Infectious diseases in the Green Heart of Africa

Watertight clothes, equipped with air filtration equipment, used for high-risk wild animal necropsy. Odzala National Park Republic of Congo, June 2003.
© Pierre Rouquet (used with kind permission)

Invisible killers in the Congo Basin rainforests

Infectious diseases claim millions of victims every year across the African continent. In their wake, they leave not only incapacitated people and devastated families, but also decimated wildlife populations and vulnerable forests. How can diseases such as AIDS, ebola and malaria inflict such damage?1


Ebola hemorrhagic fever is a severe, often-fatal disease that affects humans and non-human primates, such as monkeys, gorillas and chimpanzees.2 This disease is one of the most virulent viral killers known to humankind, causing death in 50%-90% of all clinically ill patients. No effective medical treatment or vaccine exists for ebola virus infection.

Home of a killer
The natural reservoir of the ebola virus seems to be in the rainforests of Africa, but has not yet been identified precisely. The disease has been confirmed in 6 African countries: the Democratic Republic of Congo, Congo-Brazzaville, Gabon, Sudan, Cote D’Ivoire and Uganda.3

How ebola spreads
It is suspected that the disease is spread through the butchering and handling of primate bushmeat. In the Congo River Basin, most of the recent outbreaks of ebola in humans have been closely associated with large die-offs of great apes that are also susceptible to the disease.

The impact of ebola on great apes
In the areas affected by ebola, two great apes exist: the western lowland gorilla (Gorilla gorilla gorilla) and the central chimpanzee (Pan troglodytes troglodytes).

In the Minkébé Forest in northern Gabon, it is suspected that the virus has killed more than 90% of the western lowland gorilla and central chimpanzee.

Great apes need time to recover from population declines because they are slow to reproduce compared with many other mammals. For example, on average a female chimpanzee will only breed after 13 years of age, will give birth to only 4 or 5 offspring during her life (with around 6 years between births), and 40% of chimpanzee die before reaching maturity.

Therefore, if ebola reduces populations by up to 90%, any additional pressure from hunting may push them to extinction.

What is WWF doing about this problem?


HIV/AIDS is causing a severe crisis in sub-Saharan Africa, the worst affected region in the world. Across the continent, approximately 28.5 million people are living with the disease. HIV/AIDS accounted for 2.2 million deaths in 2001 and this heavy toll is rising constantly.

The legacy of AIDS/HIV in Africa
HIV/AIDS is now the leading cause of death in the continent, accounting for almost 1 in 4 of all deaths. The disease is putting a serious strain on Africa’s efforts to alleviate the poverty of its people, especially since the disease is disproportionately affecting the better-trained young professionals in urban environments that are indispensable for development.

Central Africa, so far relatively spared
Central Africa is not the worst affected region in the continent. In the region, prevalence rates are under 10% in most countries, compared to over 20% in all southern African countries. However, there has been a sharp increase in some countries in the region, notably in Cameroon, hinting to a possibility of an explosion of the epidemic in the region.

How logging could contribute to the problem
There is a concern that opening up previously isolated regions in the forest by logging companies will result in increased prevalence of the disease in these regions. The spread of HIV/AIDS in the forests of the Congo River Basin could become another undesired side effect of the increased exploitation of the forest, similar to the bushmeat problem.

Moreover, there is growing evidence that HIV transmission, as well as the transmission of other deadly viral diseases like ebola, are directly related to the killing and consumption of apes and primates.

What is WWF doing about this problem?

1 CARPE. 2005. The Forests of the Congo River Basin: A preliminary assessment. Balmar, Washington DC.
2 Holmes-Maybank, K. 2004. An Overview of Ebola. South Carolina Journal of molecular medicine (SCJMM), 1:15-21.
3 GRASP. 2004. Scientists Fear Ebola May Be Responsible for Sudden Gorilla Disappearance. Press Release.

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