A Late Mosquito
(This column was first published in the October 28, 2002 issue of The Buffalo News.)
This evening a mosquito invaded my workroom. You can't blame the little critter for making its way inside to escape near-freezing temperatures. It probably thought that my more temperate den might extend its life a few more days.
Sorry little Culexette. My reaction to this invasion was quite different from what it would have been a few years ago. Then I would simply have waved the insect off if it zoomed too close. This time I stalked the tiny buzzard with care until I managed to dispatch it with a loud handclap.
Indeed, there was a bit of fear associated with my reaction. I fall into that "elderly" category that, along with the very young, is threatened by certain West Nile Virus-carrying mosquito species. I cannot tell a Culex pipiens from any other kind of mosquito so, like most of us nowadays, I am not about to take unnecessary chances. I didn't want to be injected with a possibly, even if rarely, fatal disease by one of those flying hypodermics. Since there are no shots for WNV, that slap was my alternative.
In any case, my experience made me wonder just how bad is WNV. How common has it been this year? Will it become more prevalent in the years ahead? Predicting the future is like drawing to an inside straight, but perhaps comparisons can give some insight.
Because the number of identified human cases is so small, I will instead look to birds for they (and horses) appear to be major targets of the disease. Small yes, but as of this writing there have been 3296 human cases reported nationally with 182 deaths; in New York 71 cases and 5 deaths.
But the birds suffered even more. In an excellent column in Bird Watcher's Digest, editor Eric Blom writes of "growing evidence that huge numbers of birds have been killed by WNV, especially crows, jays, hawks, and owls." He then extrapolates from the number of great horned owls found dead in the upper Midwest to suggest that between 40,000 and 400,000 of them were killed. Even that lower estimate represents a great many birds of a single species.
Sadly, as Blom points out, infected birds have been brought to rehabilitators. The disease is communicated to other birds in their care with many dying. The rare northern owls at Mrs. McKeever's Owl Foundation in St. Catharines, Ont. were especially hard hit. Also some exotic zoo birds are being infected, including some at our Buffalo Zoo. Of special concern to wildlife managers is the welfare of rare wild birds like the California condor and the whooping crane.
The spread of this disease among birds suggests a rapid increase in incidence. So too does its dispersal across the country. It has already reached California, well ahead of earlier projections. More numbers suggest the pace of spread: in 1999, 4 states; in 2000, 11 states; in 2001, 27 states; and in 2002, 43 states.
What is happening? There is speculation that the disease is being spread among birds during their winter sojourn in the South by local mosquitoes acting as vectors there. That would explain the unexpectedly rapid spread of the virus across the country. Once the infected birds return, they are bitten by northern mosquitoes and those communicate the disease to, among other species, us.
This year the human disease incidence peaked in September and October. Five-sixths of the cases and deaths occurred then. Perhaps that delay was due to our very dry summer.
Clearly West Nile Virus is a serious disease. We should prepare for a difficult mosquito season in 2003.-- Gerry Rising