Gorilla Journal 26, June 2003
Haemorrhagic Fever Caused by the Ebola Virus
The haemorrhagic fever (resulting in bleeding) caused by the Ebola virus
aroused worldwide attention for the first time when it broke out in the
Central African country of Zaire in 1976 (Zaire was renamed the Democratic
Republic of the Congo in 1997). It is caused by a type of virus known
as a filovirus. The disease is transmitted via body fluids of infected
individuals and is fatal in roughly 50-90% of sufferers. So far, it is
known only in Africa. The latest serious epidemic broke out in October
2000 near the northern Ugandan city of Gulu (43,000 inhabitants), claiming
169 deaths. Another epidemic was reported from the Congo Republic in February
2003; at the same time, a huge number of gorillas and chimpanzees died
in this region. A specific therapy or vaccination against the disease
has not yet been found.
Epidemics of Ebola
Named after the Ebola River in the Democratic Republic of the Congo, this
highly infectious disease for the first time provoked media excitement
in 1976. It was not possible at that time to heal or help the people suffering
from Ebola. So far, seven serious outbreaks of the epidemic have been
registered: in 1976 in Sudan and Zaire, in 1977/78 again in Zaire, in
1979 and 1983 in Sudan, in 1995 in the Zairean city of Kikwit, and in
October 2000 in Uganda. The latest epidemic occurred in the villages of
Kéllé and Mbomo, about 800 km north of Brazzaville, in February
2003. According to a WHO announcement dated 6 May, 128 individuals died
out of 143 infected a mortality rate of 90%.
Even today, the mechanisms of transmission of the disease are not completely
understood, and there may be both reservoir species (the host carries
the virus without suffering from the disease) and vector species (the
host transfers the virus to animals that subsequently suffer from the
disease) that have not been identified. This means that humans living
in the deep forests in eastern, Central and western Africa or consuming
animal meat from these regions (bushmeat) run an extremely high risk of
infection. It is very likely that the disease is transmitted to humans
through contact with apes, especially chimpanzees and gorillas, which
are killed for meat by the local population.
Course of the Disease
A first indication is provided by the clinical picture of those infected
and by a molecular-genetic test for the virus (PCR), later also by a test
for special antibodies. Haemorrhagic virus infections with high mortality
rates like Ebola still cannot be treated successfully. Infected persons
need to be isolated.
The symptoms usually appear after 2 to 21 days following the infection:
fever, shivering fits, headache, muscle pain and loss of appetite. They
are followed by vomiting, diarrhoea, and stomach and intestinal cramps,
as well as severe pain in the upper chest. The disease provokes serious
coagulation problems and the patients start bleeding everywhere. They
bleed in the gastro-intestinal tract, from the skin and mucous membranes
as well as from the puncture marks of hypodermic syringes and infusions,
but also from vital internal organs (liver, spleen, lungs and kidneys).
Between day 5 and 7 after the infection they develop a skin rash similar
to measles, but which is visible only on light skin. Very often there
are neurologic symptoms with paralysis and disturbances of the patients’
mental constitution. In most cases people die after 10 days from multi-organ
failure.
Transmission
The disease is transmitted when contact is made with body fluids of infected
individuals. Hospital workers who had contact with patients treated with
infected syringes or surgical instruments, or family members nursing the
patients, have commonly been infected with the virus.
Like the HI-Virus, Ebola can also be transmitted through sexual contact.
Due to close contact, many people catch the virus while preparing the
highly infectious bodies for burial. Airborne infection via the respiratory
tract is not considered likely. Patients who have already suffered from
Ebola are immune to subsequent infection and are off the danger list.
Outlook and Prognosis
A major problem is that the primary focus of infection of the Ebola virus
is still unknown. A number of efforts are currently underway to identify
it. During the last epidemics many animals in the affected regions have
been captured and examined to find out whether they are a primary host
and carry the virus. Without direct proof of the natural or primary host
many questions remain unanswered: ”Can the Ebola virus survive in
different hosts?” or ”Is it possible that the virus needs no
specific host at all and can nevertheless survive in the African rainforest?”
There are indications, though, that humans were infected by the consumption
of ape meat. Nevertheless, apes cannot be considered as the reservoir
host because they also die of the disease.
So far, no vaccination is available, but a number of research centres
are working on the development of a vaccine.
Christoph Lübbert
Dr. Christoph Lübbert specializes in
internal medicine in a hospital in Leipzig. In 1991, he travelled to eastern
Africa for the first time, and after that he visited Africa many times.
In 1996, he published a travel guide for Uganda and eastern Congo.
Conservation
areas
Homepage |