Bruce Levine wrote:
 
> ... intranasal vaccines produce IgA which protects best against viruses
>that are mainly intestinal or respiratory.  Considering the systemic nature
>of the Canine Distemper virus, it is doubtful anything other than IgG
>(injection) would be protective.
 
I'm going to take a wait-and-see approach to that since the whole field of
mucosal immunity is relative recent (or recently revived from dormancy).  My
work is with sexually transmitted diseases, most of which *do* infect mucous
membranes.  There is much interest in intravaginal vaccines for STDs.
However, there is also great interest in mucosal vaccines for HIV, which is
very much a systemic disease.  The idea is to increase the potential for
immunity at the site where the virus enters the body.  For most viruses,
this is some type of mucous membrane such as the mouth, nose, or anogenital
area.  Some researchers think that using a vaccine in these locations may be
more effective than or at least a useful adjunct to systemic vaccines.  But,
this still isn't well researched at this point so I doubt anyone can
quantify the benefits--if any--of nasal or other mucous membrane vaccines.
 
>Actually, the rabies virus DOES pass through the placenta to the fetus
>in skunks. However this process has only been demonstrated in skunks.
 
Thanks for verifying this.  I don't understand the biology behind it since
rabies travels through nerve cells and the nervous system of the mother and
fetus are not associated as is the circulatory system.  I'll take your word
for it though and I'll see if I can find some explanation for the mechanism
involved.  (Any citations you know of?) Such information does not help the
efforts to convince the public and *some* state health officials that a risk
assessment and quarantine are sufficient in most bite incidents.  I worry
that for those who have a negative attitude toward "exotic" pets will use
such information to make ferrets guilty by association since ferrets and
skunks are both mustelids.
 
--Jeff Johnston
 
[Moderator's note: There have been a case of aerosol transmission of rabies
by spelunkers from bat guano - does that help or hurt the puzzle?  BIG]
[Posted in FML issue 1619]