Mythbusting is a worthy goal for any forum or news publication, and with
the release of the new, long term publicly accessible study the FALSE
MYTH that the rate of Lyme Disease is connected to the number of deer
will hopefully be eliminated once and for all since this 13 year, very
comprehensive study found the same thing as earlier investigations: the
critical factors are the numbers of ground nesting rodents which serve as
reservoirs for Lyme Disease, and those rodents' food supplies. The deer
simply are food sources for the same later stages of ticks as we people
are. (In fact, in some studies of flea borne diseases killing off the
alternative hosts for disease bearing fleas at the stages where they
could feed on humans actually increased the number of those parasites on
humans since they preferred animal food source was not available, so
perhaps the same may happen with ticks.)
This most recently completed study is titled:
"Climate, Deer, Rodents, and Acorns as Determinants of Variation in
Lyme-Disease Risk"and the authors who are from Bard College and the
Institute of Ecosystem Studies are Doctors Richard S. Ostfeld, Charles
D. Canham, Kelly Oggenfuss, Raymond J. Winchcombe, Felicia Keesing.
The study abstract states:
"Risk of human exposure to vector-borne zoonotic pathogens is a
function of the abundance and infection prevalence of vectors. We
assessed the determinants of Lyme-disease risk (density and Borrelia
burgdorferi-infection prevalence of nymphal Ixodes scapularis ticks)
over 13 y on several field plots within eastern deciduous forests in
the epicenter of US Lyme disease (Dutchess County, New York). We used
a model comparison approach to simultaneously test the importance of
ambient growing-season temperature, precipitation, two indices of deer
(Odocoileus virginianus) abundance, and densities of white- footed mice
(Peromyscus leucopus), eastern chipmunks (Tamias striatus), and acorns
(Quercus spp.), in both simple and multiple regression models, in
predicting entomological risk." It goes on to say, "Indices of deer
abundance had no predictive power, and precipitation in the current year
and temperature in the prior year had only weak effects on entomological
risk."
Notice that the factors which did matter were the numbers of the studied
ground-nesting rodents and the foods they ate and collected for their
winter sustenance: "The strongest predictors of a current year's risk
were the prior year's abundance of mice and chipmunks and abundance of
acorns 2 y previously."
Lest an impact on those rodents or the acorns by deer be suggested, they
continue, "In no case did inclusion of deer or climate variables improve
the predictive power of models based on rodents, acorns, or both. We
conclude that interannual variation in entomological risk of exposure to
Lyme disease is correlated positively with prior abundance of key hosts
for the immature stages of the tick vector and with critical food
resources for those hosts."
The pdf of the study which is in Volume 4, Issue 6, June 2006 of the
Public Library of Science, PLOS Biology, open access, peer-reviewed
science journal may be read at
http://biology.plosjournals.org/archive/1545-7885/4/6/pdf/
10.1371_journal.pbio.0040145-p-S.pdf
and the full text article can be found at
<http://biology.plosjournals.org/perlserv/?request=get-document
&doi=10.1371/journal.pbio.0040145>
Should the internet URLs change after the early announcement today, the
volume and issue number, as well as the article title can be used by a
reader or librarian to find the current locations.
-- Sukie (not a vet, and not speaking for any of the below in my
private posts)
Recommended health resources to help ferrets and the people who love
them:
Ferret Health List
http://www.smartgroups.com/groups/ferrethealth
FHL Archives
http://ferrethealth.org/archive/
AFIP Ferret Pathology
http://www.afip.org/ferrets/index.html
Miamiferrets
http://www.miamiferret.org/fhc/
International Ferret Congress Critical References
http://www.ferretcongress.org
[Posted in FML issue 5238]
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