BackgroundThe lungwormAelurostrongylus abstrususinfects wild and domestic feline species worldwide and is considered a primary respiratory parasite of cats. Definitive diagnosis is based on the identification of first-stage larvae (L1s) released in faeces approximately 5 to 6 weeks after infection. More recently, serology has been shown to be a diagnostic alternative forA. abstrususinfection in cats. The present study aimed at evaluating the diagnostic performance of serological antibody detection compared to faecal examination forA. abstrususinfection in a population of cats with known infection status from endemic areas in Italy and to identify factors (larval scores, age, co-infections with other helminths) that may influence test sensitivity and specificity of serology.MethodsAll cats resulting positive using the Baermann technique (n= 78) were tested with theA. abstrususELISA. An additional 90 serum samples from cats living in three geographical areas with infection prevalence > 10%, but that resulted negative on Baermann, were also tested.ResultsAmong 78 cats copromicroscopically positive for L1s ofA. abstrusus(Group 1), 29 (37.2%) were seropositive in ELISA. Of the 90 cats from Group 2 (cats living in three geographical areas in Italy withA. abstrususprevalence > than 10%, but negative on Baermann examination), 11 (12.2%) were positive on ELISA. The overall seroprevalence was 23.8%. There was no statistical difference either between average optical density (OD) values of cats excreting > 100 L1s vs. cats excreting < 100 L1s (0.84 vs. 0.66;Pvalue = 0.3247) or comparing the OD values with age of infected cats. Few Baermann-negative cats positive forToxocara catior hookworms were seropositive, supporting lack of cross-reactivity to these nematodes.ConclusionsResults from the present study suggest that relying solely on faecal examination may underestimate prevalence ofA. abstrususinfection in cats and that field surveys based on antibody detection are useful for establishing true prevalence of infected and/or exposed animals.Graphical Abstract