Serological diagnosis of canine leishmaniosis: comparison of three commercial ELISA tests (Leiscan®, ID Screen® and Leishmania 96®), a rapid test (Speed Leish K®) and an in-house IFAT

Abstract

BackgroundSpeed Leish K® is used as a serological screening test for Leishmania infection prior to vaccination. Limited comparative serological studies with Speed Leish K® have been performed. The aim of this study was to evaluate the diagnostic performance of four commercially available serologic tests including ELISAs (Leiscan®, ID Screen® and Leishmania 96®), a rapid test (Speed Leish K®) and an in-house IFAT for the detection of specific antibodies against Leishmania infantum antigen in dogs in different states of infection.MethodsSick infected dogs (n = 36), healthy infected dogs (n = 18), L. infantum seropositive dogs with low to high levels of antibodies (n = 53), dogs seropositive to other pathogens (to evaluate cross reaction) (n = 14) and uninfected dogs from a non-endemic area (n = 50) and from an endemic area (n = 32) were analysed by the serological methods mentioned above.ResultsThe sensitivity was as follows: ID Screen® (0.953), Leiscan® and Leishmania 96® (0.925), IFAT (0.869) and Speed Leish K® (0.636). The maximum specificity (1.000) was attained for all diagnostic tests except the Leishmania 96® (0.896) and IFAT (0.917). The accuracy was as follows: ID Screen® (0.975), Leiscan® (0.961), Leishmania 96® (0.911), IFAT (0.892) and Speed Leish K® (0.808). In relation to the area under the ROC curve (AUC-ROC), the maximum value was attained with the ID Screen® (0.993) closely followed by Leiscan® (0.990), then, Leishmania 96® (0.962), IFAT (0.926) and Speed Leish K® (0.818). For the Kappa index, the best result was obtained by the ID Screen® (0.951) followed by Leiscan® (0.921), Leishmania 96® (0.822), IFAT (0.783) and Speed Leish K® (0.622). Statistically significant differences were found between the AUC-ROC of quantitative serological tests and the only qualitative rapid test evaluated. There were also statistically significant differences between AUC-ROC of the ELISAs (ID Screen® and Leiscan®) and IFAT.ConclusionsLeiscan® and ID Screen® had superior diagnostic performance measures than IFAT and all quantitative serological tests were superior when compared to Speed Leish K®. Thus, Speed Leish K® may be considered a less valuable screening test prior to vaccination as it may result in vaccination of seropositive dogs and in some cases seropositive sick dogs.

Managing the spread of canine leishmaniosis in Europe

“…The gold standard for diagnosis is observing parasites in bone marrow or lymph node aspirates, but this has a low sensitivity even when performed by well-trained staff. Therefore, diagnosis is usually confirmed by serology and, increasingly, by rapid immunochromatographic dipstick tests incorporating one or more recombinant kinesin antigens, instead of immunofluorescence antibody tests (IFATs) and ELISAs that often vary among laboratories (Franco and others 2011, Solano-Gallego and others 2014). Diagnostic PCR tests are available to identify the other Leishmania species that can cause canine leishmaniosis in some regions (Gebhardt and others 2015), notably Leishmania tropica in south-east Europe, North Africa and the Middle East (Ready 2013).…”

“…Clinical presentation was variable and all the clinics used at least one serological test for diagnosis confirmation, as reported in other questionnaire-based studies in south-west Europe (Ballart and others 2013, Bourdeau and others 2014). IFAT is the gold standard in serological diagnosis, but ELISAs were most often used in Girona (80 per cent) and, depending on the commercial kit and the clinical status of the dog, they can be more reliable (Solano-Gallego and others 2014, Lladró and others 2016). Early diagnosis of canine leishmaniosis cases is critical for a good prognosis.…”

Different Patterns of Fluorescence in the Quantisation of anti-Leishmania Infantum Antibodies by Indirect Immuno-Fluorescent Antibody Test (IFAT) in the Serological Diagnosis of Canine Leishmaniasis

“…The use of specific antigens have some limitations [13], and a crude extract is widely employed for general diagnostic purpose [5] [7] [8]. ELISA is described as a method that does not require a specialized technician to understand the results obtained from the microplate reader, and non-specific reactions are controlled by the use of an appropriate cut-off [14].…”

Leishmaniosis in dogs and cats

“…The IFAT is considered the reference method for anti- Leishmania serology in dogs (Gradoni and Gramiccia 2008, EFSA AHAW Panel 2015) based on its high sensitivity and specificity (near 100 per cent for both) except in areas endemic for Trypanosoma cruzi where it may give false positive results. ELISA is also very sensitive and specific (near 100 per cent for both) when a combination of immunodominant recombinant proteins is used as antigen; it has slightly lower specificity when crude parasite lysates are employed instead (Maia and Campiono 2008, Rodríguez-Cortés and others 2010, Solano-Gallego and others 2014). …”