Low seroprevalence of Leishmania infantum infection in cats from northern Portugal based on DAT and ELISA

Cats have been considered playing a role in the epidemiology of leishmaniosis caused by Leishmania infantum, an endemic zoonosis in countries of the Mediterranean basin. The present study assessed the prevalence of antibodies to L. infantum in 316 domestic cats from northern Portugal, by means of the direct agglutination test (DAT) and an enzyme-linked immunosorbent assay (ELISA). Seroreactivity to DAT was found in six cats, and nine cats were positive in the ELISA, including the six DAT-positive animals. The overall seroprevalence of Leishmania infection was 2.8%, based on ELISA and DAT. A substantial agreement (99%; κ value=0.80) was found between DAT and ELISA results. The difference between seroprevalence values in females (0.7%) and males (4.7%) was statistically significant (p =0.045). The age of seropositive cats ranged from 31 to 84 months. Cats with 5-6 years (60-71 months) and 6-7 years (72-83 months) presented the highest level of seropositivity (15.4% and 33.3%, respectively). A significant difference was found comparing the seroprevalences in cats aged less than 24 months (0.0%) and in those with 24 months or more (7.3%) (p =0.022). Seroprevalences in cats living in a rural environment (10.5%) or in urban areas (0.0%) were also found to be significantly different (p <0.001). No significant differences were detected between serological status to Leishmania in pure non-European and European or mixed breeds (p =0.442), cats that lived totally indoors and those that had access to outdoors (p =0.412), cats seropositive and seronegative to Toxoplasma gondii (p =0.276), or apparently healthy animals and those with clinical illness (p =0.271). This study is the largest epidemiological investigation performed on feline Leishmania infection in Portugal. The seroprevalence of Leishmania infection was low in cats living in northern Portugal, a region where canine leishmaniosis is endemic. Nevertheless, Leishmania infection must not be underestimated and leishmaniosis may be included in the differential diagnosis of cutaneous or systemic clinical signs in cats.