Ebola: Gorillas and other wild animals

Female gorilla in the Jupiter Group
Ngaga Camp,
Republic of Congo, May 2014
Her toddler was clambering in the trees
above her

The conversation at the funeral of a former colleague with another former colleague, a microbiologist with wide interests who I had not seen for some years, turned to the outbreak of ebola virus (EBOV) in West Africa and how it may spread between wild, domesticated and human mammals, and the characteristics needed for one or more reservoir species, in other words, those that carry but do not suffer to the point of rapid mortality the infectious agent.

In May we were at the site of the 2003 outbreak in the Republic of Congo and heard of the devastating effect ebola had on the Western Lowland Gorilla population. Since returning I have had the chance of catching up with the literature on that outbreak and how it was established that ebola has such a devastating effect on the survival of gorillas, with a mortality rate of 90-95% and the estimated loss of 5000 gorillas from a relatively small area.

Magda Bermejo who lives at the camp in the Republic of Congo we visited (see post of 18 August 2014) after the effective loss of her study groups at Lossi to the ebola outbreak, established the death of gorillas and chimpanzees during human outbreaks, found ebola virus in a number of the carcasses and showed an apparent passage from group to group of gorillas rather than independent transmission form a putative reservoir species. But then, and apart from the enormous potential effect on survival of the great apes in Africa, all sorts of question arise as to who or what becomes infected first and how does the infection (not that easily transmitted according to the evidence with contact through body fluids being needed) pass between groups.

Bushmeat has been implicated as the initial source of human infection while bats, particularly, but also duikers, pigs and domestic dogs are suspected as possible reservoir species. Recently, I see those sequencing the virus collected during the current outbreak have found rapid changes and are reaching different conclusions on the origins of EBOV. The article by Gretchen Vogel in Science (29 August 2014) reads:

Some researchers theorized, based on early sequencing data, that EBOV had circulated for decades, undetected, in animals in the region. But the new analysis, strengthened by the unprecedented number of genomes, supports another theory: that the virus spread, via animal hosts, from Central Africa within the last decade. Researchers aren’t sure which animal to blame, but fruit bats are their leading suspects (Science, 11 April, p. 140). At least one fruit bat species known to carry ebolavirus has a population range that stretches from Central Africa across to Guinea.

That more research on ebola and much more money to fund that research are necessary are truisms. The dangers to those working in a human outbreak to collect samples in areas where facilities for the safe care of patients and basic hygiene are poor also cannot be overestimated. Five of those who collected samples for sequencing  in the current human outbreak have died. Until really hard evidence is obtained from extensive surveys in wild (and domestic) animals over meaningful periods of time and over a wide geographical area, speculation and soft epidemiological evidence may have to suffice in the meantime. But, in that meantime and beyond, alongside local outbreaks that devastate human populations, the great apes of Africa are at risk.

Tom, our former colleague, would I am sure have been delighted that his funeral was the occasion for several coffee-room type discussions on science and science politics; Scottish politicians were not rated highly in the latter.

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Useful starting points for further reading:

Bermejo M et al. Ebola outbreak killed 5000 gorillas. Science 314, 1564
Vogel G. 2014. Are Bats Spreading Ebola Across Sub-Saharan Africa? Science 344, 140
Vogel G. 2014. Genomes reveal start of ebola outbreak. Science 345, 989-990
Walsh PD et al. 2003. Catastrophic ape decline in western equatorial Africa. Nature 422, 611-614
Wittmann TJ et al. 2007. Isolates of Zaire ebolavirus from wild apes reveal genetic lineage and recombinants. Proceedings of the National Academy of Sciences of the USA 104, 17123-17127

A Visit to Gorillas in the Congo

One of my earliest memories is of the first non-domestic animal I saw—a gorilla, ’Alfred’ at Bristol Zoo in summer 1946. The snapshot in my brain has the zoo entrance to the left and Alfred’s cage in front of me. My great (grand in genealogical terminology) uncle and aunt and my grandparents are to my left and my parent are to my right. Alfred is dragging a piece of sacking from left to right.

Alfred was an animal celebrity and a source of great pride in Bristol where he lived from 1930 until he died in 1948.

Another gorilla but this time a dead one also made a strong impression on a little boy.‘George’ (I cannot remember his ever been called this in the 1950s) was in the natural history museum at Wollaton Hall. Mounted impressively, upright, hanging on a tree, with his teeth bared and reproductive organs in full view (small remember in the gorilla) he towered above the visitors and this small boy can remember being more than a little scared every time I was taken to see him (probably two or three times a year). George is still there but Wollaton Hall as a natural history museum is a shadow of its former self and confirms my belief that museum display professionals must learn to leave things alone. This gorilla, I read now, was bought by Nottingham Corporation from the 1878 Paris Exposition held to mark the recovery of France from the Franco-Prussian War.

The next time I saw Alfred he was stuffed and on display in the Bristol’s museum, still the cause of great civic pride as recounted by Hannah Paddon in Sam Alberti’s The Afterlives of Animals. That was in 1957. Bristol Zoo went on to have other gorillas in the 1950s and I took photographs of the new accommodation when I went to my last visit to Bristol Zoo in 1963.

Bristol Zoo Gorilla House, 1963

As I wrote in my post of 16 June, the privilege of being able to visit groups of Western Lowland Gorillas and observe the other mammals, birds, reptiles and amphibians in the Congo Basin is an experience of a lifetime. In the middle of May we were with a group of ten clients of Naturetrek in the camps in the Republic of Congo run by Wilderness Safaris, Ngaga and Lango, 340 miles from Brazzaville, both in or adjacent to the Odzala-Kokoua National Park.

At Ngaga we divided into parties of two or four and visited two groups of gorillas, each headed by a silverback, ‘Jupiter’ and ‘Neptune’. These gorillas were habituated by Dr Magda Bermejo and her colleagues. Because of the effects of outbreaks of ebola on the population, the IUCN classification of the Western Lowland Gorilla is 'critically endangered’.

Filming was difficult through the thick vegetation. The camera was often at arms length and liable to shake. However, the footage below also shows the dense Marantaceae foliage, a major source of food for the gorillas, the environment in which they live and the sweat bees they have to put up with. What the video does not show is a female gorilla moving behind us and coming closer to see what we were about. She had a good look from a few yards away and then moved on to join the rest of the group as they climbed into the tops of the trees.

I shall never forget the sight of Neptune climbing the tree with consummate ease—and even striking the pose of the long-dead George. But the large tooth display was the result of a languid yawn as he paused before climbing even higher.

There is no greater privilege in the world than seeing a group of lowland gorillas in the wild in the Congo—sixty-eight years after seeing that unfortunate but great ambassador for gorillas, Alfred.