The Last Stand of the Gorilla

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).

Survival probability in Odzala-Kokoua National Park Cumulative survival

1,0

0,8

0,6

Solitary males Group living individuals

0,4

0,2

Note: the cumulative survival is the probability that a gorilla is found alive at the dates indicated in the chart

Ebola outbreak

0

2003

2004

2005

2002

Ebola wildlife animal victims Percentage on a sample of 500 individuals reported in Gabon and Congo

80

70

Unspecified monkeys

60

50

Mandrills

40

Chimpanzee

30

 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.

20

Gorilla

Unspecified mammals Antilopes

10

0

Source: Caillaud, D., et al., 2006;Lahm, S., A., 2006.

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