Quarantine protects Falkland Islands (Malvinas) cats from feline coronavirus infection

Abstract

Feline coronavirus (FCoV) causes feline infectious peritonitis (FIP). Since 2002, when 20 cats on the Falkland Islands were found to be FCoV seronegative, only seronegative cats could be imported. Between 2005-2007, 95 pet and 10 feral cats tested negative by indirect immunofluorescence antibody (IFA) analysis using two strains of type II FCoV, two transmissible gastroenteritis virus assays, an enzyme-linked immunosorbent assay and rapid immunomigration test. Twenty-four samples (23%) showed non-specific fluorescence, mostly attributable to anti-nuclear antibodies (ANA). The reason for ANA was unclear: reactive samples were negative for Erhlichia canis antibodies; seven were feline immunodeficiency virus positive, but 15 were negative. It was not possible to determine retrospectively whether the cats had autoimmune disease, hyperthyroidism treatment, or recent vaccination which may also cause ANA. The FCoV/ FIP-free status of the Falkland Islands cats should be maintained by FCoV testing incoming cats. However, ANA can complicate interpretation of IFA tests.

Utility of feline coronavirus antibody tests

“…The gold standard in FCoV antibody tests is generally regarded as the IFAT. However, as we found in this and a previous study, 17 IFATs from different laboratories do not always give the same result on any one sample. Therefore, to assess the sensitivity and specificity of a test, a panel of samples on which a consensus of results had been obtained was chosen in preference to a gold standard.…”

“…The negativity and positivity of samples in the panel had previously been determined. 12,17 Assessing the sensitivity of a FCoV antibody test requires the ability to determine accurately when a false-negative result has occurred. The sample panel included some challenging positive samples that gave false-negative or inappropriately weak-positive results on one or more FCoV antibody tests owing to the presence of large amounts of coronavirus in the sample.…”

An update on feline infectious peritonitis: Virology and immunopathogenesis

“…Although numerous strains of FECV are found among cats throughout the world, at least one population has remained surprisingly free of infection. Cats in the Falkland Islands have no signs of infection and attempts are being made to quarantine these cats from an inadvertent introduction of the virus (Addie et al, 2012). The long isolation of cats in the Falklands is indirect evidence that coronaviruses might not have existed in cats at the time of their transit to the island.…”

An update on feline infectious peritonitis: Diagnostics and therapeutics

“…The problem of laboratory contamination with PCR products can be avoided by using real time RT-PCR and, for this reason, virtually all PCR-based diagnostic tests for FECV/FIPV RNA are based on this format. It is generally conceded that real time RT-PCR is quite sensitive and specific in detecting and semi-quantitating fecal coronavirus (FECV) shedding in both experimental and naturally infected cats (Pedersen et al, 2008(Pedersen et al, , 2012Kipar et al, 2010;Vogel et al, 2010;An et al, 2011;Addie et al, 2012;Amer et al, 2012;Wang et al, 2013). However, a high sensitivity and specificity is conditional on a number of variables.…”