Ebola mutagenicity; Contingency planning

[Doug Cutrell]

The following points have been of recent concern to me, as someone
with a molecular biology background and a course in virology as a
graduate student at MIT:

1) Ebola Zaire has never before been present in a large urban
population.  All previous outbreaks have been confined to small
populations.

2) Ebola Zaire and Ebola Reston are very similar.  There is some
evidence that Ebola Reston may be airborne.

3) Ebola is an RNA virus with a small non-segmented genome.  Viruses
of this type have high mutation rates due to a) the lack of error
correction during RNA synthesis and b) the possibility of
recombination events.  Influenza virus is an example of a virus with
these characteristics.

3) The combination of the above three points suggests that if Ebola
Zaire ever emerges in an outbreak of significant size in a densely
populated urban environment, the evolution of an airborne variety may
be a rapid event.  Specifically, the argument is that a) this would
provide evolutionary pressure for an airborne variety b) there is a
closely related viral species which may be airborne and c) the virus
has an intrinsically high potential for mutation.

4) Compounding the above scenario are indications that Ebola may be
capable of entering rodent populations, from which it could spread via
fleabites.  It does appear to be extremely contagious via any possible
blood-borne means.  This could make an urban outbreak very difficult
to completely quash... and a chronic, sub-epidemic Ebola presence in
an urban environment would provide exactly the evolutionary pressures
most likely to evolve an airborne variety.

The above points do not make the case that the evolution of an
airborne strain of Ebola Zaire is probable.  However, they do suggest
that the possibility is significant.  Indeed, even a probability of 5%
of such an event occurring should lead to serious consideration of
contingency plans for its occurrence, given the potential
consequences.

___________________________________________________________________
Doug Cutrell                    General Partner
doug at OpenMind.com               Open Mind, Santa Cruz
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