Because few groups will test more than once, there just not may be enough data available. From everything I've read, and observations in my rescue group, FeLV positive kittens become sickly within a year, and only live 2-3 years max. However this letter has never been sick (knock wood) other than routine kitten URI's that were easily managed.

That's a neat idea about following the kittens; if the vet thinks this is publishable I might be able to get them to spring for both the ELISA and IFA tests; or I just might do it. The game plan was to get at least an ELISA done on their birthday (mid April) as long as they are asymptomatic.