of well construction to ensure the integrity of the supply (Code
of Maryland Regulations [COMAR] 26.04.04). An important preventive
measure includes determining if a well is under direct influence
(UDI) of surface water (COMAR 26.04.01).
The UDI wells are identified using geological review
and application of various techniques such as dye studies, and
using a special sampling protocol. Then, corrective measures such
as remediation of sink holes and filtration of groundwater are
applied to ensure that the water supplied is free from microbial
contamination.
B. Surface Water Protection
Studies have shown that Cryptosporidium is common
in surface waters throughout the United States. As a result, occasional
presence of oocysts in Maryland's surface water should be expected.
Various preventive approaches have been used in Maryland to maximize
the safety of drinking water and to prevent cryptosporidiosis.
The first preventive approach is pollution prevention
at the source. In Maryland, there are major pollution prevention
activities at the watershed level. These activities are a combination
of various program efforts such as Maryland Agricultural Cost
Share (MACS) funding, National Pollutant Elimination Discharge
System (NPDES) program, and the Maryland Tributary Strategies.
While the focus of these efforts is to reduce the load of nutrients
entering the Chesapeake Bay, they also reduce the load of pathogenic
microorganisms going into rivers in Maryland.
In addition, as a result of the Safe Drinking Water
Amendment passed in August 1996, MDE's Public Drinking Water Program
has initiated a new coordinating effort, through technical and
financial assistance, to maximize watershed protection practices
of each surface water supplier. MDE's Public Drinking Water Program
is also beginning a study on the variability of Cryptosporidium
in drinking water intakes on the Potomac River. The study will
also collect data on Cryptosporidium levels in wastewater discharges
and the significance of their contribution to levels measured
at intakes.
Another preventive approach is targeted toward
water treatment plants to ensure that reliable and effective treatment
in the plant can be maintained continuously. This approach involves
performance evaluation of water treatment plants through
- routine sanitary inspections;
- design review of the water treatment facilities prior to
construction;
- technical assistance to the plant's staff;
- review of various compliance monitoring, particularly microbial
monitoring and monthly operating reports of the plants as
required by the Surface Water Treatment Rule (SWTR); and
- operator training and certification program.
In addition to the above, Comprehensive Performance
Evaluations (CPEs), are conducted by MDE to evaluate filtration
plants' performance and determine factors that limit performance.
CPEs and follow up improvements are important tools for optimizing
plant performance. Maryland is one of a few states that conducts
CPEs for its surface water treatment plants. Attachment 6 shows
Maryland surface water treatment plant intake locations.
C. Distribution System Protection
To prevent post-treatment contamination of water,
the integrity of the distribution system must be maintained continuously.
Various preventive measures such as routine maintenance, repair
of distribution system components, and cross connection control
programs should be used to achieve this goal.
D. Routine Testing of Water
Maryland regulations require the routine testing
of public water systems for many parameters, including turbidity
and coliform bacteria (COMAR 26.04.1). Turbidity, which is measured
many times a day in surface water treatment plants, is a measure
of particulate matter in water and is an indicator of the effectiveness
of water treatment processes that remove pathogens such as Cryptosporidium.
Coliform bacteria are indicator organisms; their presence in water
indicates the possibility of contamination with pathogens. The
presence of coliform bacteria could be a result of problems with
ineffective water treatment or lack of integrity of the distribution
system
Under the ICR, two surface water systems in Maryland
are required to test for several microbial contaminants including
Cryptosporidium. Currently, there is no other regulatory requirement
for routine Cryptosporidium testing of water systems in Maryland.
II.
Public Health Response
and Risk Communication
To educate public health officials, water utility
officials, health-care providers, immunosuppressed populations,
and the general public about Cryptosporidium and drinking water,
various activities have been conducted in Maryland.
Click
here to view pages that summarize these activities.
III. Routine Surveillance and Epidemiological
Methods
The CDC work group suggested seven approaches to surveillance,
the following four of which are relevant to Maryland:
- make cryptosporidiosis a reportable condition and monitor
laboratory data for Cryptosporidium;
- monitor sales of antidiarrheal medications;
- monitor the incidence of diarrhea in nursing homes; and
- make immediate epidemiological assistance available when
necessary.
A. Make cryptosporidiosis a reportable condition
in Maryland, monitor laboratory data, and monitor cryptosporidiosis
among AIDS cases.
Effective October 1, 1996, Cryptosporidium was added
to the list of agents reportable by laboratories in Maryland under
Health-General Section 18-205, Code Annotated. EDCP will coordinate
with the surveillance program of the AIDS Administration to obtain
ongoing data on numbers of cases of cryptosporidiosis among AIDS
patients reported. Increases will be evaluated to determine possible
sources.
B. Establish pilot surveillance for sales of
anti-diarrheal medication.
Since early 1995, Maryland has conducted surveillance
for the sale of anti-diarrheal medications in cooperation with
one large pharmacy chain. Total unit sales of three popular anti-diarrheal
products by store location are reported weekly to EDCP. By monitoring
sales of antidiarrheal products, we hope to determine the baseline
normal volume of sales in a non-outbreak situation, and recognize
any increases in sales which may be the result of a cryptosporidiosis
outbreak. Significant increases in total unit sales compared to
baseline, could result in various action steps including:
- Surveys of affected communities to determine prevalence
of gastroenteritis, symptoms, duration, and diagnosis;
- Active surveillance for gastroenteritis cases in affected
communities through emergency rooms, hospitals, nursing homes,
and physician offices; and
- Heightened surveillance for Cryptosporidium infection through
emergency room testing of patients with diarrhea for Cryptosporidium.
C. Monitor the incidence of diarrhea in nursing
homes.
At this time, outbreaks are reportable (COMAR 10.06.01)
in Maryland including diarrhea outbreaks from long term care facilities.
Long term care facilities are aware of the reporting requirements
and each year EDCP receives approximately 30 to 60 reports of
diarrhea outbreaks in these facilities.
The Outbreak Division of EDCP will maintain surveillance
for diarrhea outbreaks and will maintain a high index of suspicion
for outbreaks of diarrhea where the agent is not known, and the
duration of illness exceeds that expected for viral gastroenteritis.
The Outbreak Division will report cryptosporidiosis cases or outbreaks
in long term care facilities to the LHD (if not previously known
to the LHD), and to the MDE. Cases will be investigated (See Attachment
9A and 9B). MDE will coordinate actions with the local water utility.
Pilot projects may be considered in nursing homes
with good data collection or in communities where water quality
may be questioned to establish ongoing diarrhea surveillance and
to determine causative agents.
D. Make immediate epidemiological assistance
available.
The Outbreak Division of EDCP will work closely
with MDE, DHMH AIDS Administration, and DHMH Licensing and Certification
Program when any situation is identified where there may be questions
of water quality or reports of gastroenteritis confirmed or suspected
to be cryptosporidiosis.
IV. Prevention in Immunocompromised
Individuals
Recommendations: On June 16, 1995 the EPA
and the CDC released a joint statement concerning recommendations
for people with severely weakened immune systems (Attachment 4).
The Maryland Cryptosporidiosis Task Force accepts these recommendations.
The following summarizes that statement:
- Current EPA drinking water safety standards were not explicitly
designed to assure the removal or killing of Cryptosporidium.
While the magnitude of risk for acquiring cryptosporidiosis
by drinking municipally treated water in the non-outbreak
setting is presently unknown, the risk is not zero.
- Because people with severely weakened immune systems are
likely to have more severe and more persistent symptoms from
Cryptosporidium infection than healthy individuals, immunocompromised
individuals may want to take extra measures to avoid waterborne
cryptosporidiosis. These extra precautions include boiling
drinking water for one minute, using certain drinking water
filters, or using certain bottled waters.
- Boiling water is the most effective approach for killing
Cryptosporidium.
- Only point-of-use filters that remove particles one micrometer
or less in diameter should be considered. Even with that,
individuals should follow the manufacturer's instructions
for filter use and regular replacement to assure Cryptosporidium
removal (see Attachment 3).
- Many, but not all, brands of bottled water may provide
a reasonable alternative to boiling tap water. Individuals
should carefully read the label and not presume that all bottled
waters are absolutely free of Cryptosporidium. Any bottled
water treated by distillation or reverse osmosis before bottling
assures Cryptosporidium removal (see Attachment 3).
V. Emergency Response: Guidance for Testing
Water and for Issuing and Rescinding Boil Water Orders when Waterborne
Pathogens are Suspected
- Emergency response may be necessary in one of two situations:
- when problems of increased gastroenteritis known or suspected
of being waterborne are reported to the MDE, the LHD or DHMH;
or when water quality is known or suspected to present a risk
to public health.
This guidance is intended for use by Maryland drinking
water program staff and water utilities in making critical decisions
about the use of boil water orders (BWO) for protecting the public
from waterborne pathogens.
Decisions about BWOs must frequently be made within
short time periods and with incomplete or inconclusive information.
Professional judgment by knowledgeable regulatory, water utility,
and public health officials is required. Both MDE and DHMH have
emergency coverage and can be reached at the following telephone
numbers:
- MDE: 410-243-8700, 410-631-3937, or 410-631-4409
- DHMH: 410-795-2100 (A state emergency operator at Springfield
Hospital Center)
- 410-678-8143 (DHMH Duty Officer)
A. Testing Water in Emergency Situations
Environmental Article section 9-406 of
the Annotated Code of Maryland gives the Secretary, MDE broad-ranging
powers to take any necessary action, including testing of water,
to ensure a safe drinking water under emergency circumstances.
Laboratories capable of Cryptosporidium analysis
are listed in Attachment 7. Under the ICR all samples for Cryptosporidium
and Giardia must be analyzed by laboratories that meet stringent
EPA criteria established for ICR purposes. EPA is occasionally
revising the list of these approved laboratories, the most updated
of which can be obtained through the Safe Drinking Water Hotline
at (800) 426-4791. Water sampling techniques are provided in Attachment
8. More information on various testing methods for Cryptosporidium
can be found in "Cryptosporidium and Water: A Public Health Handbook"
B. Issuing Boil Water Orders (BWO)
When making a decision on whether to issue a Boil
Water Order (BWO): 1. Water utility and regulatory officials should
determine whether any of the following circumstances exist:
a. An acute violation of total coliform rule (TCR) or a violation
of the SWTR (surface water treatment rule) turbidity standard;
b. A non acute violation of the TCR (e.g., main
break, cross connection);
c. Positive test results for pathogens in finished
water (e.g., Cryptosporidium, Giardia, Salmonella, or Shigella)*;
d. Failure of or significant interruption in key
water treatment process(es)/ monitoring (e.g., turbidity spikes
of increases particle counts, mechanical or equipment failure,
or persistent monitoring deficiencies); or
e. Evidence of a disease outbreak of gastroenteritis
where drinking water has been implicated as a potential source
of the organism.
f. A natural disaster that may adversely affect
water quality (e.g., flood, hurricane, earthquake). *
When evaluating positive test results for pathogens, consider:
- the approval status and experience of the laboratory
with environmental samples,
- the appropriateness of sample collection and test methods
for water,
- the inherent limitations in the test methods.
- For Cryptosporidium, negative results do not necessarily
indicate the absence of organisms and positive results do
not necessarily provide an accurate assessment of the number
of organisms present, nor of their infectivity or viability.
- The time between collection of the sample and the availability
of results. For example, a BWO may not necessarily be advisable
if a positive test result was associated with a sample that
was collected a month ago versus a few days ago.
2. Water utility and regulatory officials should
determine whether any of the following challenges to source water
quality, treatment effectiveness, or distribution system integrity
exist:
a. Source Water Quality
The vulnerability of the source to contamination.
Source waters should be considered vulnerable if they have access
to cattle or dairy operations, sewage or sanitary discharges,
or heavy recreational use.
- The results of previous monitoring for pathogens
in source water. Source waters should be considered
less vulnerable if adequate routine monitoring for pathogens
or their indicators (fecal coliforms) have shown consistently
negative results.
- The potential changes that affect source water quality.
Source water quality will be adversely affected by sewage
or manure spills, runoff events, turn over events, destratification
of a reservoir, or other circumstances that cause a
deterioration in raw water quality such as recent heavy
or persistent rainfall, floods, or wind.
b. Treatment effectiveness
- Plant optimization for pathogen removal. An optimized
plant is capable of producing a high quality finished
water on a continuous basis regardless of changes in
raw water conditions. Such a plant would be unlikely
to pass significant numbers of pathogens into the water
distribution system. An optimized plant should have
implemented an ongoing plan for treatment optimization
such as offered by EPA or the AWWA.
- Treatment upset or interruption. Whether considered
to be optimized or not, failure or interruption of key
treatment processes can occur. Coagulation, flocculation,
sedimentation, filtration, disinfection or other individual
water treatment processes are all critical to remove
pathogens. Mechanical difficulties or operational deficiencies
can cause plant upsets.
- Finished water quality. Turbidity levels and changes,
particle counts, and disinfection levels and residuals
should be evaluated.
c. Distribution system integrity
The following should be evaluated:
- presence of pathogens or indicator organisms;
- disruption to the distribution system such as low pressure,
- main breaks, or cross connections;
- recent construction that might interrupt water flow;
- stagnant water;
- disinfection residual;
- adequacy of the flushing program;
- a poor recent sanitary survey;
- age of the system.
C. Rescinding a BWO Officials should rescind
a BWO when the following criteria are met: Source water quality
has improved: criteria include turbidity levels, fecal coliform
counts, cessation of storm events.
- Treatment is effective and treatment deficiency(ies) has(have)
been corrected.
- Finished water quality has improved: Total coliform, fecal
coliform, and E. coli counts are negative; turbidity is low
with no spikes; successive pathogen monitoring tests show
results below level of concern; sufficient finished water
displacement has occurred in the distribution system to eliminate
water that was or might have been contaminated. If the BWO
was issued because of detection of a pathogen, then the analytical
method(s) and its inadequacies must be considered when rescinding
a BWO.
- Evidence that the incidence of disease has returned to
normal. Due to long incubation periods and secondary spread
of some pathogens, new cases may continue to occur after the
period of contamination has ceased.
References
- Rose JB. Occurrence and significance of Cryptosporidium in
water. Journal of the American Water Works Association 1988;80:53-8.
- Rose JB, Gerba CP, Jakubowski W. Survey of potable water
supplies for Cryptosporidium and Giardia. Environmental Science
and Technology 1991;25:1393-400.
- LeChevallier MW, Norton WD, Lee RG. Occurrence of Giardia
and Cryptosporidium spp. in surface water supplies. Appl Environ
Microbiol 1991;57:2610-6.
- LeChevallier MW, Norton WD, Lee RG. Giardia and Cryptosporidium
spp. in filtered drinking water supplies. Appl Environ Microbiol
1991;57:2617-21.
- LeChevallier MW, Moser RH. Giardia and Cryptosporidium in
raw and finished water. Journal of the American Water Works
Association 1995;87:54-68.
- Centers for Disease Control and Prevention. Assessing the
public health threat associated with waterborne cryptosporidiosis:
report of a workshop. MMWR 1995;44(No. RR-6).
- Centers for Disease Control and Prevention. Assessing the
public health threat associated with waterborne cryptosporidiosis:
report of a workshop. MMWR 1995;44(No.RR-6).
- Cryptosporidium and Water: A Public Health Handbook. Atlanta,
Georgia: Working group on Waterborne Cryptosporidiosis. 1997
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