Table 3 Advantages and disadvantages of common diagnostic methods for the detection of L. infantum infection in dogs.
From: LeishVet guidelines for the practical management of canine leishmaniosis
DIAGNOSTIC TECHNIQUES | ADVANTAGES | DISADVANTAGES |
|---|---|---|
SEROLOGY | • Determination of antibody level which is essential for the diagnosis and establishing a prognosis | • Does not detect the actual presence of the Leishmania parasite • Serocrossreactions with trypanosomes |
QUALITATIVE | • Rapid in-clinic test | • Provides only positive or negative result • Variable sensitivities and performance with risk of false negatives • A positive result needs to be further evaluated by a quantitative serology |
QUANTITATIVE (IFAT, ELISA) | Determines the antibody level • High antibodies levels in the presence of compatible clinical signs and/or clinicopathological abnormalities are conclusive of clinical leishmaniosis | • Performance and accuracy of cut-off will depend on the laboratory • Differences between laboratories and poor standardization of techniques • Low antibody levels will require further work-up |
CYTOLOGY/HISTOPATHOLOGY | Permits direct detection of the parasite itself and the type of pathological findings: - Pathological findings suspicious of infection - Allows exclusion of other differential diagnoses - Rapid and non invasive (cytology) | • Low sensitivity for the detection of Leishmania amastigotes in tissues or body fluids • Requires the performance of other diagnostic tests such as immunohistochemistry and/or PCR when parasites are not visualized • Does not reveal the immunological status of the dog • Needs expertise |
PCR | • Allows the detection of leishmanial DNA • High sensitivity (kDNA) and specificity • Parasitic load quantification (if Real time-PCR) | • False positive results possible due to DNA contamination • Different standardization and techniques used by different diagnostic laboratories • Does not reveal immunological status • It cannot be performed as the sole diagnostic technique for the confirmation of the disease because a positive result confirms Leishmania infection but not disease |
PARASITE CULTURE | • Permits the isolation of Leishmania parasites • Facilitates the isoenzymatic identification of the parasite | • Time-consuming and laborious diagnostic technique • It can require one month to provide a result • Performed only in research laboratories |