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On Jul 2, 2004, at 9:45 PM, Dylan Ford wrote:
. . .I enclose here material regarding West Nile Virus lifted in part 
and without
> permission from a Red Cross web site.
. . .
> There is no
> specific treatment for WNV infection or vaccine to prevent it.
. . .
 No cases of West Nile Virus attributed to transfusion of blood or blood
> products have been reported either in the US or in other areas of the 
> world
> with previous epidemics. While there is a theoretical possibility that 
> WNV
> can be transmitted by blood transfusion the risk is regarded as 
> extremely
> low. In areas where there are human cases, the low theoretical risk is
> further reduced by careful attention to existing donor screening 
> procedures.

I think this information was out of date in two places.  (And I note 
that it listed the number of people to catch the disease in the US only 
up through 2002.)

First, there is an effective vaccine, but it has only been approved for 
horses.  West Nile is a more serious problem for horses than for people 
(a much larger percent become infected when exposed, and a larger 
fraction of those go on to become seriously ill) and the vaccine 
manufacturers saw a solid market among thoroughbred breeders.  Also, 
it's much cheaper to develop a horse vaccine than a human vaccine.  You 
can intentionally expose cheap animals to the virus to test possible 
vaccines, and if there is some long-term or rare problem that shows up 
after the vaccine is marketed, your maximum liability is the cost of 
the horse.  Second, I'm pretty sure there has been one documented case 
of West Nile spreading either through a transfusion or a transplant - I 
forget which.

There's a reason beyond cost that there isn't a human vaccine.  It's a 
really rare human disease - even in areas with very high levels of 
virus (such as where I live, judging by the crows) people almost never 
catch it.  It's like equine encephalitis, St. Louis encephalitis, and a 
whole host of rare bug-born diseases that we've had for years - bad 
news if you catch it, but not a major public health threat.  
Personally, I'm much more scared that malaria might make a comeback in 
the temperate climes than I am of West Nile.  I'd rather we not have 
it, of course.  (In part because I really like crows, and in part 
because of the human risk) but "not having it" is no longer an option, 
and I don't think we need to do extraordinary things to avoid it.  
Besides, odds are your neighborhood will be infected whether or not 
your neighbors put out bread for the birds.

Ginda