The question must be asked whether there is a place for diagnostic and prognostic laboratory testing for FIP at all. There are presently no diagnostic assays available - neither in-practice tests nor assays performed in the research laboratory - that would distinguish between virulent (FIPV) and avirulent FCoV variants. Also the 'novel' PCR formats touted by some firms do not keep this promise, irrespective of the claims. We have reasons to believe that discriminatory assays based on the molecular properties of the variants will not be feasible, perhaps not even possible. However, there is a future for tests based on the evidence of immunological changes in an animal developing FIP.

Both serology and PCR are able to detect infected cats, with different sensitivity, and are invaluable for the management of catteries. They can be used for monitoring the success of the quarantine and 'early weaning' programmes, for controlling the specified pathogen-free and the coronavirus-free status of catteries. Especially PCR could be useful for monitoring individual animals to be introduced into FCoV-free catteries.

A promising approach to controlling FIP - based on isolation of litters after early weaning - has been developed by the Glasgow group [1] - but it is laborious, requires the dedicated cooperation of cat owners and has no veterinary appeal. Incidentally, other studies performed under similar conditions showed only marginal effects [7]. Another possibility is the removal of strong shedders from a multi-cat society. These can now be recognized by using the TaqMan technique: for a reliable characterization of the shedding pattern it is sufficient to test four feaces samples taken at weekly intervals. Strong shedders can be identified under field conditions and separated from the group, thereby decreasing infection pressure for the remaining cats. It remains to be shown whether this approach will work. However, common sense suggests that in conjunction with other measures (keeping cats in small groups, without contact between groups, frequent cleaning of litter boxes, introduction of new cats only after quarantine and PCR testing etc.) the elimination of strong shedders might be useful.

The seronegative catteries established through any control programme must of course be protected against re-introduction, and the live temperature-sensitive vaccine could prove useful for this purpose - if it indeed did not induce antibodies, thereby compromising a serology-based test-and-isolation programme. Also, persistence and recrudescence of the vaccine virus might then be studied. Still much must be learned about this most enigmatic infectious condition in veterinary medicine, feline infectious peritonitis.

References...

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