posted on Aug, 5 2003 @ 05:50 PM
I feel the need to do some loooong posts on infectious diseases not normally native to the west, today i shall start with the ebola HF virus.
Ebola hemorrhagic fever (Ebola HF) is a severe, often-fatal disease in humans and other primates (monkeys, gorillas, and chimps) that has appeared
sporadically in africa since its initial recognition in 1976.
The disease is caused by infection with Ebola virus, named after a river in the Democratic Republic of the Congo (formerly Zaire) in Africa, where it
was first recognized. The virus is one of two members of a family of RNA viruses called the Filoviridae. There are four identified subtypes of Ebola
virus. Three of the four have caused disease in humans: Ebola-Zaire, Ebola-Sudan, and Ebola-Ivory Coast. The fourth, Ebola-Reston, has caused disease
in nonhuman primates, but not in humans
So where do we find its natural habitat?
The exact origin, locations, and natural habitat (known as the "natural reservoir") of Ebola virus remain unknown. However, on the basis of
available evidence and the nature of similar viruses, researchers believe that the virus is zoonotic (animal-borne) and is normally maintained in an
animal host that is native to the African continent. A similar host is probably associated with Ebola-Reston which was isolated from infected
cynomolgous monkeys that were imported to the United States and Italy from the Philippines. The virus is not known to be native to other continents,
such as North America.
Where do cases of Ebola normally occur?
Confirmed cases of Ebola HF have been reported in the Democratic Republic of the Congo, Gabon, Sudan, the Ivory Coast, Uganda, and the Republic of the
Congo. An individual with serologic evidence of infection but showing no apparent illness has been reported in Liberia, and a laboratory worker in
England became ill as a result of an accidental needle-stick. No case of the disease in humans has ever been reported in the United States. Ebola-
Reston virus caused severe illness and death in monkeys imported to research facilities in the United States and Italy from the Philippines; during
these outbreaks, several research workers became infected with the virus, but did not become ill.
Ebola HF typically appears in sporadic outbreaks, usually spread within a health-care setting (a situation known as amplification). It is likely that
sporadic, isolated cases occur as well, but go unrecognized. A table showing a chronological list of known cases and outbreaks is available.
How is Ebola spread?
Infections with Ebola virus are acute. There is no carrier state. Because the natural reservoir of the virus is unknown, the manner in which the virus
first appears in a human at the start of an outbreak has not been determined. However, researchers have hypothesized that the first patient becomes
infected through contact with an infected animal.
After the first case-patient in an outbreak setting is infected, the virus can be transmitted in several ways. People can be exposed to Ebola virus
from direct contact with the blood and/or secretions of an infected person. Thus, the virus is often spread through families and friends because they
come in close contact with such secretions when caring for infected persons. People can also be exposed to Ebola virus through contact with objects,
such as needles, that have been contaminated with infected secretions.
Nosocomial transmission refers to the spread of a disease within a health- care setting, such as a clinic or hospital. It occurs frequently during
Ebola HF outbreaks. It includes both types of transmission described above. In African health-care facilities, patients are often cared for without
the use of a mask, gown, or gloves. Exposure to the virus has occurred when health care workers treated individuals with Ebola HF without wearing
these types of protective clothing. In addition, when needles or syringes are used, they may not be of the disposable type, or may not have been
sterilized, but only rinsed before reinsertion into multi-use vials of medicine. If needles or syringes become contaminated with virus and are then
reused, numerous people can become infected.
Ebola-Reston appeared in a primate research facility in Virginia, where it may have been transmitted from monkey to monkey through the air. While all
Ebola virus species have displayed the ability to be spread through airborne particles (aerosols) under research conditions, this type of spread has
not been documented among humans in a real-world setting, such as a hospital or household.
What are the symptoms of Ebola hemorrhagic fever?
The incubation period for Ebola HF ranges from 2 to 21 days. The onset of illness is abrupt and is characterized by fever, headache, joint and muscle
aches, sore throat, and weakness, followed by diarrhea, vomiting, and stomach pain. A rash, red eyes, hiccups and internal and external bleeding may
be seen in some patients.
Researchers do not understand why some people are able to recover from Ebola HF and others are not. However, it is known that patients who die usually
have not developed a significant immune response to the virus at the time of death.
How is Ebola hemorrhagic fever treated?
There is no standard treatment for Ebola HF. Patients receive supportive therapy. This consists of balancing the patientís fluids and electrolytes,
maintaining their oxygen status and blood pressure, and treating them for any complicating infections.
What challenges remain for the control and prevention of Ebola hemorrhagic fever?
Scientists and researchers are faced with the challenges of developing additional diagnostic tools to assist in early diagnosis of Ebola HF and
conducting ecological investigations of Ebola virus and its possible reservoir. In addition, one of the research goals is to monitor suspected areas
to determine the incidence of the disease. More extensive knowledge of the natural reservoir of Ebola virus and how the virus is spread must be
acquired to prevent future outbreaks effectively.