Diagnostic methods used for FeL.
IFAT (cut off: 1:80)
ELISA (lab. validated cut-off values)
DAT (cut-off: 1/800)
Western blot (detection of 18 KDa band)
Cytological evaluation of skin, mucosal or mucocutaneous lesion, lymph node and bone marrow smears (Figure 7)
Histological evaluation of skin, mucosal or muco-cutaneous biopsied lesions (± IHC and/or PCR)
PCR from skin, mucosal or muco-cutaneous lesion, lymph node, bone marrow, blood, conjunctival and oral swabs
Culture of skin, mucosal or mucocutaneous lesion, lymph node, bone marrow and blood samples
DAT: direct agglutination test; ELISA: enzyme-linked immunosorbent assay; IFAT: indirect fluorescence antibody test; IHC: immunohistochemistry; PCR: polymerase chain reaction.
To confirm diagnosis, a quantitative serological test or Western blot should be performed in sera from cats with clinical signs or clinicopathological abnormalities compatible with FeL. However, in case of negative or low-positive antibody titers, a parasitological technique should be used to identify infection (cytology, histology, PCR or culture), before discharging diagnosis.
Evaluation of Leishmania-specific serology and PCR techniques (blood, lymph nodes or conjunctival swabs) are recommended in the following special situations in endemic areas:
- Blood donors
- Cats requiring immunosuppressive therapies
- Before re-homing cats to non-endemic areas
Figure 7: Fine needle aspirate of a reactive lymph node: lymphoid hyperplasia and a macrophage with L. infantum amastigotes (red arrows). May-Grünwald-Giemsa stain, scale bar = 20 μm (© Maria Grazia Pennisi)