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59
Figure 16:
Ebola epidemic outbreaks across the Congo Basin
are a significant threat to gorillas, and also impact the few re-
maining populations less exposed to poaching and habitat loss.
Figure 17:
Ebola is a major threat particularly to the gorillas,
with severe casualties following outbreaks. As these come in ad-
dition to deaths from poachers and habitat loss, the outbreaks
can become detrimental.
EBOLA, A MAJOR THREAT TO GREAT APES
Awareness that health and biodiversity conservation are linked
is increasing, in the case of great ape conservation, disease
threats have moved to center stage. Ebola hemorrhagic fever
(EHF) is thought be a major driver in gorilla and chimpanzee
population declines in Africa, rivaling hunting and habitat loss
as a major threat to their survival. The health crisis facing these
endangered species underlies the need to understand more
about this disease, how it affects apes and what can be done to
fight the disease.
HF is caused by the Ebolavirus (EBOV), a negative-strand RNA
virus of the Family Filoviridae. Although there are five recog-
nized species of EBOV, only two have been implicated in great
ape deaths; Zaire ebolavirus (ZEBOV) in the Democratic Re-
public of Congo, the Republic of Congo and Gabon and Ivory
Coast ebolavirus (CIEBOV) in the Ivory Coast. Precise mortality
rates in great apes are missing but, based on field observations
may reach 90% (Formenty
et al.
, 1998; Walsh
et al.
, 2003; Cail-
laud
et al.
, 2006; Bermejo
et al.
, 2006) EBOV is transmitted
through direct contact with body fluids of infected animals or
persons (Jaax
et al.
, 1995; Leroy
et al.
, 2004; Pourrut
et al.
, 2005).
Gorilla
Unspecified
mammals
Antilopes
Chimpanzee
Mandrills
Unspecified
monkeys
Ebola wildlife animal victims
Percentage on a sample of 500 individuals reported
in Gabon and Congo
Source: Caillaud, D., et al., 2006;Lahm, S., A., 2006.
Survival probability in Odzala-Kokoua
National Park
Cumulative survival
Ebola
outbreak
Note: the cumulative
survival is the probability
that a gorilla is found alive
at the dates indicated in
the chart
10
20
30
40
50
60
70
80
0
0,2
2002
2003
2004
2005
0,4
0,6
0,8
1,0
0
Solitary males
Group living individuals