Potomac horse fever/vet questions

["Cheryl Shelton" <toltallyice@onewest.net>]

Heidi,

It's my understanding that current theory is that PHF is spread by a fresh
water snail. It seems to only be a problem when the water the snail is in is
warmed up, such as during the hot summer months or during a warm fall. We
have had at least five cases in our area at just one vet clinic. Including
one death. They all seemed to be living along the same canal. I do not
believe a horse can catch it from another horse. It appears to be spread by
contact with water inhabited by the snail. I'm not sure if it's a protozoa
or just what that becomes infective when the snail is in warm water????
Anyone??

I have been meaning to write ridecamp about PHF. Since the outbreak in our
area (Idaho), I am wondering how endurance riders are deal with the treat of
PHF since it is common for horses to drink out of streams and such. At least
one of the horses here had been immunized for PHF. Possibly others had also,
but I don't know that as a fact. I had a friend that also lost a horse in
this area to PHF years ago. I will definitely be paranoid when irrigation
season starts up again with all the cases of PHF we've had this year.

Any ideas? How big of a threat is this?? Is it mostly run down or health
challenged horses that are more susceptible, such as young or old? Is the
vaccine know to have a good effective rate?

Worried....

Cheryl