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Epidemiology Research Project

Anthrax

April 16, 2012

HSC 387

Melissa DeArmond, Ben Guthrie, Chaz
tan

Moore, Emily Sullivan























2


Disease Profile



According to the U.S. Centers for Disease Control and Prevention (CDC), anthrax is an
infectious disease caused by a bacterium known as
Bacillus anthracis

(CDC, 2009a). This disease is
most commonly found in farm animals such as pigs, sheep, cattle, and ho
rses; however, in rare
instances, anthrax can occur in humans. Because anthrax is found most commonly on these animals,
farm workers, veterinarians, lab workers, tannery, and wool workers are more susceptible to contract the
disease. If anthrax is used as
biological weapon, law enforcement, public health, and healthcare workers
are at risk of exposure as well (CDC, 2009a). Within the environment, the anthrax bacterium creates
spores that can live in the earth’s soil for several years. There are three common

ways for people to
contract anthrax: (1) contact through a break in the skin (e.g. cut or scrape), (2) eating meat that is
undercooked, and (3) inhaling the bacterium spores. Although anthrax is contracted through these
factors, the disease is not found t
o be contagious, meaning it cannot spread from person to person. The
three main types of anthrax are cutaneous, intestinal, and pulmonary (National Center for Biotechnology
Information, 2011; CDC, 2009a).

The most common type of anthrax is cutaneous, whic
h occurs when a person is infected through
the skin from handling animals or animal products that are contaminated from the bacterium (CDC,
2009a). A person that has contracted this type of anthrax will develop sores that evolve into painless
ulcers with a

black coat located in the ulcer’s center. This infection has the potential to spread
throughout the body if left untreated (CDC, 2009a). Less common than cutaneous, but more dangerous,
is intestinal anthrax, which is contracted from the consumption of und
ercooked meat. Consuming meat
that is contaminated with the anthrax bacterium can result in an individual experiencing nausea,
diarrhea, vomiting, and bleeding from their digestive tract (CDC, 2009a). The exposure of anthrax
through inhalation is known as
pulmonary anthrax, which is the rarest and most severe of the three types
of anthrax infection. This type of anthrax is caused from inhaling spores of the bacterium through the
3


lungs. Beginning symptoms of pulmonary anthrax are very similar to the common c
old or the flu, but
then they develop into severe pneumonia and hospitalization. Cutaneous and intestinal anthrax
symptoms occur within seven days, while pulmonary anthrax symptoms can take several months until
an individual will feel any signs of infectio
n. (NCBI, 2011; CDC, 2009a).


There have been approximately 2,000 to 5,000 cases of anthrax reported worldwide; the United
States experienced its biggest bioterrorism anthrax threat in 2001. Following the events of the terrorist
attacks in New York City on

September 11, 2001, anthrax was deliberately spread in the U.S. postal
systems through contaminated letters that contained a powder substance containing the bacterium. More
than half of the twenty
-
two cases resulted in death due to the inhalation the bact
eria and contraction of
pulmonary anthrax. Threats of using anthrax as a biological weapon caused panic among schools and
postal services in the United States. School systems and communities were recommended to enhance
their knowledge of bio
-
terrorism, and

to equip the schools’ faculty members with the knowledge and
expertise to help prevent, respond, and manage any threats of anthrax and other bio
-
terrorism related
agents. Also in 2001, the United States postal service issued suggestions to residents on ho
w to detect
suspicious mail that might be contaminated with the anthrax bacteria (Mann, 2007).

Within the U.S. government and economy, research and money has helped develop an anthrax
vaccine. According to NCBI (2011), after the terrorist attacks on Septem
ber 11
th
, an estimated 500,000
U. S. troops were given anthrax vaccines in response to the release of the bacteria’s exposure amongst
U. S. civilians. This vaccine administration was done without approval from the U.S. Food and Drug
Administration (FDA), a
nd it was found that the vaccine resulted in an increase in joint symptoms, as
well as intestinal adverse reactions (NCBI, 2011). According to the National Vaccine Information
Center (2006), creating a lawsuit by many, a federal court judge issued a postpo
nement on using the
vaccination on U.S. troops. After years of controversy whether or not the vaccine is causes other health
issues, congress has questioned the ruling of the vaccine being safe and effective. At that time, this led
4


experts to believe that
it would be undesirable to use the vaccine with the general public. These beliefs
have created more debate amongst politicians’ decisions on whether or not the vaccination should be a
requirement for adults or if there needs to be a removal of the “experim
ental vaccine” version (NVIC,
2006).

Etiology


Characteristics

Bacillus anthracis

is a dangerous bacterium that is characteristically in spore form. These spores
lie dormant in the soil until they are in the correct environment, where they become activated and infect
the host with anthrax. Kolata, Broad, and Altman (2001) found that on
ce inside the host, the spores will
travel to the lymph nodes and develop into the anthrax bacteria. The bacteria will then begin to release
lethal toxins that will attack and kill the body’s cells and cause fluid buildup in the tissues. Once the
spores ha
ve germinated in the lymph nodes, it does not take a long time for the symptoms to begin to
appear. Symptoms typically appear anywhere between twelve hours to five days after exposure to
Bacillus anthracis
. There are three major types of anthrax; inhalatio
nal, cutaneous, and gastrointestinal
(NVIC, 2006). Each type has their own separate modes of transmission and risks for exposure.

Reservoir

Bacillus anthracis is typically found in agricultural and industrial settings (Sirisanthana &
Brown, 2002). Anthrax

is found worldwide throughout the soil and can infect many invertebrate
mammals and herbivores. Kolsto, Tourasse, and Okstad (2009) stated that this bacterium has existed in
the soil for more than 2000 years, but has recently been the forefront of researc
h due to the bioterrorism
attempts in 2001. Kolsto et al. (2009) said that the anthrax reservoir is in the soil, where it lies dormant
as an endospore. These endospores are extremely resistant to chemicals, heat, cold, and UV light. This is
the cells mecha
nism for protecting itself during long periods of environmental stress. Because of this
5


protection mechanism, spores have been known to live in the soil for as long as 48 years (Fishbein, n.d.).
These spores will remain in the soil until they can find a vi
able host.

Mode of Transmission


Inhalational
.
Inhalational anthrax is the most deadly form of anthrax, and is possibly the most
widely known due to the recent bioterrorism attempts. To obtain inhalational anthrax, one must breathe
in the spores of the ba
cterium. Once these spores have been inhaled, they will travel to the lymph nodes
where they will proliferate and spread throughout the body and blood stream and begin to attack the
internal organs (Kolsto et al. 2009). It’s also important to understand th
at anthrax cannot be transmitted
between people. Once a person is infected, that person cannot infect another person (Fishbein, n.d.).


Cutaneous.
Cutaneous anthrax is the most common form of anthrax and composes about 95% of
the cases. It is characteristi
cally noted by a small red
-
brown sore that will harden and grow into a skin
ulcer with a black center (Fishbein, n.d.). It is spread through the dermis, and can be transmitted if a cut
or a scratch on the skin comes in contact with infected animal tissues
or hides.


Gastrointestinal.

Gastrointestinal anthrax can occur in people who eat undercooked meat from
infected animals. Herbivores are human’s biggest exposure risk factor for getting gastrointestinal
anthrax. Consuming undercooked meat of an herbivore,

who often has its nose in the soil, is putting us
at a huge risk. Swallowing these anthrax spores can cause lesions from the mouth all the way down to
the cecum. They can also cause ulcerative lesions in the stomach, which could bleed and even
hemorrhage
in severe cases (Sirisanthana & Brown, 2002). The bacteria can also travel through the
bowel wall and spread toxin throughout the bloodstream, causing deadly septicemia (Fishbein, n.d.).

Risk Factors for Exposure and Infection


Areas where anthrax is most
prevalent are continents containing tropical and sub
-
temperate
regions (Sirisanthana & Brown, 2002). Those that contract anthrax usually reside in lesser developed
countries. It has become a rare occurrence in places such as the United States. It mostly oc
curs in
6


countries that do not have health regulations that prevent exposure to infected animals like livestock,
sheep, goats and horses (CDC, 2006
a
). Those that become ill with gastrointestinal anthrax do so by
eating undercooked meats from infected animal
s. Most developed countries have health code regulations
that prevent infected meat from being sold and consumed. Those that obtain cutaneous anthrax do so by
coming into contact with infected animal hides. Workers, who often handle animal hides such as an
imal
skinners, drum makers and leather tanners are at high risk for exposure (CDC, 2006
a
). Even those that
do these jobs in the United States often work with animal hides that have been imported from foreign
countries that may have let an infected hide sli
p by undetected. Even with strict regulations in place in
developed countries like the United States, cases of anthrax still occur.


Methods of Control


To control the spread of anthrax, certain guidelines and precautions must be implemented. There
are s
everal ways to prevent morbidity and mortality from anthrax; furthermore, there are various ways to
test for anthrax. Safety measures must be taken if anthrax is discovered in within population in the
United States. Several methods are utilized, includin
g systems and principles, to control the spread of
anthrax.


Effective treatment for anthrax is available. Individuals who test positive for anthrax have the
option to choose from a variety of treatments. Addanki
,

et al. (2011) describe an anthrax test

that
captures specific, target cells that are produced when an anthrax infection is present. To be more
specific, this test detects antibodies that are produced from the anthrax infection, which then results in a
positive screening for anthrax. The offi
cial name for this antibody test is named the Anthrax Quick
Elisa Test, but it is more commonly known as the ELISA test (
National Environmental Health
Association
, 2004). This is the first anthrax test approved by the U.S. Food and Drug Administration
and

it is an easy clinical tool used by health professionals.

7



Several other anthrax tests are being developed that do not rely on specific cell isolations or other
similar variables. Addanki, et al. (2011) have developed and explained a very sensitive tes
t which is
able to recognize an anthrax infection. This test is able to identify DNA sequences and toxins that are
associated with anthrax contamination. Furthermore, this test is more than one thousand times more
sensitive than the Elisa test, which mak
es its results significantly more accurate. Addanki, et al. (2011)
also explains that anthrax has become more bioengineered with advance toxins. An Elisa test may not
be able to detect bioengineered anthrax, but this new DNA test can easily recognize var
ious forms of
anthrax.


Other testing forms for anthrax include clinical screenings (Stern, Uhde, Shadomy, & Messonier,
2008). Screenings for anthrax inhaled in the body have very low sensitivity and detection. Specificity
of clinically inhaled anthrax

screenings is also low. This form of primary prevention is used when
symptoms of anthrax are persistent among a population. Clinical screenings for inhalation of anthrax
are also used when there is a large event or when a general group is at risk of an
anthrax infection.


If an individual is found infected with anthrax, precautions and certain guidelines are to be
applied. Addanki
,

et al. (2011) explains that antibiotics and a vaccine are used to treat the anthrax
disease. Forms of antibiotic treatme
nt include several medications, such as ciprofloxacin, doxycycline,
penicillin, and others; some of these medications are approved for all ages by the U.S. Food and Drug
Administration
(Stern, et al.

2008). Other forms of treatment include levofloxacin an
d specific types of
penicillin. Both forms of treatment are recommended to use as a secondary precaution and only when
needed (Stern,

et al.
2008). Resistance to these antibiotics may become an issue which would prevent
individuals to be cured of anthrax
. Without the anthrax vaccine, ciprofloxacin is to be taken by a
patient for eight weeks; with the vaccine, an infected patient only has to take the antibiotic ciprofloxacin
for four weeks (Addanki
, et al.

2011). The only licensed anthrax vaccine in the

United States is known
8


as the Anthrax Vaccine Adsorbed (AVA); combined with antibiotics, this vaccine helps treat anthrax
infection (Weiss, Weiss, & Weiss, 2007).

Animals also have the ability to become infected with anthrax, which is why vaccines for
l
ivestock and various animals have been created. The vaccine for the livestock of farmers is called the
live spore vaccine, which is licenses by the U.S. Department of Agriculture (Weiss, et al. 2007).
Mongoh, Dyer, Stoltenow, Hearne, and Khaitsa (2008) d
iscovered that anthrax infection most
commonly occurs in wild and domestic cattle, sheep, and livestock. Humans, such as farmers, can
contract anthrax through the handling of infected animals or animal parts (e.g. animal hides). Different
strategies are
used to prevent the spread of anthrax through animals. These strategies include movement
of livestock, disposal of infected animals, and quarantining of infected animals
(Mongoh, et al.

2008).
Many animals infected with anthrax are treated with the live s
pore vaccine, as well as antibiotics in
order to inhibit the spread of the disease through animal and human interaction.


The U.S. Centers for Disease Control and Prevention (
2006
)
concludes that anthrax vaccinations
are used in preparation for possible
attacks; these vaccinations are also taken with antibiotics for
successful treatment among at
-
risk populations during or after an attack. At
-
risk populations of anthrax
attacks include specific military personnel; there is a mandatory policy for anthrax v
accinations for a
t
-
risk militants (Weiss, et al.

2007).


If an anthrax outbreak has been identified, the infected individuals are to refer to a health care
professional. Clinicians are to screen the patients who are suspected of anthrax contamination an
d then
retain blood samples of those individuals who are infected before treatment is begun (Stern, et al. 2008).
Microbiologists and the local law authorities are contacted if an anthrax infection or attack is suspected
in the area.





9


Distribution


Current anthrax cases in the United States are few and far between. In the early 1900’s, the
annual incidence of naturally
-
occurring human anthrax in the U.S. was an estimated 130 cases; this rate
has significantly declined to fewer than 2 annual cases in
the early 2000’s (CDC, 2009
b
). However, an
unexpected outbreak in 2001 resulted in 22 cases due to a bioterrorism act in which
Bacillus anthracis

spores were distributed through the U.S. mail (CDC, 2009
b
). In addition to inhalation, anthrax can also
be co
ntracted through food and water contamination, as well as contaminated animal hides, which are
generally used for drum making (CDC, 2009
b
). Such a case occurred in 2009, when a 24 year old
female in New Hampshire contracted gastrointestinal anthrax as a r
esult from participating in a
drumming event where the unknown, contaminated animal
-
hides were used (CDC, 2009
a
). This case
was the first related to animal
-
hide drum exposures that involved the gastrointestinal form of the disease
(CDC, 2010). Similar case
s of anthrax associated with contaminated animal
-
hide drums have been
reported from 2006
-
2008; this reflects the low but potential risk for anthrax among individuals who
work closely with untreated animal hides and/or are exposed to anthrax
-
contaminated en
vironments
(CDC, 2006
b
; Anaraki et al., 2008; CDC, 2008).

As mentioned previously, national reported anthrax cases are very low. Twenty years prior, in
1992, there was one reported of case of anthrax in the U.S.

and the
age and sex of the individual

wa
s not
identified; please refer to Appendix A for the complete table (CDC, 2009b).

Five years prior, in
September 2007, there was also one reported case of anthrax in the U.S. in a male from 5
-
14 years of
age
; please refer to Appendix B for the complete ta
ble

(CDC, 2007). The most current report of anthrax
in the U.S. was the one case in 2009 in a 24 year old female which was mentioned previously
; please
refer to Appendix C for the complete table (CDC, 2009b)
. For all three mentioned cases, no additional
de
mographic, environmental, or time variables were given.
Please refer to Appendix D for a line graph
representing the number of anthrax cases from 1954 to 2009 (CDC, 2009b).

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Luckily, there have been no reported deaths from anthrax in the U.S.

in recent yea
rs.

Furthermore, there are no reported cases of anthrax in the state of Indiana.


Conclusion

Anthrax is a serious infectious disease that must be properly addressed upon exposure. Because
the overwhelming majority of anthrax cases occur in animals, it is a
dvised that individuals
should
avoid
exposing themselves to

any animal or animal parts that may be contaminated with the bacterium. The
type of exposure, whether it is cutaneous, intestinal, or pulmonary, determines the level of severity of
the case. Treatment levels also vary depending on the type of anthrax
infe
ction
. Public health officials
must be wary of potential bioterrorism acts involving anthrax, because the results could be devastating.
Due to new levels of bioterrorism threats, prevention methods and an anthrax vaccine have been
implemented. The health r
isks associated with the aforementioned preventative measures are uncertain
and should be used with caution.
Although rates of anthrax cases in the U.S. are very small, and even
smaller in the state of Indiana, improper diagnosis may lead to mortality.













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-
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