Thanks for your reply Beth. I'm an engineer and I'm trying to make sense
out of the tests...and what you said isn't all making sense to me yet :).

The kittens had been separated from their mother for most of their lives.
The mother was an outside-cat and died/disappeared right after the kittens
were born. My nephew hand-fed the litter and we adopted two of five
original kittens. They would have been un-exposed to other cats for more
than six months before we tested them originally. The original Elisa should
have been positive because we had them for 90 days before spaying them and
they were in my nephew's care for many more months before that. The vet
also latches onto that period as originating their exposure to the
virus...because nothing else makes sense. The cat community lives in my
sister's barn in a rural section of Wisconsin...she has put many cats up
for adoption and has never had a case of FeLV in any of the their cats to
date.

The IFA detects viral protein either in the blood or blood cells. If Tux
had anemia from FeLV itself then the virus would have to be very active in
the bone marrow and blood, or, her immune system was compromised and she
got a parasitic infection...also involving FeLV in the bone marrow. In both
cases, with something as severe as anemia presenting, the IFA would be
positive. It doesn't make sense that the IFA could be negative under these
circumstances. From what I read you don't get anemia on initial exposure to
the virus...the anemia is a side effect of serious infection of the bone
marrow and white blood cells.

Here is what I read about the snap test online (considering the source):
1) There is room for interpretation of the results by the technician (color
detection). Sometimes the color is very faint or an over-zealous tech can
see a faint color when there is none.
2) Some other antibodies in the blood can cross-react with the
elisa...giving a false positive.
3) First two issues aside, the test is 95% accurate. IFA is over 99%
accurate.

Thanks again for your reply...I guess I'm having a hard time understanding
why the IFA was negative in such a severe case of anemia and how Tux could
ever have been exposed to the virus.

Thanks. Dave
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