EBOLA HAEMORRHAGIC FEVER
haemorrhagic fever (EHF) is one of the most virulent viral diseases
known to humankind, causing death in 50-90% of all clinically ill cases.
The disease has its origins in the jungles of Africa and Asia. Several
different forms of Ebola virus have been identified and may be associated
with other clinical expressions, on which further research is required.
- The Ebola virus is transmitted by direct contact
with the blood, secretions, organs or semen of infected persons. Transmission
through semen may occur up to seven weeks after clinical recovery,
as with Marburg haemorrhagic fever.
- Transmission of the Ebola virus has also occurred
by handling ill or dead infected chimpanzees, as was documented in
Côte d'Ivoire and Gabon.
- Health care workers have frequently been infected
while attending patients. In the 1976 epidemic in Zaire, every Ebola
case caused by contaminated syringes and needles died.
2 to 21 days
Symptoms: Ebola is often characterized by the sudden
onset of fever, weakness, muscle pain, headache and sore throat. This
is followed by vomiting, diarrhoea, rash, limited kidney and liver functions,
and both internal and external bleeding.
Commercially unavailable specialized laboratory
tests on blood specimens detect specific antigens and/or genes of the
virus, isolate the virus in cell culture or detect IgM and IgG antibodies.
These tests present an extreme biohazard and are only conducted
under maximum biological containment conditions.
- No specific treatment or vaccine exists for Ebola
- Severe cases require intensive supportive care,
as patients are frequently dehydrated and in need of intravenous fluids.
- Experimental studies involving the use of hyper-immune
sera on animals demonstrated no long-term protection against the disease
after interruption of therapy.
Ebola virus was first identified in a western equatorial province of
Sudan and in a nearby region of Zaire (now Democratic Republic of the
Congo) in 1976 after significant epidemics in Yambuku, northern Zaire,
and Nzara, southern Sudan.
- Between June and November 1976 the Ebola virus
infected 284 people in Sudan, with 117 deaths. In Zaire, there were
318 cases and 280 deaths in September and October. An isolated case
occurred in Zaire in 1977, a second outbreak in Sudan in 1979.
- In 1989 and 1990, a filovirus, named Ebola-Reston,
was isolated in monkeys being held in quarantine in laboratories in
Reston (Virginia), Alice (Texas) and Pennsylvania, United States of
America. In the Philippines, Ebola-Reston infections occurred in the
quarantine area for monkeys intended for exportation, near Manila.
Ebola-related filoviruses were isolated from cynomolgus monkeys (Macacca
fascicularis) imported into the United States of America from
the Philippines in 1989. A number of the monkeys died and at least
four persons were infected, although none of them suffered clinical
- A large epidemic occurred in Kikwit, Zaire in 1995
with 315 cases, 244 of which had fatal outcomes.
- One human case of Ebola haemorrhagic fever and
several cases in chimpanzees were confirmed in Côte d'Ivoire in 1994-95.
- In Gabon, Ebola haemorrhagic fever was first documented
in 1994 and outbreaks occurred in February 1996 and July 1996.
- Ebola virus infections were not reported again
until the autumn of 2000 when an outbreak occurred in northern Uganda.
the most recent outbreak, nearly 1100 cases with over 800 deaths have
been documented since the virus was discovered.
- Suspected cases should be isolated from other patients
and strict barrier nursing techniques practised.
- All hospital personnel should be briefed on the
nature of the disease and its routes of transmission. Particular emphasis
should be placed on ensuring that high-risk procedures such as the
placing of intravenous lines and the handling of blood, secretions,
catheters and suction devices are carried out under barrier nursing
conditions. Hospital staff should have individual gowns, gloves and
masks. Gloves and masks must not be reused unless disinfected.
- Patients who die from the disease should be promptly
buried or cremated.
- As the primary mode of person-to-person transmission
is contact with contaminated blood, secretions or body fluids, any
person who has had close physical contact with patients should be
kept under strict surveillance, i.e. body temperature checks twice
a day, with immediate hospitalization and strict isolation recommended
in case of temperatures above 38.3°C (101°F). Casual contacts should
be placed on alert and asked to report any fever.
- Surveillance of suspected cases should continue
for three weeks after the date of their last contact.
- Hospital personnel who come into close contact
with patients or contaminated materials without barrier nursing attire
must be considered exposed and put under close supervised surveillance.
- The natural reservoir of the Ebola virus seems
to reside in the rain forests of Africa and Asia, but has not yet
been identified. Different hypotheses have been developed to try to
explain the origin of Ebola outbreaks. Initially, rodents were suspected,
as is the case with Lassa fever whose reservoir is a wild rodent (Mastomys).
Another hypothesis is that a plant virus may have caused the infection
of vertebrates. Laboratory observation has shown that bats experimentally
infected with Ebola do not die and this has raised speculation that
these mammals may play a role in maintaining the virus in the tropical
- Although non-human primates have been the source
of infection for humans, they are not thought to be the reservoir.
They, like humans, are infected directly from the natural reservoir
or through a chain of transmission from the natural reservoir.
- Extensive ecological studies are currently under
way in Côte d'Ivoire to identify the reservoir of Ebola. Studies to
identify the reservoir of Marburg virus, a closely related filovirus
are being conducted in the Democratic Republic of the Congo.
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