Humoral and cellular immune responses against Leishmania Infantum in cats

Free ranging animals are very common in Italy. Because of minimal or no preventative measures, they are exposed to vector-borne-pathogens and may be considered their sentinels such as for Leishmania infantum. Dogs are the main reservoir for L. infantum but many studies suggest the cat as apossible long-term host. The aims of this study were to provide information about health status and L. infantum infection antibody prevalence rates of 124 stray cats and 226 shelter dogs from Messina municipality (Sicily, Italy) and to assess associations between clinical data or retroviral feline coinfections and L. infantum infection. Animals were sampled between November 2014 and May 2016 and tested by the immunofluorescence antibody test (IFAT) (cut off 1:80). Data about age, physical examination and complete blood count (CBC) were collected. Positivity to FIV and FeLV was also investigated in 95 cats. Ninety-three per cent of dogs and 80% of cats presented one or more alterations at physical examination and CBC. Conversely, seroreactivity to L. infantum (titer ≥80) was significantly higher in dogs (44%) than in cats (18%). Flea infestation was found in about half of the cats and 22% were anti-FIV antibody positive. No cats were FeLV antigen positive. Prevalence of skin lesions and lymph node enlargement were significantly higher in antibody positive dogs and cats than in seronegative animals. However, low BCS, lymphocytosis, basophilia or eosinophilia were significantly more frequent only in seropositive dogs. This study confirms that in endemic areas a high L. infantum antibody prevalence is found in shelter dogs when preventative measures are not applied. Colony stray cats have a lower rate of antibody positivity but this is not negligible and can contribute to epidemiology of L. infantum in the investigated area. The role of FIV coinfection in the susceptibility of cats to L. infantum infection should be assessed by staging FIV infection. Antibody positivity is associated in both dogs and cats with clinical signs compatible with leishmaniosis. Flea infestation is a common occurrence in stray cats and they therefore have an important role in maintaining and spreading fleas in the territory.