There is a lot of news lately regarding the Ebola virus. How
it is spreading and how dangerous it is. However, this virus is similar to
another virus, the Marburg that can affect the body in similar ways. For
example, signs and symptoms usually begin within 5 to 10 days after the
infection with Ebola or Marburg virus has occurred.
The
Filoviridae virus family.
There are three virus members in the Filoviridae family. The
Genus EbolaVirus, is one, and the genus Marburgvirus and genus Cuevavirus are
the other two.
Genus Ebolavirus is made up of 5 distinct species:
Bundibugyo ebolavirus
Zaire ebolavirus
Reston ebolavirus
Sudan ebolavirus
Taï Forest ebolavirus
The Genus Marburgvirus is made up of 2 distinct species:
Marburg
virus and Ravn virus
The most recent genus is the Cuevavirus addes in 2010.
In general,
what are these viruses?
The Ebola and Marburg virus are related because they cause
severe fevers. These are illnesses marked by severe bleeding called a
hemorrhage. There is also the possibility of organ failure and, which can cause
death. Both viruses occur in Africa where these outbreaks have occurred for
decades. Marburg virus and Ravn virus (2), which are approximately 20%
divergent from one another
What are
some of the effects of these viruses?
The effects include fever, joint and muscle aches, severe
headache, chills, and body weakness.
However, after a time, the symptoms become more severe and
additional body impacts occur such as nausea and vomiting, chest pain and cough,
diarrhea, rash, stomach pain, severe weight loss, and red eyes. In addition,
other bleedings may occur. Some will come from the eyes, and also bruising can
occur where people near death may bleed from other areas like ears, nose, and
rectum.
Causes of
the viruses spread
Both Ebola and
Marburg virus originate from animals. Both have been found inside African
monkeys, and chimps in addition to non-human primates. There also has been some
evidence linking the Marburg virus to fruit bats in Africa.
How does the transmission from animals to humans
occur?
At this time,
the science evidence points to infections that occur from both viruses, which
have infected transmissions to humans through the animal's bodily fluids.
Examples include:
Blood products. When people butcher or eat infected animals
this can spread the viruses. While carefulness is important, and as part of
their research, even scientists who have operated on infected animals have also
contracted the virus.
Animal waste products also form a basis of transmission.
Tourists who have entered African caves and mine workers working underground have
been infected with the Marburg virus, in part because they have had contact
with infected bats and their spillover like the feces or urine.
At this time, there's no evidence that either the Ebola virus
or the Marburg virus can be spread from insect bites.
How does the transmission from person to person
occur?
Infected
people ordinarily do not become contagious until after they develop symptoms.
Family members, however, can become infected as they care for sick relatives or
prepare a burial for the dead.
The Death
Rate
Why are these
viruses are so deadly? It involves the immune system. These viruses interfere
with the system's ability to protect the body. Both Ebola and Marburg can lead
to a high percentage of death for infected victims. The current death rate is
90%. So what happens to people that are infected? The virus can cause multiple
organ failure, severe bleeding, coma, shock, jaundice, seizures, and delirium.
One of the current science and medical mysteries is that it
is not clear why some people recover from Ebola or Marburg virus but others do
not.
The
Evolution of the Ebola and Marburg Virus
While media attention has been focused on the deadly aspects
of these viruses, another science and evolutionary aspect is present.
These viruses are relatively new.
Ebola first appeared in 1976 in simultaneous outbreaks located
in Nzara, Sudan, and in Yambuku, in the Democratic Republic of Congo. Because
Yambuku is a village situated near the Ebola River, the disease takes its name
from there.
As these diseases originated with similar DNA sequences, what
became important is how they continue to spread. It turns out that RNA is the
prevailing sequence. In studying the DNA for Filoviruses, it became understood
that they reproduce as RNA. The instance then showed that even though they
reproduced over 20 years when they were first studied from 1976 to 1996, the
original RNA format was stable.
One of the operating standards regarding these viruses is
that the evolution originated with animals, but the virus found a steady and
consistent approach to spreading inside the body of the animals. It didn’t
change over time.
However, at the DNA level, how often is there a substitution?
The following table give a general description:
The changes shown by the molecular evolutionary rate identify
the rate.
Looking at the molecular evolutionary rates for viruses
belonging to different species range from 0.46 × 10(-4) nucleotide
substitutions/site/year for Sudan ebolavirus to 8.21 × 10(-4) nucleotide
substitutions/site/year for Reston ebolavirus.
What this means is that the changes, which are the nucleotide
substitutions, occur very rarely. A nucleotide mutation alters the amino acid
sequence of a protein.
So the most recent common ancestry can be traced back only
within the last 50 years for two viruses the Reston ebolavirus and the Zaire
ebolavirus species. What this suggests is that viruses within these species may
have undergone recent genetic bottlenecks preventing them from acting. On the
other hand, viruses within Marburg and Sudan ebolavirus species can be traced
back further and share most recent common ancestors approximately 700 and 850
years before the present, respectively. However, scientists looking at the
whole family of virus have presented suggestions that members of the
Filoviridae virus share a recent common DNA ancestor originating approximately
10,000 years ago.
Summary
Both Ebola and Marburg viruses originate with animals in
Africa. Contact with the animals will spread the virus to humans. Humans can
spread the virus to other humans if either one encounters another person and
then gets exposed to human fluids. The overall consequences can be deadly. At
this time, there is no cure.
The evolution of the viruses can go back to 10,000 years for the Filorivide, and 700 to 850 years for versions of the Ebola and Marburg virus and most recently 50 years for the other versions of the Ebola virus.