1. Incidence of Cryptosporidiosis due to the presence of
Cryptosporidium spp. in treated recreational
swimming areas in Miami-Dade County, Florida.
Spencer Ash
2015

2. 2
Cryptosporidium and Significance for Public Health:
Cryptosporidiidae are a family of intracellular protozoan parasites that are a significant
cause of gastroenteritis – in particular cryptosporidiosis – around the world.1
The taxonomy of
Cryptosporidium species continues to evolve with the advancement of molecular identification
techniques, although it is known that multiple species can infect humans. The two primary
species that are most often identified as the cause of cryptosporidiosis in humans are C. hominis
which exists through a human-human transmission cycle and C. parvum which is found in
humans and ruminants and exists through unique and intersecting zoonotic transmission cycles.2
Cryptosporidiosis is most commonly transmitted though the fecal-oral route.
Although recognized by veterinarians in the early 1900s, Cryptosporidium spp. were first
recognized as human pathogens in 1976 following the first two reports of cryptosporidiosis in
immunocompromised humans.2,3
Between 1976 and 1982, a total of seven cases of
cryptosporidiosis were reported, mostly occurring in immunocompromised individuals.
However, since 1982, cryptosporidiosis has often been recognized as the cause of severe and life
threatening diarrhea in patients with HIV/AIDS and as a common cause of gastroenteritis in non-
immunocompromised individuals with infection rates of 14-24% and 2.1-6.1% respectively.4,5
The occurrence of cryptosporidiosis can cause significant morbidity and mortality in
humans as a direct result of parasitic gastroenteritis, particularly in immunocompromised
individuals where severe diarrhea is a significant threat. While asymptomatic infections of
Cryptosporidium have been reported, the severity of an infection will vary between individuals
and the integrity of their immune systems. The most frequent symptom in immunocompetent
individuals is frequent, voluminous, and watery diarrhea that is accompanied by abdominal
discomfort, nausea, mild fever, and fatigue.2,3
In these immunologically competent individuals,
cryptosporidiosis is often self-limiting and symptoms will subsided within a period of 1-3 weeks,
with an average duration of 12 days.2
However, after the resolution of symptoms, individuals
may still remain infectious and studies have shown that up to 19% of individuals have stool
samples that test positive for Cryptosporidium for an average of 6.9 days.3
In the at risk
populations such as very young children, the elderly, and the immunocompromised such as
transplant patients, those suffering from viral infections, malnutrition, cancer, or other diseases,
the duration and severity of an infection by Cryptosporidium spp. will depend on the intensity of
the illness and the integrity of the immune system. In these individuals cryptosporidiosis is often
characterized by dehydration caused by frequent bouts of diarrhea, weight loss, abdominal pain,
fatigue, headache, fever, and severe vomiting. For these individuals, cryptosporidiosis can often
become chronic and auto-infectious.2,3
From the 58 cases of cryptosporidiosis reported in 1984,
40 of the patients were reported as being immunocompromised, of which 83% had AIDS and
55% died due to complications related to the infection.4
Other reports have indicated that the
fatality rate for those in the at-risk population is around 61%.3
At the present time, there is no
FDA approved medication regime for cryptosporidiosis and medication trials have been shown
to be inconsistent in treatment or have shown no efficacy – although the incidence of the disease
has been reduced in patients with AIDS since the introduction of antiretroviral therapies.2,3
Occurrence of Cryptosporidiosis:
Between 2009 and 2010, the incidence of cryptosporidiosis in the United States increased
16.9% (from 7,656 to 8,951 reported cases). The rate of reported cases was 2.5 and 2.9 per

3. 3
100,000 population, respectively. Previously, between 1995 and 2004, the annual rate of increase
in the observance of cryptosporidiosis in the US was between 0.4 and 1.3 per 100,000
population.2
These figures are considered to be below the actual presence of infection and the
rate of cryptosporidiosis is suspected to be grossly underestimated due to underreporting, the
occurrence of asymptomatic people who are infected and do not seek medical assistance while
also transmitting the disease, physicians who do not conduct diagnostic work, laboratories that
do not screen samples for cryptosporidiosis, cases that are not forwarded to public health
officials, and the fact that many affected individuals do not seek medical attention since the
symptoms may resolve quickly.2
In 2012, extrapolating from the numbers of reported cases, the
CDC estimated that there are approximately 748,000 cryptosporidiosis cases occurring annually
in the United States with hospitalization costs estimated at $45.8 billion with each ambulatory
care visit related to cryptosporidiosis costing $267-757 depending on healthcare coverage.2
In
Miami-Dade county, between the years 2005 and 2014, there were 349 reported occurrences of
(average of 34.9 per year) of cryptosporidiosis with an average rate of reported cases being 1.4.10
Lifecycle, Dispersal, and Rate of Infectivity:
Like many other waterborne pathogens, Cryptosporidium completes its life cycle within
the gastrointestinal tract of a single host, where as an obligate parasite it reproduces.5,6
The
lifecycle begins with the ingestion of an infectious oocyst by the host and is then completed in
terminal stages within the small intestine (see Appendix I for Cryptosporidium lifecycle).6,7
Towards the end of the cycle, an environmentally resistant oocyst is produced (the only stage
that exists outside of a host) which is then excreted through the host feces where it is
immediately infectious since the oocyst is fully sporulated.5,6,7
In humans, the completion of the
lifecycle for Cryptosporidium spp. has been shown to take as few as 3-5 days and as long as 2
weeks.3
Large volumes of enteric pathogens are able to be excreted in human feces. For
Cryptosporidium, the concentration in stool samples can be between 106
-107
oocysts per gram of
fecal matter.8
The concentrations of excreted oocysts has been reported as being influenced with
age, with younger individuals excreting larger numbers – even if asymptomatic. Infected persons
have been observed to excrete up to 3x109
oocysts per day.8
Cryptosporidium spp. have been
shown to be highly infectious, with human trials (n=29) presenting a median infectious dose
(ID50) ranging from 9 to 1042 oocysts with infections being demonstrated after the ingestion of a
single oocyst.2,3,4,9
In the oocyst stage, sporozoites are protected by an outer wall that will allow the parasite
to remain infective even under harsh environmental conditions such as cold and wet
environments for many months.3
Cryptosporidium oocysts have even been shown to be resistant
to certain levels of UV radiation and are extremely resistant to chlorine disinfection – with the
ability to withstand levels of industrial chlorine disinfection (such as that used in water treatment
facilities) and even to exposure to full strength sodium hypochlorite at 50,000 parts per million.4
Additionally, Cryptosporidium oocysts are 4-6µm in diameter and are able to pass through many
types of mechanical filtration systems, limiting the ability to remove Cryptosporidium from
water supplies in efforts to reduce waterborne transmission of the pathogen.5

4. 4
Since cryptosporidiosis is transmitted through the fecal-oral route and the oocysts have a
large amount of environmental resistance, the excretion of large numbers of oocysts from an
infected individual (human or animal) to a susceptible host can be accomplished through a
variety of ways that include: human-human transmission through direct/indirect contact, animal-
animal transmission, waterborne transmission (water supply or recreational water), foodborne
transmission due to ingestion of contaminated foods, and even airborne transmission if oocysts
are able to lifted into the air (although this has yet to be proven).9
Several studies conducted on
the characterization of risk factors for cryptosporidiosis have shown that overall, the people who
are at greatest risk for infection are those who have contact to 1) recreational water, 2) contact
with live stock, 3) have consumed untreated drinking water, 4) are in close contact with infected
people (ie. daycare workers and family members), and 5) those who have traveled to areas where
the disease is persistent.2
The United States Centers for Disease Control and Prevention have shown that there is a
five-fold increase in the incidence of cryptosporidiosis symptoms during the summer months in
both the US and other countries, suggesting that this trend is consistent with the increased use of
treated recreational water areas during this time.2
In the years 2004-2008, the occurrence of
cryptosporidiosis associated with treated recreation water areas increased 200% (from 3,411 to
10,500 reported cases).11
In 2011, in the State of Florida there were three known recreational
water outbreaks and 33 reported cases of waterborne related illness (see appendix II for a list of
waterborne contributing factors).12
Cryptosporidium has thus become the leading cause of gastroenteritis that has been
reported in association with treated recreational water areas – these include swimming pools,
wading pools, interactive fountains, hot tubs, spas, and waterparks, among others.2,12
With
swimming being the second most popular recreational activity in the Unites States (over 350
million-person events each year) there is a great risk for infection by Cryptosporidium due to the
combination of factors such as: frequent fecal contamination, the large numbers of oocyst
shedding from a single infected person, high bather densities (especially diapered children), the
low median infectious dose, oocyst resistance to environmental conditions (such as chlorination)
and the ability of oocysts to pass through mechanical filtration methods (ie. high rate sand
filtration).2,3,8,13
Fecal accidents in public recreational water areas cannot be avoided – even with
optimal levels of water filtration, disinfection, and quality pool design. Furthermore, the
likelihood of Cryptosporidium transmission increases with the level of use by the public (leading
to greater numbers of infected people, which include diapered children, toddlers, and those who
are incontinent) who shed fecal matter through normal recreational water contact and through
accidental fecal releases at a frequency of approximately 1 accidental release for every 1000
bathers.2,3,8

5. 5
Local Surveillance:
In Miami-Dade County, there are numerous treated recreational swimming areas. For this
report, the focus will be on County run facilities since these facilities provide a representative
sample of other venues due to the sanitation
and safety standards for public pools in
Chapter 64E-9 of the Florida Administrative
Code regulations that apply to all publically
facilities used recreational swimming.
Chapter 64E-9 states that the “regulation of
public swimming pools and bathing places is
considered by the department [of health] as
significant in the prevention of disease,
sanitary nuisances, and accidents by which
the health or safety of an individual(s) may
be threatened or impaired.” At the time of
this observational study, the County was
operating 8 seasonal and 11 year-round
swimming facilities (these exclude the
waterpark, 6 seasonal, and 5 year-round,
facilities which are operated by the City of Miami).
The primary facility observed in this study was the A.D. (Doug) Barnes Park Pool located
within the A.D. Barnes Park at 3401 SW 72 Avenue, Miami, FL. This particular facility was
built in 1975 and has undergone several equipment upgrades in recent years. The observational
component was coordinated through the Miami-Dade County Aquatic Safety Coordinator and
several aquatic managers who provided access to the facility as well as information regarding
established protocols and regulations for water treatment and quality analysis.
The A.D Barnes Park Pool facility sources its water from municipal systems which is
then subjected to numerous cycles of filtration and disinfection throughout the day
(approximately one cycle every six hours). According to the pool management team, all County
facilities aim to meet and exceed the regulations and standards found in Chapter 64E-9 which
call for a circulation turn-over of the full volume of the pool at least four times per day.15
The
recirculating water is sent through a series of three high-rate sand filters which is then disinfected
through the automated injection of sodium hypochlorite (a liquid bleach solution at a range of 1-
10ppm) that is controlled by a computerized system. According to the pool management team,
all operators of this system (which is standard in all but a few facilities which use bromine as a
disinfection method) are required to be certified by the Florida Department of Health under
Chapter 514 of the Florida Statutes which govern the routine surveillance of water quality and
safety at all public swimming pools.
Computer assisted chlorine system

6. 6
From what was visible, the facility had an appropriate pathogen prevention plan that was
established and in place – which included facility engineering and pool design that limited
plumbing crossover between aquatic areas, had multiple levels of filtration and high turn-over
rates that were in accordance with regulations, as well as pool policies that were prominently
posted and required patrons to shower before entering the swimming area. Additionally, there
was easy access to sanitation facilities near the entrance to the pool and from conversations with
the pool management team, the staff was well educated on how to handle a fecal matter incident.
Prevention plans are critical for reducing the occurrence water borne disease transmission and
recreational water inllnesses.13
According to the Aquatic Safety Coordinator there have been no
reported cases of cryptosporidiosis or recreational water outbreaks associated with County run
swimming facilities. While this may be due to the fact that young children ( < age 2) are not
allowed to use the facility, reducing the
possibility of a fecal matter incident and
eliminates the presence of diaper aged
children who are at high risk for
sheading Cryptosporidium oocysts – the
occurrence of Cryptosporidium in the
water is more likely than not highly
underestimated due to the low reporting
of cases and the difficulty of
determining oocyst presence.5
The
County also offers many recreational
aquatic programs for the elderly
throughout the day which may also
increase the risk of both primary and
secondary transmission of
cryptosporidiosis.
The fact that there have been no cases of cryptosporidiosis associated with County run
recreational swimming facilities in Miami-Dade county, does not mean that there has been no
transmission related to those facilities, particularly since recreational swimming areas tend to
amplify small outbreaks when people transport the parasite and other disease from one pool to
another.2
The reduction of the transmission of chlorine resistant infectious parasites in
recreational swimming areas, such as Cryptosporidium, requires a multi-stage approach which
was only partially observed in this study. Under both State and County sanitation regulations the
observed facility was in full compliance, yet effective prevention of the transmission of
Cryptosporidium also requires the enforcement of healthy swimming behaviors (ie. showering
before entry, not swimming if sick, etc.) which is difficult to do successfully and the
implementation of supplemental disinfection and secondary filtration systems.2
While covered in section 64E-9.007 “Recirculation and Treatment System
Requirements,” secondary filtration systems and supplemental disinfection systems are not
required by law. Without methods such as the use of ozone and ultraviolet light as supplemental
disinfectant agents and the use of membrane or diatomaceous earth filtering (high rate sand
filters are unable to capture particles at the size of Cryptosporidium oocysts) it becomes nearly
High Rate sand filters

7. 7
impossible to minimize contamination and control the transmission of the disease if it is not
entirely prevented from entering the pool to begin with.2,3,16
Critique of existing regulations and policies:
The sanitation and safety standards, regulations, and protocols for public recreational
swimming areas (ie. public pools) as established in Chapter 64E-9 of the Florida Administrative
Code and enforced by the Florida Department of Health along with the County Department of
Environmental Health through the issuance of operating permits and inspections are robust and
appear to be quite effective for the control and prevention of the spread of the vast majority of
waterborne pathogens.
However, the unique risks that Cryptosporidium spp. pose to significant populations of at
risk individuals – particularly the immunocompromised – highlights a need for a greater level of
protection than is currently provided by water filtration and disinfection systems that are in place
in public facilities. As highlighted earlier, the use of multiple barriers and levels of refined water
treatment are required to control the spread of Cryptosporidium within a treated recreational
water area. Yet, these systems are often quite expensive and are difficult to justify when there
have been no reported cases of the disease associated with these facilities. Despite this fact, the
public requires protection against the threat of all pathogens that may be injurious to individual
and public health – even more so with pathogens such as Cryptosporidium which are resistant to
current methods of disinfection, difficult to remove from a system, and even more to identify
with the currently available methods.
Furthermore, as our understanding of Cryptosporidium increases, there will be a greater
need to improve upon standards and protocols so that they are able to adapt to and manage the
threat posed by the resulting disease. To do so, there will be a need to coordinate between health
departments (national, state, and local) to ensure cooperation and approval of standards that are
better designed to protect the health, welfare, and safety of the public who are exposed to
pathogenic threats when using public recreational water facilities. To that effect, the CDC has
created the Model Aquatic Health Code (MAHC) which provides voluntary guidance based on
the best available science and practices to help health departments and other authorities improve
the health and safety of recreational water facilities. The MAHC should be utilized by the
agencies in question to coordinate their efforts to improve the design, operation, maintenance,
and policies of treated recreational swimming areas.17

8. 8
Concept Map:
Environmental Policies
Chapter 64E-9 of the Florida
Administrative Code
Recirculation and Treatment
System Requirments for public
facilities
County level health and sanitation
standards
Cryptosporidium
• Low ID50
• Environmentally Resisteant
Ooycst
• Persistent in Environment
• Excreted in high numbers
(106-107 oocysts per gram
of fecal matter)
• Small size (4-6µm)
Unable to be filtered
or disinfected with
conventional systems
Health Effects
• Immunocompetent:
•Diarrhea
•Abdominal discomfort
•Nausea
•Fatigue
•Often self limiting
• Immunocompromized:
•Diarrhea
•Severe Dehydration
•Weighloss
•Abdominal Pain
•Fatigue
•Fever
•Severe Vomiting
•Autoinfectious
•Mortality
Outcomes
• Due to inability to filter
ooycsts and their
environmental stability and
persistence the number of
infections will increase with
pool use.
• Large amounts of
asymtomatic infections
and/or infections that
create mild illness
attributed to other sources.
• Growing percentage of at
risk population with
dibilitating illness, resulting
in severe disiblity and time
in hospital/medical setting.
• Decrease in quality of life
for those who are infected.
• $45.8 Billion in related
healthcare costs (national).
Reccomendations and Preventative Measures
Follow CDC Model Aquatic
Health Code (MAHC)
Install advanced filtration
systems with secondary levels of
disinfection (Ozone and/or UV
light)
Standardize Facility and Pool
design
Increased Coordination and
Communication between
aquatic safety managment team
and healthcare providers /
County health department

9. 9
APPENDIX I: Life Cycle of Cryptosporidium
Figure a: Lifecycle of Cryptosporidium. Source: phsource.us/PH/PARA.Chapter_2.htm
Fully sporulated oocysts, each containing four sporozoites are excreted from an infected
individual in feces. Transmission to a host occurs with contact with or consumption of oocysts,
occurring mainly in contaminated water, exposure to contaminated food sources, or contact with
infected animals or individuals.
Following ingestion and excystation (a), the four sporozoites are released where then then
parasitize the epithelial cells of the small intestine (b, c). The sporozoites then undergo cycles of
asexual (schizogony or merogony) (d,e,f) and then sexual reproduction (g,h) resulting in the
creation of immature oocysts (i) which then sporulate within the host. Two different types of
oocysts are produced –thin walled and thick walled, where the mature thick walled oocysts are
then shed in the host feces (j) and the thin walled oocysts remain in the host in a cycle of
autoinfection (k). The oocysts that are excreted from the host are immediately infective and
environmentally resistant, allowing for further transmission through the fecal-oral route.1,6
.

10. 10
APPENDIX II: List of Waterborne Contributing Factors
This list of waterborne contributing factors of recreational treated venues was compiled directly
from the Florida Department of Health Division of Disease Control and Health Protection12
and
CDC Form 52.12, NORS14
.
1)People 2)Facility Design
 Out of compliance with bather density
requirements
 Primary intended use of water is by
diaper aged children
 Heavy use by child groups
 Fecal/vomitus accidents
 Patrons continued to swim when ill or
within two weeks of being ill
 Operator error
 Intentional contamination
 Combined pool filtration systems
(cross contamination)
 Hygiene facilities inadequate or
distant
 Water demand higher than treatment
system capacity (bypasses systems)
 No supplemental / multiple barrier
filtration (eg. Chlorination, but no UV
or filtration)
 Water temperatures > 86 degrees F
 Cross Connection with wastewater or
non-potable water
3)Maintenance: Equipment and Operation 4)Policy and Management
 Disinfectant control system
inadequate, lacking, or malfunctioning
 Incorrect settings on disinfectant
control system
 pH control system inadequate,
lacking, or malfunctioning
 Incorrect pH settings on control
system
 Filtration system malfunctioning or
inadequate (low flow volume)
 Supplemental disinfection system
malfunctioning, inadequate, or lacking
 Insufficient systems checks (delayed
breakdown detection)
 Lack of preventative maintenance
 Low or no water flow with continuous
feed of chemicals
 Extensive biofilm or slime formation
 Lack of draining or cleaning
 No state/local certified aquatics
operators
 Untrained/Inadequately trained staff
 Unclear communication chain for
reporting of problems
 Inadequate water monitoring
(frequency or test type)
 Employee illness policies not in place
or enforced
 No operator on duty at time of an
incident
 Facility outside of health code /
requirements
 No shock or hypercholorination policy
5)Unknown or Insufficient Information

11. 11
References:
1. Percival, Steven L., et al., eds. Microbiology of waterborne diseases: microbiological
aspects and risks. Academic Press, 2013.
2. Yoder, Jonathan S., et al. "Cryptosporidiosis surveillance—United States, 2009–
2010." MMWR Surveill Summ 61.5 (2012): 1-12.
3. Fayer, Ronald. "Cryptosporidium: a water-borne zoonotic parasite." Veterinary
parasitology 126.1 (2004): 37-56.
4. Guerrant, Richard L. "Cryptosporidiosis: an emerging, highly infectious threat." Emerging
infectious diseases 3.1 (1997): 51.
5. Smith, H. V., and J. B. Rose. "Waterborne cryptosporidiosis." Parasitology Today 6.1
(1990): 8-12.
6. Rose, Joan B. "Occurrence and significance of Cryptosporidium in water." Journal
(American Water Works Association) (1988): 53-58.
7. Korich, D. G., et al. "Effects of ozone, chlorine dioxide, chlorine, and monochloramine on
Cryptosporidium parvum oocyst viability." Applied and environmental microbiology 56.5
(1990): 1423-1428.
8. Gerba, Charles P. "Assessment of enteric pathogen shedding by bathers during recreational
activity and its impact on water quality." Quantitative Microbiology2.1 (2000): 55-68.
9. Fayer, Ronald, Una Morgan, and Steve J. Upton. "Epidemiology of Cryptosporidium:
transmission, detection and identification." International journal for parasitology 30.12
(2000): 1305-1322.
10. "Cryptosporidiosis.." Florida CHARTS Data Viewer: Florida Department of Health,
Division of Public Health Statistics & Performance Management., n.d. Web. 17 Sept. 2015.
11. Hendrix, L., et al. "Violations identified from routine swimming pool inspections-selected
states and counties, United States, 2008." Morbidity and Mortality Weekly Report 59.19
(2010): 582-587.
12. Florida Department of Health Division of Disease Control and Health Protection. “Food
and Waterborne Illness Surveillance and Investigation Annual Report.” 2011.
13. Carpenter, Colleen, et al. "Chlorine disinfection of recreational water for Cryptosporidium
parvum." Emerging infectious diseases 5.4 (1999): 579.
14. CDC 52.12 Form Instructions, National Outbreak Reporting System (NORS).
15. Florida Administrative Code: Rule Chapter: 64E-9, Public Swimming Pools and Bathing
Places.
16. Sorvillo, Frank J., et al. "Swimming-associated cryptosporidiosis." American Journal of
Public Health 82.5 (1992): 742-744.
17. Centers for Disease Control and Prevention: The Model Aquatic Health Code (MAHC): A
Model Public Swimming Pool and Spa Code.