My Candidate for the Ebola Reservoir Organism (was Re: Chimpanzee Ebola outbreak)

Doug Yanega dyanega at
Sun May 28 12:06:37 EST 1995

In article <Pine.SOL.3.91.950527223520.12380B-100000 at corona>, Patrick
O'Neil <patrick at corona> wrote:

> > : > The newest issue of science (19 May 1995, Vol 268, Pgs974-975) has a
> > : short article on an outbreak of ebola in chimpanzees that occurred last
> > : November. This is the one on the Ivory Coast's tai Forest. Also, this is
> [...]
> > 
> > : I'm staggered to see how, for something so prominent as Ebola, the "left
> > : hand doesn't know what the right is doing" - all the evidence suggests
> > : that the reservoir of the virus is something the chimpanzees eat,
> > : something people who eat monkeys eat, and (logically) is probably a
> > : mammal, most likely a primate. There have, however, been several
> > : recently-published studies on the diet of wild chimps, and their main prey
> > : are *Red Colobus monkeys*. How come with all the high-profile activity, no
> This could well turn out to be true but other human cases have had 
> (apparently) nothing to do with monkeys or chimps.  In any case, though 
> Red Colobus monkeys are a major prey of chimps, it is still not the only 
> prey.  Chimps have been known to bring down small deer and related 
> animals too.  Considering the rarity of Ebola infections, I would also 
> tend to think that it might be linked, following your logic, to a 
> relatively rare prey of the chimps.  They occassionally kill prey X and 
> prey X is sometimes infected with Ebola.

I don't question that there are a few points not entirely explained by the
hypothesis. My point was that there are certainly more things *pointing*
to the Colobus monkeys than any other possibilities, as per the list
above. The Science article specified that there have been many cases among
people who eat monkeys, and I've seen other articles specifically
proposing that there must be "some as-yet unidentified primate serving as
reservoir" - but which then go on to essentially propose that the virus
"must be transferred by insect vectors," because they saw that as the only
way for chimps to be affected. This clearly suggests to me that those
authors were unaware that chimps ate other primates. Colobus are not the
main item in the chimps' *diet*, which is largely vegetarian, but when
they *do* catch prey, it is mostly Colobus monkeys. This could indeed be a
relatively rare occurrence, for chimps to catch a Colobus that happens to
harbor the virus. Yes, conceivably it could be bush pigs or deer, but I
was following the suggestion by others that a *primate* reservoir was the
most likely scenario. 
   Given all the logical reasons to suspect Colobus monkeys, then, why has
no one ever suggested that they should be a primary target, especially
those folks *investigating* the disease? It would seem to be a sorry
excuse for detective work if an entomologist (which is what I happen to
be) can come up with a better lead by reading semi-popular literature
(Natural History, Science, and Nature) than the folks who are presently
directly responsible for solving the problem. I was posting here
essentially in hope of provoking either (a) someone who can indicate to me
that this is NOT a new hypothesis (the most likely event, we can only
hope!) or (b) someone well-versed enough and intimately placed enough to
recognize this *is* something that's been overlooked and act on it.
Doug Yanega
Illinois Natural History Survey, Center for Biodiversity
607 E. Peabody Dr. Champaign, IL 61820  USA
"There are some enterprises in which a careful disorderliness is
    the true method" - Herman Melville, Moby Dick

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