PCR testing of conjunctival swabs to detect feline leukaemia virus in domestic cats in Thailand

This study aimed to classify the Feline leukaemia virus (FeLV) infection outcomes in domestic cats in Thailand and determine the accuracy of conjunctival swabs for FeLV proviral DNA detection by comparing results to PCR testing of blood samples. Whole blood and conjunctival swabs were collected from 126 cats with and without clinical signs. Blood specimens were evaluated for p27 FeLV antigen using the SNAP Feline Immunodeficiency Virus (FIV)/FeLV Combo Test, IDEXX Laboratories. The 3'-LTR region of the proviral FeLV was amplified from both blood and conjunctival samples. The prevalence rates of progressive and regressive FeLV infections in this study were 14.3% (95% CI: 8.69-21.63) and 36.5% (95% CI: 28.12-45.55), respectively. Cats older than 12 months of age had a higher probability of being regressively infected than cats younger than 1 year (<i>p</i>-value = 0.039, OR =0.294, 95% CI: 0.092-0.942). Conjunctival swabs used for detecting FeLV proviral DNA demonstrated a sensitivity of 95.3% (95% CI: 86.91-99.02) and a specificity of 100% (95% CI: 94.22-100.00) compared to conventional blood samples. The observed kappa value of 0.956 indicates that conjunctival swabs are reliable and can be used as an alternative to blood venipuncture.