Unusual FeLV situation

[smokey the elder]

I have a very unusual situation with some of my fosters. In April 2008 my rescue group took in a litter of kittens. In June they tested both FIV and FeLV positive, so were transferred to my place where they could be isolated. The vet recommended that they be retested at 4 months. At 4 months they all tested negative for FIV and positive for FeLV. (These all used the ELISA test.) They had no symptoms whatsoever.

Then in September, I got them altered since they were of mixed gender. The spay/neuter went without incident. We decided to run a different test called IFA. This was negative! However, a repeat ELISA was positive. (For FeLV only.)

Now it gets weird... at one year of age (kittens still asymptomatic) I decided to take ONE kitten (Linus) in to have the ELISA test repeated...it was negative. He was stashed away from the rest of the litter, who ended up testing positive. This result was confirmed in June 2009. (IFA was not repeated due to low funds in the rescue group.) Linus' negative result was confirmed yesterday.

Neither the vet nor I have ever heard of this happening, where one kitten from a litter stops shedding FeLV virus, but the others still test positive over one year later. I didn't have much joy googling it either. I was wondering if any of you folks had ever observed anything like this.

(My rescue group does not euthanize asymptomatic FIV/FeLV cats/kittens.)

[Lizzie]

I haven't been in your situation where a postive turned negative after such a period of time, but the following web site indicates that different results can be obtained not just through a different test (ISA) but also whether whole blood or blood plasma is used. In fact, there seem to be a number of variables.

http://www.vin.com/mainpub/feline/aafpfelvdx.htm

My own experience was a litter of 3 kittens where one, by far the weakest, tested positive on the ELISA at 8 weeks but other two were negative. The positive kitten was isolated. Six weeks later all three were re-tested and that showed the original positive cat was still positive, one of the negative cats had become positive (Seshat) and the other (Ted) remained negative. Whether this was because the positive kitten infected one of the other kittens during the first eight weeks, we don't know. The two positive kittens were isolated together. The weakest kitten (Roo) died at 8 months. I continued to have the positive and negative kittens tested and they remained the same even though I reunited Ted and Seshat and they lived together for the next 6 years. Although Ted always tested negative, he definitely had a weak immune system.

I'm really pleased for you that one of the cats apparently threw off the virus.

[jenluckenbach]

Never seen this either, BUT.....here is a situation, in reverse. Maybe it is similar.

A coworker had a cat die of FELV. the cat had always tested negative.

The vet said FELV can "hide" in the bone marrow. I wonder if it can MOVE into the bone marrow, to possibly come out at a later date??

[Freedom]

(My rescue group does not euthanize asymptomatic FIV/FeLV cats/kittens.)

Nor does the one I work with.

That sure is a surprise, quite interesting development. I am also surprised how many times those kittens (now cats, at a year old +) have been tested! Are you just determined to get them all negative? Can't believe the tests?

My group usually tests once, a second time after age 6 months if they were initially positive.

Maybe your vet can write an article and get it published! Or, some grad student may love to work with this litter for a study.

I don't have any FeLV, but Bobby is FIV positive. We tested him twice and then did the Western Blot test. No symptoms, now over 2 years old. But he is the reason I not longer bring any cats into the home; I don't want to stress his immune system.

[smokey the elder]

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.

[Lizzie]

The vet said FELV can "hide" in the bone marrow. I wonder if it can MOVE into the bone marrow, to possibly come out at a later date??

That's what the vet suggested happened with Ted, that the virus was in his body (bone marrow) but hiding. He lived to 12 years and died of renal failure, but he never was in truly robust health. The virus seemed to be on a slow simmer all his life, hidden but effective, and never became full blown. I'm sure there is a lot more they have to learn about this virus.

The shelter where I volunteer has an area (including an outdoor enclosure) just for their FeLV+ cats. They do follow up the ELISA with an IFA test to be sure.

When Seshat tested positive I was told to expect at most three years but she lived for seven in part, I think, because she was old-style Siamese which is a tough and long-lived breed and partly because I pretty much dedicated my every waking and non-working-for-a-living moment to her. It was wrong of me because the other cats were side-lined too much but I think it gave her an edge to fight off any infections that came her way. It also made losing her that very much harder, I had a hard time hanging onto reality for the first few days.