Download George Tarabelsi 5/4/14 The Gateway to Mankind`s Deadliest

George Tarabelsi
5/4/14
The Gateway to Mankind’s Deadliest Diseases: Zoonosis
Karl Marx states, “Medicine heals doubts as well as diseases,” yet the days continue to go
by with no cure to these diseases leaving society doubtful. Emerging viruses are continually
making news’s headlines due to their catastrophic impacts, and it’s all due to zoonosis. Zoonosis
is a disease or infection that is naturally transmissible from vertebrate animals to humans, and
vice-versa. The disease is caused by all types of pathogenic agents, including bacteria, parasites,
fungi, and viruses. Humans can get zoonotic diseases by coming into contact with the infected
live poultry, rodents, reptiles, amphibians, insects, and other domestic and wild animals. Anyone
who has contact with animals can get a zoonotic disease, but people may be more at risk than
others may. These include people with a weakened immune system, children age five, the
elderly, and pregnant women. Zoonosis has received recent attention from the news and media,
specifically in cases of Ebola, H5N1, and H1N1. It is vital to explore the biological mechanisms,
which allow these viruses to expand their host range. In addition, examples of these diseases will
better illustrate the wide range of consequences these viruses can exhibit, from mild to
detrimental.
The way that a virus transmits from an animal to a human is important in the overall
understanding of how to cure and prevent these deadly diseases. First, the infection of a virus
occurs in four steps: an initial exposure to the virus, infection by the virus from a host, spread of
the virus to other people, and adaptations that the virus acquires. Specifically, exposure to the
virus entails contact between donor and recipient hosts for transfer of the virus. Infection by the
virus encompasses that in order to infect a new host; the virus must infect the appropriate cells of
the new host. Spread of the virus to other people shows that the population density plays a large
role in the exposure to virus, and occurrence of epidemics. Finally, adaptations that the virus
acquires explains how though a virus can infect a host, there is medicine that can kill the virus. It
is clear that that infection is easily transmissible, so preventative measures should be strictly
enforced to prevent further expansion of such viruses.
Ebola has recently received much attention due to its recent surge of infection in parts of
Eastern Africa. Ebola virus is transmitted from animals to humans via blood contact with an
infected animal host and lesions in the hands of a human. The virus then affects the blood of its
new host. This then transmits from human to human through direct contact with blood or bodily
fluids from another infected person. Also, the virus can be spread via contaminated medical
equipment such as shots and needles. In addition, there are currently four strains of Ebola known
to be able to infect humans and most cases have developed in remote areas of Africa (WebMD).
Ebola is a threat to patients and doctors dealing with the disease because it has killed 90% of
those infected (CNN.com). Besides trying to keep the patient hydrated and well, there are no
known treatments for those infected, which may explain the high rate of death. An individual
coming in contact with the bodily fluid of an infected individual spreads the disease
(USAToday). However, the disease may originate from an individual coming into contact with
the excretions or blood from animals infected with the disease (WebMD). Symptoms of infection
develop relatively quickly and begin to appear “2 to 21 days after infection,” (CNN.com). The
early signs include “a rash, red eyes, hiccups, chest pains and difficulty breathing and
swallowing” (CNN.com). As infection progresses symptoms lead to vomiting, diarrhea, impaired
kidney and liver function and sometimes internal and external bleeding” (CNN.com).Ebola virus
feeds off a large population, so the larger the population the worse the effect of the virus.
Preventative methods include, staying out of areas affected by the virus and maintain proper
sanitation along with remaining hydrated and addressing any wounds or rashes that appear due to
disease. In addition, viruses have emerged to resist more human made prevention methods such
as vaccines and antibodies. In the past, viruses would infect a small population and become
extinct after the population had died off as it fed off the population for fuel. Now with larger
populations throughout the world the spread of the Ebola virus is extremely dangerous and needs
to be tackled in order to prevent the deaths of human lives.
Another virus that is effecting many after its recent revival is, Avian Influenza (H5N1 Bird
Flu). Avian Influenza is a highly pathogenic avian bird flu virus, which has caused outbreaks in
parts of Asia and the Middle East over domestic poultry. The virus was first detected in China in
1996 from a goose, and currently no proof that the virus can spread from human to human, but
possible adaptations pose threats. Also, it is estimated that about 650 human cases have been
reported from 15 different countries since 2003, and the mortality rate is about 60% of those
infected with the virus. Symptoms and complications of those infected with H5N1 include, fever
and cough, acute respiratory distress, shortness of breath/difficulty breathing, abdominal pain,
diarrhea, pneumonia, respiratory failure, shock, altered mental state, seizures, failure of multiple
organs (e.g. kidney failure), and death. Moreover, treatments and vaccinations include, two
antiviral medications previously licensed by the FDA have shown resistance to HPAI H5N1, and
it has been recommended to use either oseltamivir or zanamivir. Similarly, Zoonotic Avian
Influenza along with other viruses spread once it overcomes the three different barriers order to
spread from one species to another. First, is cross-species host-host interaction, which refers to
the species from which the virus originated and the species that received the virus would have to
interact initially. Second, virus-host interactions, which refers to the ability of the virus to infect
the nest host species. Finally, are interspecies host-host interactions, which is the transferring of
the virus between infected and non-infected hosts within the species. Also, infection of Influenza
virus is dependent on the species of the bird and how pathogenic the virus is; H5N1, for
example, has high pathogenicity. Highly pathogenic viruses are always of the H5 or H7
subtypes, even though not all H5 or H7 subtypes are highly pathogenic. Highly pathogenic
viruses are “characterized by an HA protein with a cleavage site containing multiple basic amino
acids, which makes the protein cleavable by proteases ubiquitously present throughout the body
rather than only those present at mucosal surfaces.” Avian Influenza is easily transmissible and
deadly, which supports the idea of focusing harder on cures to these zoonotic diseases.
A couple years ago, there was pandemic of H1N1 Virus (Swine Flu), which caused many
deaths and scared a large population, and it should. The H1N1 virus is an orthomyxovirus that
contains the glycoproteins Haemagglutinin and NeuraminidaseCommon throughout pig
populations worldwide. Haemagglutinin is a glycoprotein, which causes red blood cells to clump
together, and then it binds the virus to the infected cell. Neuraminidase are enzymes that assist in
transferring the virus particles through the affected cells and help in growing from the host cells.
This results in severe respiratory illness in pigs. In addition, people with daily exposure to pigs
are at high risk of swine flu infection; however, transmission from pigs to humans is not
common as it was declared a flu pandemic in 2009 in the United States. The virus appeared to be
a new strain of H1N1, which resulted when a previous triple re-assortment of bird, swine, and
human flu viruses further combined with a Eurasian pig flu virus (swine flu). Moreover, the
initial outbreak of swine flu was in Mexico, South America. The virus that normally circulates in
just pigs, altered so that humans could be affected with the same virus. This virus had two genes
from flu viruses that normally circulate in pigs, in Europe and Asia, three genes that normally
circulate in North American pigs, and genes from flu viruses from birds and people as well. The
method of transmission from pigs to humans (although very rare) is through air-borne droplets
from coughing or sneezing of an infected animal. Furthermore, while there is no treatment, there
are many measures of preventative care, such as getting a flu vaccine. Also, to prevent pighuman transmission of swine flu, farmers are encouraged to wear facemasks when dealing with
the infected animals and to wear gloves so the disease can’t be transmitted through hand-eye,
hand-nose, or hand-mouth transmission. Antiviral drugs can also be provided to make the illness
more “bearable.” The majority of people with the H1N1 virus make a full recovery without
acquiring medical attention or antiviral drugs. H1N1 revival is one that never should have been
celebrated or welcome, stressing the importance of containing and preventing such detrimental
occurrences.
The research of biological mechanisms allow these viruses to expand their host range, and
such examples like Avian Influenza, Ebola, and H1N1 illustrate the consequences these viruses
can exhibit, from mild to detrimental. Often, in order to be affected by a zoonotic disease, there
are four key steps: exposure to the virus, infection by the virus, transmission of the virus to
members of the population, and the adaptations the virus makes to infect others more effectively.
While we have advanced in understanding the effects of the virus, there are certain aspects that
we must continue to explore. These aspects include the study of when and where the virus forms.
In addition, we must work to understand what it is that causes the spread of the virus, and how
we can limit the virus' natural reservoir, which would in turn, limit the spread of the virus.
The development of a zoonotic disease occurs through the exchange between humans and
animals, and as a first defense against the development of these diseases, the exchange of bodily
fluids between humans and animals must be addressed. Not only to be sure that the exchanges
are humane, but also done cleanly in order to deter any more diseases from developing. In
conclusion, the four ways infection can be caused include: exposure to the virus, infection by the
virus, spread of the virus to other people, and adaptations that the virus acquires. Though much
work has been done on these viruses, we still need to study more about when and where the
viruses form, what causes their spread, and how to limit the virus’s natural reservoir. Finally, the
large health concern of the exchange of bodily fluids or blood between humans and animals must
be established quickly so that no more diseases may be permitted to develop. It is time for
society to come together and tackle this problem head first in order to eradicate the deadly
diseases that kill so many innocent people.
Works Cited
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2546865/- http://www.who.int/zoonoses/en/
- http://www.nairaland.com/1685706/no-outbreak-ebola-virus-nigeria/1
- http://www.cnn.com/2014/03/27/world/ebola-virus-explainer/
- http://www.webmd.com/a-to-z-guides/ebola-fever-virus-infection
- http://www.usatoday.com/story/news/nation-now/2014/04/07/ebola-africa-explaineroutbreak/7411889/
- http://www.cnn.com/2008/WORLD/africa/12/08/pip.zoonotics/