<x-charset utf-7>Another factor to consider in original outbreaks and incidence the following
year in endemic areas is weather. The original NY outbreak followed a
period of drough then extremely heavy rain. Similar situation in Texas
right now. Don't know if +ACI-drought+ACI- (probably a relative term) was a
situation in Fla and LA or not but antecedant heavy rainfall was. Mosquitos
will postpone egg laying during dry periods, allowing higher numbers of
infected females to build up, which then lay their eggs en masse. The
relative paucity of activity in the NE this year may also be related in part
at least to the extremely dry weather.
Agree that more needs to be done in tracking the effectiveness of spraying.
Suspect that is a factor in places like NY, NJ and Fla, where coordinated
spraying efforts, even preventative spraying based on mosquito/bird
surveillance (rather than waiting for human cases) has been employed in many
areas.
Also agree we need much more species specific information on viremia in
birds. The spread of the virus to date does not appear to be consistent
with migratory birds being the major factor in my opinion. It is more a
contiguous pattern, radiating out from the epicenter in NY to adjoining
counties and states (and Canada), North, South and West.
If it is only, or predominantly, nonmigratory species which are also killed
rapidly that develop sufficient viremia to keep the cycle going, it would
indeed tend to die out rapidly in areas that are particularly active.
Eleanor Kellon, V.M.D.
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Received on Mon Aug 05 15:09:26 2002
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