Dear Susan: The fact the kittens tested a "faint positive" (an ELISA, right?) is probably an indication of exposure and some virus present (both the ELISA and IFA detect anitgen from replicating virus) but may still be an earlier stage of infection so there is a chance with good diet and immune support these kittens can clear the virus. A truly "false positive" on the ELISA would be for viral antigen to be detected when none was present. What is more likely, given the sensitivity of the ELISA test which can detect even minute amounts of antigen, is that "faint" positive results indicate an early stage of infection, and that cats/kittens who initially test postive, then later test negative, were able to clear the virus, or, the infection could have become latent.
If the other cats in the foster household are healthy adults, I would not be very worried that the kittens may pass the virus to them, but be most concerned that the kittens get the best possible diet and immune support to help their immune system fight off the virus. Any further assaults, be it emotional, environmental or from anything the other cats may bring to the table, to their immune system should be minimized. A negative IFA at this point could confirm an infection has not progressed to the point of no return and there is still a good chance to clear it, but would also represent the significant stress of a blood draw. If one has the resources, a good strategy is to ask the vet or tech to draw enough blood initially so that if the ELISA result is positive, then an IFA can then be run to confim it as either stage 4 or beyond, or still in stage 1-3. My advice would be to transition those kittens to a raw, natural diet (or the best commercial food possible such as Wellness or Innova, etc.) with good immune support supplementation such as Transfer Factor, Vit. C, CoQ10, etc. and try to keep their lives as stress-free as possible, which would include no, or mininal, vaccines. Do keep them indoors and away from any cats who go outdoors that may bring unwanted pathogens to bear. I would then retest them in 45-60 days. Here's hoping... Sally in San Jose
