Feline leukemia virus infection: importance and current situation in Switzerland

Abstract

Feline leukemia virus (FeLV) leads to fatal disease in cats with progressive infection. The aim of this study was to determine the importance of FeLV infection in Switzerland and make a comparison with previous studies. Of 881 blood samples taken from cats living in Switzerland (minimum of 20 samples per Canton), 47 samples were provirus-positive (5.3%; 95% confidence interval (CI) 3.9-7.0%) and 18 samples were antigen-positive (2%; 95% CI 1.2-3.2%). Together with data previously collected in similar studies, these findings demonstrated a decrease in prevalence between 1997 and 2003 followed by a relative constant low prevalence thereafter. Young cats (=2 years) were more frequently infected than older cats, but FeLV-positive cats were up to 15 (antigen-positive) and 19 (provirus-positive) years old. Sexually intact cats were more frequently viremic than neutered cats; purebred cats were somewhat less frequently FeLV-positive than non-purebred cats. In a second study, in which 300 saliva samples were analyzed, samples from 5 cats were FeLV-RNA positive (1.7%; 95% CI, 0.5-3.8%), although one young feral cat had been falsely assumed to be FeLV-negative based on a point-of-care test. Of the 300 cats, only 50% were FeLV tested or vaccinated, although 90% of the cats were at risk of exposure to FeLV. Testing and vaccination of all cats with exposure risk may help further decrease the prevalence of FeLV infection. Moreover, characteristics of FeLV tests should be considered, such as the risk of false negative results in the early phase of infection when performing antigen testing.

The Diagnosis of Feline Leukaemia Virus (FeLV) Infection in Owned and Group-Housed Rescue Cats in Australia

“…The potential for errors with sample handling and labelling or laboratory contamination leading to discordant and unexpected results is unlikely, but cannot be absolutely excluded. Regardless of the classification system employed, p27-positive cats had mostly low qPCR C T values (15/21 less than 25), while p27-negative cats had mostly high qPCR C T values (29/31 higher than 30) [6,33]. As anticipated, presumptively progressively-infected cats were found to be more likely vRNA-positive than presumptively regressively-infected cats [29].…”

“…In many countries, the prevalence of feline leukaemia virus (FeLV) infection in domestic cats has decreased since the 1970s and 1980s [1,2]. For example, in parts of Australia, Europe, and North America, prevalence rates of 1–6% have been reported in the past decade [3,4,5,6]. This decrease has been attributed to veterinary interventions, including rigorous testing combined with vaccination, and isolation or euthanasia of infected animals [2,7].…”

Prevalence, Geographic Distribution, Risk Factors and Co-Infections of Feline Gammaherpesvirus Infections in Domestic Cats in Switzerland

“…The study included two sets of feline blood samples. First, the study included 881 EDTA-anticoagulated blood samples collected from domestic cats presented to veterinarians in Switzerland between 2013 and 2016 [37]. The study was designed to include at least 20 blood samples from each of the 26 Swiss cantons, and samples were selected only by the postal code associated with the cat owners.…”

“…The study was designed to include at least 20 blood samples from each of the 26 Swiss cantons, and samples were selected only by the postal code associated with the cat owners. The samples had been described and analyzed for FeLV provirus and antigen, and the results were previously presented elsewhere [37]. The samples were collected as part of a diagnostic workup by veterinarians for routine purposes, and only the remaining sample volume was used for this study.…”

“…Total nucleic acid (TNA) samples were extracted from 100 µL of EDTA-anticoagulated blood using a MagNaPure LC Total Nucleic Acid Isolation Kit (Roche Diagnostics, Rotkreuz, Switzerland) following the manufacturer’s instructions as reported previously [37]. All TNA samples were stored at −80 °C until further use.…”