The Worlds Fight Against Microbes


Many infectious diseases that were nearly eradicated from the
industrialized world, and newly emerging diseases are now breaking out all over
the world due to the misuse of medicines, such as antibiotics and antivirals,
the destruction of our environment, and shortsighted political action and/or
inaction.
Viral hemorrhagic fevers are a group of diseases caused by viruses from
four distinct families of viruses: filoviruses, arenaviruses, flaviviruses, and
bunyaviruses. The usual hosts for most of these viruses are rodents or
arthropods, and in some viruses, such as the Ebola virus, the natural host is
not known. All forms of viral hemorrhagic fever begin with fever and muscle
aches, and depending on the particular virus, the disease can progress until the
patient becomes deathly ill with respiratory problems, severe bleeding, kidney
problems, and shock. The severity of these diseases can range from a mild
illness to death (CDC I).
The Ebola virus is a member of a family of RNA (ribonucleic acid)
viruses known as filoviruses. When these viruses are magnified several thousand
times by an electron microscope they have the appearance of long filaments or
threads. Filoviruses can cause hemorrhagic fever in humans and animals, and
because of this they are extremely hazardous. Laboratory studies of these
viruses must be carried out in special maximum containment facilities, such as
the Centers for Disease Control (CDC) in Atlanta, Georgia and the United States
Army Medical Research Institute of Infectious Diseases (USAMRIID), at Fort
Detrick in Frederick, Maryland (CDC I,II).
The Ebola hemorrhagic fever in humans is a severe, systemic illness
caused by infection with Ebola virus. There are four subtypes of Ebola virus
(Ebola-Zaire, Ebola-Sudan, Ebola-Ivory Coast, and Ebola-Reston), which are not
just variations of a single virus, but four distinct viruses. Three of these
subtypes are known to cause disease in humans, and they are the Zaire, Sudan,
and Ivory Coast subtypes. Out of all the different viral hemorrhagic fevers
known to occur in humans , those caused by filoviruses have been associated with
the highest case-fatality rates. These rates can be as high as 90 percent for
epidemics of hemorrhagic fever caused by Ebola-Zaire virus. No vaccine exists to
protect from filovirus infection, and no specific treatment is available (CDC
II).
The symptoms of Ebola hemorrhagic fever begin within 4 to 16 days after
infection. The patient develops chills, fever, headaches, muscle aches, and a
loss of appetite. As the disease progresses vomiting, diarrhea, abdominal pain,
sore throat, and chest pain can occur. The blood fails to clot and patients may
bleed from injection sites as well as into the gastrointestinal tract, skin, and
internal organs (CDC I).
The Ebola virus is spread through close personal contact with a person
who is very ill with the disease, such as hospital care workers and family
members. Transmisson of the virus can also occur from the reuse of hypodermic
needles in the treatment of patients. This practice is common in developing
countries where the health care system is underfinanced (CDC I).
Until recently, only three outbreaks of Ebola among people had been
reported. The first two outbreaks occurred in 1976. One was in western Sudan,
and the other in Zaire. These outbreaks were very large and resulted in more
than 550 total cases and 340 deaths. The third outbreak occurred in Sudan in
1979. It was smaller with only 34 cases and 22 deaths. Three additional
outbreaks were identified and reported between 1994 and 1996: a large outbreak
in Kikwit, Zaire with 316 cases and 244 deaths; and two smaller outbreaks in the
Ivory Coast and Gabon. Each one of these outbreaks occurred under the
challenging conditions of the developing world. These conditions including a
lack of adequate medical supplies and the frequent reuse of needles, played a
major part in the spread of the disease. The outbreaks were controlled quickly
when appropriate medical supplies were made available and quarantine procedures
were used (CDC I).
Ebola-Reston, the fourth subtype, was discovered in 1989. The virus was
found in monkeys imported from the Philippines to a quarantine facility in
Reston, Virginia which is only about ten miles west of Washington, D.C.
(Preston 109). The virus was also later detected in monkeys imported from the
Philippines into the United States in 1990 and 1996, and in Italy in 1992.
Infection caused by this subtype can be fatal in monkeys; however, the only four
Ebola-Reston virus infections confirmed in humans did not result in the disease.
These four documented human infections resulted in no clinical illness.
Therefore, the Ebola-Reston subtype appears less capable of causing disease in
humans than the other three subtypes. Due to a lack of research of the Ebola-
Reston