E. Coli and Disease Transmission

Escherichia coli (E. coli) is a gram-negative bacteria that can cause severe symptoms such as abdominal cramps, diarrhea, and dehydration. This article discusses the different strains of E. coli, their transmission, and the global distribution of outbreaks.

BIOL 4P85
Exam 2 (Part one)
Mohammed Ibrahim
5939608
1. Answer to question 1A
Woodland Caribou are currently listed under the Species at Risk Act (SRA) as an
endangered species. Such a listing implies that the population of herds are quickly dwindling at
alarming rates and that if nothing gets done the species might soon be extinct. Environmental and
Natural Resources (ENR) gave a disturbing report that the population of the Bathurst herd

declined from 20,000 to 8,000 between 2015 and 2018 (Panza-Beltrandi, 2018). Several models
have been proposed in an attempt to arrest the situation. However, several concerns have been
raised from several quarters as to the capacity of the models to delineate the position and come
up with an ecologically sustainable solution. The Caribou issue is by far a simple one due to the
existence of some concerns. For instance, there is the plight of companies and persons who
depend on forests for economic activities such as oil exploration corporations. Attempts by the
government to use force by issuing a deadline to states to institute forest protection act as a way
of preserving Caribou habitat has failed. The best example is the State of Alberta that has
promised that it will fight such an attempt (Crydermarn, 2018). One of the reasons previous
models have failed is that there are two species, man and the Woodland Caribou, that have not
managed to co-exist together because one has overexploited the habits of the other. As a result,
there is the dilemma of coming up with a solution that will be favorable for both species. The
paper describes two models that can find a sustainable solution to the problem.
The reason the current strategies employed by the government under the SRA is that
some stakeholder feels that they have been left out in the model, or the mode threatens some
aspects of their interests. Animal, human conflict is not a new ecological phenomenon. Although
it is the responsibility of the government to protect wildlife in Canada, it cannot succeed without
involving various stakeholders and possibly the locals. Stewardship and education is a model
aimed at motivating the active participation of stakeholders and local communities. However, it
is essential that every party has a clear understanding of the primary objective and that issues
arising are addressed adequately.
The first approach will entail holding round table talks with locals and stakeholders to
collect their views on what they feel about being involved in the protection of Woodland

Caribou. These meetings will form a perfect platform to understand, and perhaps address the
issues of stakeholders such as oil exploration companies. Communities living close to Caribou
habitats or companies that use these habitats can be turned from potential environmental
stressors to parties that can support the program. Forceful and misguided restrictions will only
function to escalate the problem. The best approach, in this case, would be one that causes
minimal disturbances for both human beings and the sedentary Caribou. Sedentary Caribou does
not move around much. Therefore, there is the possibility of creating community managed
enclosures for the animals. The approach was successfully used in Sand County which now
enjoys community owned ranches with various species such as black bears, bald eagles, and
deer(Shogren & Tschirhart, 2001). The most important thing is educating the communities and
then giving them the responsibility of managing the ranches. Training should entail essential
considerations such as the possibility of turning the Caribou into a cash crop by selling Caribou
meat as a way of controlling the population once the threshold has been attained.
The second approach is habitat protection. The primary objective for habitat protection is
to ensure that the habitat for the Caribou is duly protected. The woodland Caribou often stay in
bushes where they primarily feed on trees. Therefore, when trees are felled for economic
purposes for the construction of roads or other activities such as oil exploration, it creates an
ecological problem. To ensure that the species is duly protected it is essential that the habitat for
the Caribou is duly protected. Therefore, the primary objective for this model is to ensure that
woodland areas that offer the perfect habitat for the Caribou get protected. Human practices are
the primary cause of the decline in the population of the Caribou. The Caribou is a sedentary
species that seldom move around. Furthermore, they mostly feed on trees, especially during

winter. Therefore, the primary objective of this approach is to ensure that human activities in the
localities where the Caribou reside get protected.
2. Answer to Question 1B
Perturbations as a result of human activities such as logging, oil and gas exploration, the
construction of roads, and other activities have either destroyed or fragmented Caribou habitat
thereby exposing the animals to predators or putting them in direct conflict with other species
such as deers that migrate from place to place. Therefore, to create a minimal ecological
disturbance of the species, it would be necessary to enclose the animals. The good thing with the
approach is that Woodland Caribou are sedentary and do not move around much. Local
communities will be educated on simple ecological management of the ranches, such as how to
monitor the populations and ensure that population threshold gets attained. Once the threshold is
achieved, and the animals are removed from the SRA list, then necessary measures can be taken
to keep the population in check. However, at the beginning promoting parturition and protecting
adults should be a key priority. Figure 1 shows a diagrammatic representation of the model that
will be implemented once the pre-test stage demonstrates that it is feasible and all the resources
have been mobilized. The primary objective of the approach is to ensure that the local
communities and other stakeholders can take an active role in the protection of endangered
species. Educating local communities to be responsible for the wildlife around is important
because it will reduce disturbances and ensure that they understand the primary objective of
conservation.
Skills

Baseline Survey Pre-Test
Knowledge
Attitude
Attitude
Active EEPES
Initiation Phase
Active
classroom
lessons
Hands-on-
activities
Field Exposure
Service
learning, small
projects, and
Practical
Baseline Survey Post-Test
Knowledge
Attitude
Skills
Attitude
Program for the protection of endangered species,
Woodland Caribou

Figure 1: Environmental Education for the Protection of Endangered Species (EEPES)
In habitat protection the first step that will be taken using this approach is to identify the
habitat occupied by the Caribou. Identification of the specific areas occupied by the species is
vital to assess the level of disturbance that has been inflicted that is perhaps causing a reduction
in the population. According to Panza-Beltrandi (2018), human activities are the major cause in
the reduction of the number of Caribou in Canada. Apart from illegal hunting that directly kills
the species, there are also other approaches such as the building of roads that have exposed the
animal to predators. Therefore, after the identification of the habitats, the next step will be to
come up with strategies to restore the destroyed areas and ensure that the current localities are
protected. The protection of habitats will require sacrifice from various stakeholders. For
instance, the companies that explore oil will be made to understand that some of their areas of
interest form the primary habitat for the Caribou. Therefore, they will have to hand over some of
these regions to the authorities for protection.
To protect the population of the Caribou, it is essential that the places that form their
primary homes are protected. Human beings have been identified as a stressor in this perspective.
Therefore, it is crucial to consider the role played by human beings in the process to ensure that
there are minimal disturbances once the project has been implemented. There are many projects
that will be sacrificed in the process. However, once everyone understands the importance of
environmental protection, it will be easy to convince the affected parties. The most probable
opposition to the program will come from people who are already benefitting from the places
that have been identified as the principle habitat for the Caribou. Therefore, this model will seek
to institute a proactive approach that ensures that states comply with the directive of the

government. As stated by Panza-Beltrandi (2018), there is no time for discussions because the
number of Caribou are dwindling fast. The time for action is now, and it will require the input
and goodwill of all parties involved to ensure that they comply with the directives. The task will
need increased funds for the project because some parties claim that the lands serve as a primary
source of income. Therefore, as stressed by Crydermarn (2018) the venture will require the
federal government to invest more money in the venture. The federal government already has
plans to ensure that the state governments comply. However, the state governments are also
complaining that the conditions placed by the federal government are not sensitive to the plights
of the people living in the localities of the endangered species. Therefore, there is a need for the
federal government to compensate the affected parties to ensure that they will no longer be
disturbances to the species. Figure 2 shows the strategy tha will be employed in the
implementing habitat protection for the Woodland Caribou.
Problem Formulation
- Critical habitat of
concern
- Stressor
Co-
occurrence
scoping
Exposure
scoping
Effects
scoping
Identify Communities
-listed species
Develop
protection
community model
Identify
focal
species
Data analysis
for focal species

Figure 2: Habitat Protection Strategy
The Woodland Caribou has been listed as an endangered species, implying that the
number of animals in the population is reducing at an alarming rate. Therefore, there is need to
come with ecological models that will ensure that the species does not go extinct. However,
much of the proposed models have encountered oppositions because the government has not
been sensitive to the plights of the locals and other interested parties. One of the proposed
models to deal with the situation is stewardship and education. The logic behind the propositions
is to educate the locals and other stakeholders on the importance of protecting the endangered
species.
Furthermore, the model aims at giving the locals an active role in the management of the
project through the establishment of enclosures that will act as homes to the species.
Stakeholders will be required to surrender a portion of their settlements and erect a perimeter
fence to reduce the level of disturbance. The second approach is to emphasize the protection of
the habitat occupied by the Caribou. These two strategies can help in the protection of the
Woodland Caribou.
Risk characterization for
focal species

References
Crydermarn, K. (2018, March 19). Alberta pushes back against federal caribou protection plan.
Retrieved from The Globe and Mail:
https://www.theglobeandmail.com/canada/alberta/article-alberta-pushes-back-against-
federal-caribou-protection-plan/
Panza-Beltrandi, G. (2018, December 8). N.W.T. government not acting fast enough on caribou
crisis, says MLA. Retrieved from CBC News:
https://www.cbc.ca/news/canada/north/nwt-government-caribou-1.4937589
Shogren, J. F., & Tschirhart, J. (Eds.). (2001). Protecting Endangered Species in the United
States: Biological Needs, Political Realities, and Economic Needs. Cambridge, UK:
Cambrige University Press.

E. Coli and Disease Transmission
Escherichia coli is a species of bacteria that are gram-stain negative and rod-shaped. This
species of infectious bacteria commonly resides in the lower intestines of healthy human beings
or warm-blooded animals (Zahera et al 2011). Generally, most species of the bacteria are less
harmful to humans but a few strains of the bacteria such as E. coli O157: H7 can be harmful thus
instigating indicators of austere abdominal cramps, nausea, vomiting, bloody diarrhea and
dehydration (Zahera et al 2011). Depending on the E. coli strain and type of infection, some of
the bacteria species can be contagious while others are not. Escherichia coli consists of diverse
species of bacteria. The pathogenic strains are categorized into pathotypes with six of them
associated with diarrhea condition and are often referred to as diarrheagenic E. coli (Jafari,
Aslani & Bouzari, 2012). According to Jafari, Aslani & Bouzari, (2012), the six pathotypes
associated with diarrhea include; Enterotoxigenic E. coli (ETEC), Shiga toxin-producing E. coli

(STEC), Enteropathogenic E. coli (EPEC), Enteroinvasive E. coli (EIEC), Enteroaggregative E.
coli (EAEC) and Diffusely Adherent E. coli (DAEC).
Escherichia coli 0157: H7 was first officially diagnosed and described as a cause of
illness in 1982 in the course of an epidemic of hemorrhagic colitis which was linked to the
consumption of hamburgers from a fast food joint (Stein & Katz, 2017). Ever since then, Riley
(2004) points out that the bacterium has been distributed globally hence triggering epidemics
with a significant number of the outbreaks being community-acquired and spread by the
foodborne and waterborne courses. A study conducted in 2007 by the Department of Animal
Biotechnology at the University of Nevada Reno identifies that in the past three decades, there
has been an insurgency in the epidemic rates of Escherichia coli 0157: H7 infections (Hussein,
2007). The findings of the global assessment of the beef cattle role in human infection identify
that, "The prevalence rate ranged from 0.1 to 54.2% in ground beef, from 0.1 to 4.4% in sausage,
from 1.1 to 36.0% in various retail cuts, and from 0.01 to 43.4% in whole carcasses…. With
regard to beef cattle, the prevalence rates of E. coli O157 ranged from 0.3 to 19.7% in feedlots
and from 0.7 to 27.3% on pasture” (Hussein, 2007, p.65). Exposure or infection from E. coli can
result from contaminated food or water and exclusively undercooked ground beef and unclean
vegetables. Signs and symptoms of the infection begin to exhibit three or four days after
exposure to the bacteria. The E. coli bacteria can instigate an infection even when small or
minute portions of the bacteria are ingested such as eating a small piece of undercooked meat or
drinking a mouthful of contaminated water (Bono et al., 2007). Globally, enteropathogenic E.
coli (EPEC), is identified as an endemic health threat that causes the deaths of several hundred
thousand people annually in developing countries (Hardwidge, 2003). An isolated occurrence of

enterohaemorrhagic E. coli (EHEC) has also often been reported in developing economies with
the causes identified to be contaminated hamburgers and water (Hardwidge, 2003).
Escherichia coli O157: H7 and other serotypes of the STEC family are naturally
contagious infections that have been widely recognized in a continuum of animal species
including cattle, moose, swine, goat and even chicken (Beutin et al., 1993). A substantial
prevalence ratio has been identified in cattle as a key reservoir of STEC strains which are
considered contagious to human beings as their hosts. In humans, the Escherichia coli O157: H7
contaminations usually occur when a contaminated host is consumed and most likely from intake
of cattle beef (Beutin et al., 1993). A significant number of human infections occur as a result of
the secondary spread of the strains. For instance, according to an examination of 90 established
E. coli O157: H7 epidemics that ensued between 1982 and 2006 in Ireland, Japan, Great Britain,
Canada, and the U.S, Snedeker, et al (2009) reports that 20% of the outbreak cases were a result
of secondary infections. Snedeker, et al (2009) point out that 54% of the secondary spread was
attributed to food and dairy products, water and the environs catered for 10% of the spread while
animal contact tailored 8% of the secondary spread. Transmission of the disease is largely
impacted by the consumption of any food or beverage that is contaminated with animal products
such as dairy products, meat, and manure/feces (Snedeker, et al (2009). Over the past years, the
sequence and model of outbreaks of Escherichia coli O157: H7 contaminations have
significantly changed. According to Chekabab et al (2013) fresh greens, fruits, and vegetables
have surprisingly become considerable sources of human Escherichia coli O157: H7 infections.
In the U.S alone, Xicohtencatl-Cortes et al (2009) reports that E. coli O157: H7 infections from
contaminated greens and fruits astoundingly augmented from 11% to 41% between 1998 and

2007. Contamination of these farm produces was largely attributed to animal feces that came into
contact with agricultural irrigation water.
Most recently in the spring 2011 European Escherichia coli O157: H7 contaminations
outbreak, King, et al (2012) indicates that the potential source of contamination was highly
attributed to greens which were either consumed raw or undercooked. The outbreak for the E.coli
disease transmissions globally has been associated with food and beverage consumption which
further raises concerns on the epidemiological and biological underpinnings of food and the
environment. For approximately the past three decades, non-O157 STEC has also largely been
linked with food-associated outbreaks. Analysis of scientific evidence has subsequently
identified that E. coli non-O157 strains are highly prevalent in meat products and have the
potential to instigate austere food-borne infection outbursts (Newell et al., 2010). According to
an analysis of levels of non-O157 STEC conducted by Hussein (2007) on cattle it was identified
that, cattle carcasses contained 1.7–58% of the strain, retail beef cuts 11.4–49.6%, ground beef
2.4–30% and the beef sausages contained 17–49.2% of the identified strain. Chekabab, et al
(2013) argues that “STEC non-O157 are less likely than O157 STEC to cause outbreaks or
severe disease, and because they are more challenging diagnostically, many non-O157 infections
may not be investigated fully, and their sources may thus remain undetermined” (p.1). Stigi, et al
(2012) point out that incidences of non-O157 STEC outbreaks have significantly evolved and
diverse tests have been conducted. It has been determined that the consistency in non-O157
outbreaks is largely attributed to its environmental persistence.
According to Bruneau et al (2004), a significant number of Escherichia coli O157: H7
outbreaks have been attributed to consumption of contaminated water. The scholars identify that
for instance, in 1999, a significant number of persons in New York and Washington County were

diagnosed with Escherichia coli O157: H7 infections after consuming contaminated water.
Another lot was diagnosed in Clark County and Washington County after swimming in
contaminated water. Hrudey et al (2003) point out that the Escherichia coli O157: H7 outbreak
that occurred in Walkerton, Canada 2000 was due to consumption of contaminated water by
feces and it instigated 2300 diseases in the region. An analysis of the diseases identified that
Escherichia coli O157: H7 and Campylobacter jejuni were pathogens responsible for the
infections. It was identified that surface bodies had largely been contaminated by E. coli O157:
H7 pathogen after heavy rainfalls and snowmelts which overflowed onto animal feces and
manure thus contaminating the surface water bodies (Bruce, 2003). A variety of human-to-
human infections were also reported in public spaces such as swimming pools and lakes. Bruce,
(2003) identifies that cases of children with diapers or people with diarrhea after shedding off
could contaminate these public spaces and cause human to human infections.
There exist some strains of E. coli O157: H7 that formulate biofilms on both biotic and
abiotic planes outside their hosts including polystyrene, stainless steel and polyethylene (Rivas,
Dykes & Fegan, 2007). The genetic appliance behind the formation is an intricate course
associated with the production of long polar fimbriae, features determined by genes supported by
O island OI-1, cellulose, and colanic acid (Allison et al., 2012). The Escherichia coli O157: H7
biofilm formation is also largely associated with the manifestation of some virulence genes. The
E. coli O157: H7 has diverse ranges and its shedding can be done through cattle feces whereby
they can persist and be recycled in agricultural environments, soil or water. Irrespective of the
water surface, whether oligotrophic surface water or groundwater, they should all be considered
as potential sources of E. coli O157: H7. Allison et al (2012) point out that the environmental E.

coli O157: H7 can manifest in different forms and when the circumstances and nutrients
conditions are satisfactory, phenotypic suppleness sanctions them to customize biofilms.
Below is an imagery illustration of the ecological habitat and spread of Escherichia coli
O157: H7 in a universal network. An examination of the image identifies that the On-farm cattle
are the key sources for the E. coli O157: H7 and are most probable to contaminate the
neighboring environs which include the feedlot and sewage through their fecal excretions
(Munns et al., 2015). Also, the consumption of their products can be a likely source of
transmission. The animals' close surroundings and manure dumped on lands is likely to pollute
the immediate water bodies most probably after a heavy rain pour. Additionally, the soils
polluted with toxic waste and teeming of drains contaminate the water bodies. As a result, the
sequence of events is likely to lead to contamination of plants which include farm produces
meant for human consumption. Also, the soils and water free-living protozoa may function as
flight paths for E. coli O157: H7 (Munns et al., 2015). The contaminated water bodies are also
likely to cause human infections through either recreational activity such as swimming and as a
source for human consumption.

Figure 1. An imagery demonstration which portrays the ecological habitat and transmission of Escherichia coli O157: H7 in a
global ecosystem
Virulence and Dispersion of Escherichia coli
There exists an array of elements that influence the dispersion and transmission of
Escherichia coli pathogens. Munns et al (2015) identifies that dispersion of Escherichia coli by
bovine species can be categorized into three arrangements which include the bacterial strain, the
animal host and the environment. Chekabab et al (2013) point out that pathogenic E. coli strains
have the capacity to last in exposed environs. Their survival in open environments is supported
by their ability to utilize nutrients and confer themselves to surfaces. For instance, Escherichia
coli O157: H7 is found in soils, manure, and contaminated seeds. These pathogens can also
colonize and reside in the internal organs of a plant thus making it difficult for a farmer to either
disinfect a plant or kill it. Escherichia coli pathogen that originates from animal fecal excretions

is understood to survive on grass pastures for approximately not less than 5 months thus making it
possible for E. coli O157: H7 to be consumed again by livestock. Stein & Katz (2017) point out that
even after being exposed to over more than 10 E. coli O157: H7, cattle livestock often remain
asymptomatic which makes them potential threats as carriers of these pathogens. The risk factors
associated with livestock as carriers include their age, weaning, shipping, season and potency of
these pathogens to lust within the feeding environments (Fairbrother, & Nadeau, 2006).
The virulence mechanisms of the Escherichia coli strains have recently become better
understood because of the introduction of molecular and cell biological designs that have been
prompted by diverse scholars. The pathogenesis of Enteropathogenic Escherichia coli largely
depends on the formation of the ultrastructural lesion where the bacteria make intimate contacts
with the host’s apical enterocyte membrane (Clarke et al., 2003). This contact between the
ultrastructural lesion and the host’s apical enterocyte membrane results in gross cytoskeletal
readjustments mainly the development of an actin-rich cup-like plinth at the place of bacterial
interaction also known as the attaching and effacing (AE) lesion (Nataro et al., 1985). Formation
of this AE lesion consequences to decrease in the ingestion aptitude of the intestinal mucosa
which ultimately results in interruption of the electrolyte balance and consequently to diarrhea
(Taylor et al., 1986).
In an analysis of the bacteriological dynamics convoluted in super-shedding, Stein &
Katz (2017) point out that numerous studies have recognized that E. coli O157 phage type 21/28
(PT 21/28) is a pathogen that largely increases bacterial shedding. The foundation that enlightens
association between the pathogen and shedding is not adequately determined. However, Chase-
Topping et al (2008) suggest that E. coli strains to embrace PT 21/28 confer variations in the
manner the microbial category III secretion structure (T3SS) is controlled, and that these

variations may perhaps sanction extra widespread bacterial annexation and secretion. Among
livestock cattle that are plague-ridden with E. coli O157: H7 pathogen, virulence dynamics that
fit in the T3SS set are vital for intestinal annexation and for extended bacterial shedding (Stein &
Katz, 2017; Sharma et al., 2012). A study conducted to survey whether the E. coli O157: H7
strain category is associated to super-shedding, the researchers assembled fecal pads from
approximately 3500 cattle in the course of the summer months of 2009 and 2010 (Arthur et al.
2013). The examination identified that in E. coli super-shedder strains, the T nucleotide was
dominantly existent at position 255 of the tir gene than the A nucleotide which represented a
percentage ratio of 71% vs 29% (Arthur et al. 2013). Bonno et al (2007) identify that initially,
"the T255A tir allele at this position was found in >99% of 108 human clinical isolates examined
and in 55% of 77 bovine isolates, suggesting that it could provide a bovine ecological niche for
the bacteria” (p.98).
Stein & Katz (2017) point out that there are cattle-specific factors that are involved in E.
coli O157 super-shedding. One noticeable factor identified is the spreading rate of the cells from
the cattle gastrointestinal tract. Magnuson et al. (2000) indicate that enhanced proliferation of the
cells to the colons raised the chances that the lower gastrointestinal tract of the cattle will be
colonized for longer durations as opposed to livestock with sluggish cellular proliferation
proportions. Another element that increases E. coli O157: H7 bacterial shedding as earlier
identified is animal transportation. Points out that dietary anxiety and food scarcity among
transported cattle may transpire when there is insufficient food or when the cattle refuse to feed
thus further increasing the shedding of bacteria. Cray et al (1988) point out that a study which
involved calves with 107 E. coli O157: H7 after a two-day duration of food scarcity conveyed
that vulnerability to infection and the shedding of bacteria were greater in the food-deprived

calves, as paralleled to calves that had been subscribed to a consistent dietary plan. A subsequent
study by Gregory et al. (2000) which examined the connection between fodder and gut bacteria
identified that cattle that had been deprived of food for a 24-hours period prior to transportation
had supplementary E. coli in the digestive paths including their rumen, small intestines, and
colon as opposed to those animals which had been administered to a consistent diet plan for the
past 48hrs.
Another significant factor involved in animal super-shedding is age. A study conducted
by Mir et al. (2015) identifies that heifers or cows aged one year or less had an expressively
inferior occurrence and lower shedding than cows aged 2 and above. The frequency of E. coli
O157 was maximum in 2-year-old cows, and average in older cows. An increased E. coli O157
prevalence and shedding ratio was linked to younger cattle age in beef cattle. An analysis of
dairy cattle identified that the shedding of VTEC was maximum in 2- to 6-month old heifers as
paralleled to those younger than two months old.
Conclusion
From the analysis of its transmission and virulence activities, the study has identified that
with the right nutrients and circumstances, the E. coli O157: H7 pathogen has the potency to
survive and remain persistent in many conditions. Apart from its potentials to cause human
infections, the E. coli O157: H7 has the ability to remain persistent in water and soil which
makes it a pathogenic bacterium that draws serious public health concerns. It poses a significant
threat to the environment and humans because it also has the ability to assume a food shortage
and persistence state that sanctions it to survive in low nutrients environments such as water. Its
diverse transmission and distribution mechanisms make it difficult to implement definite

strategies to mitigate contamination processes and rates. The most efficient and informed
strategy will be to standardize data collection and random sample methods in order to
comprehensively detect and ascertain its ecological habitation and distributions.

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