1) Relation shown between insecticide resistance & disease transmission
(Nature)
2) WNV Treatment with antiviral agent successful in labs (NYT article)
~~~~~~~~~~
1) "INSECTICIDES AND MOSQUITO-BORNE DISEASE" appears as a brief
communication in this week's (October 26, 2000) issue of Nature (McCarroll
et al. 407:961 - 962).
Abstract: The primary means of controlling mosquito-borne diseases such as
malaria and filariasis is still by residual spraying with insecticides.
Here we show that insecticide-resistant Culex quinquefasciatus mosquitoes
are less likely to transmit filariasis than their insecticide-susceptible
counterparts. If this surprising finding extends to other combinations of
insect species, insecticide-resistance mechanisms and disease, it could
have widespread consequences for the control of vector-borne disease.
More: The study found that mosquitoes (Culex quinquefasciatus) which are
resistant to the insecticide fenthion express a certain esterase enzyme at
high levels in several tissues including the gut. The authors use
quantitative PCR (Polymerase Chain Reaction) to demonstrate a strong
negative correlation between the amount of Wuchereria bancrofti DNA found
in the mosquito and the esterase level. The results convincingly show that
fenthion-resistant Culex quinquefasciatus have lower densities of W.
bancrofti as compared to fenthion-susceptible mosquitoes. Wuchereria
bancrofti is one of the filarial nematode parasites transmitted to humans
by mosquitoes. (Summary drawn from comments of ProMED moderator EP, Oct 30,
2000, and Herms Medical Entomology, 1969).
2) IN THE LAB: A GLIMMER OF HOPE IN TREATING WEST NILE VIRUS
By JOHN O'NEIL. New York Times, October 31, 2000
Ribavirin, an antiviral agent used to treat hepatitis C, was effective
against West Nile virus in laboratory experiments, an article in the
October issue of The Journal of Infectious Diseases reported.
The chief author of the study, Dr. Ian Lipkin of the University of
California at Irvine, tested 10 antiviral agents at high doses for their
ability to protect human brain cells in test tubes. Ribavirin slowed the
virus's spread and protected the cells against damage, he said, as did one
other compound, pyrazofurin, which, unlike ribavirin, is too toxic at those
levels for use in humans.
Preliminary results of the study were made public last summer.
Since no treatment is available for West Nile ÷ the few patients who areÊ
seriously affected are usually hospitalized to manage complications ÷ Dr.
Lipkin said in an interview that he expected that some doctors wouldÊ
prescribe ribavirin for patients doing poorly.
Doctors in Israel, where the death toll from West Nile reached 30 for the
year, have been doing so, he said, but orally and in small doses, and
without success. Dr. Lipkin said that the levels used in his experiment
were the equivalent of a far higher dose, delivered intravenously.
He recommended that doctors considering giving ribavirin to contact the
federal Centers for Disease Control and Prevention so the treatment can
take place in the context of the clinical trials.
"This is not going to be an ideal drug," he said in an interview, "but it's
available and could be useful in the short term."
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lois Levitan, PhD Program Leader
Environmental Risk Analysis Program
Center for the Environment
213 Rice Hall, Cornell University
Ithaca, New York USA 14853
Phone: (607) 255-4765 Fax: (607) 255-0238
Email: LCL3@cornell.edu
Program Email: envrisk@cornell.edu
http://www.cfe.cornell.edu/risk
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Received on Tue Oct 31 12:39:26 2000
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