An enzyme-linked immunosorbent assay (ELISA) for the detection of IgM antibodies against Leishmania chagasi in dogs

Abstract

Visceral leishmaniasis is an emergent zoonosis with an increasing number of new cases in Brazil where the domestic dog is an important parasite reservoir in the infectious cycle of Leishmania chagasi. An enzyme-linked immunosorbent assay (ELISA), based upon the use of a total soluble antigenic preparation of L. chagasi, was adapted for the detection of IgM antibodies in the serum of infected dogs. Optimal dilutions of the antigen, using positive and negative reference sera, were determined by checkboard titrations. The specificity and sensitivity of the ELISA were 100 %. A total of 110 serum samples were taken from dogs in Belo Horizonte, Minas Gerais, Brazil, and examined for anti-L. chagasi IgM antibody by ELISA and indirect fluorescent antibody test (IFAT). About 25% (n=27) of all the dogs tested were found serologically positive for L. chagasi by IFAT, while 89.09% (n=98) were seropositive by ELISA. The results obtained by ELISA and IFAT were significantly different (P<0.01). The combined use of ELISA and IFAT is recommended in order to enable veterinary services to more efficiently detect canine visceral leishmaniasis.INDEX TERMS: Leishmania chagasi, diagnosis, dogs, IgM, enzyme-linked immunosorbent assay.

Evaluating the Accuracy of Molecular Diagnostic Testing for Canine Visceral Leishmaniasis Using Latent Class Analysis

“…Although splenic aspirate collection is considered an invasive procedure by many dog owners [27] , [72] , Barrouin-Melo et al (2006) noted that minor complications were observed in only three out of 257 dogs that underwent splenic aspiration. Complications can be further minimized by visualizing the spleen using an ultrasound device to guide splenic aspiration [72] , [73] .…”

“…However, molecular diagnostic tests in studies using these tissue types have produced variable, and sometimes conflicting results, for identifying Leishmania -infected dogs [19] , [25] , [26] . This might be because culturing the parasite, which has been used as the gold standard assay [27] , [28] , has a low sensitivity threshold for detecting dogs with a low parasite burden [29] , [30] , which compromises the accuracy evaluation of diagnostic testing.…”

Validity and Reliability of Enzyme Immunoassays Using Leishmania major or L. infantum Antigens for the Diagnosis of Canine Visceral Leishmaniasis in Brazil

“…Similar results (97% sensitivity and 98% specificity) have been reported by Scalone et al [28] for a sample of 415 animals (258 negative and 157 positive ) using recombinant rK39 antigen. Carvalho et al [29] observed 100% sensitivity and specificity of an in-house ELISA using L. infantum antigen in 125 animals (15 negative and 110 positive ). The fact that another serological test was used as the gold standard in those studies might be a disadvantage since the tests evaluated would detect the same phenomenon of antibody elevation identified by the gold standard and the chance of agreement would therefore be higher, overestimating sensitivity and specificity.…”

New Advances in the Diagnosis of Canine Visceral Leishmaniasis

“…Splenic collection, bone marrow and lymph node aspirates are considered invasive procedures [153] in addition to having an elevated cost compared to blood collection. Thus, it can be recommended to use samples obtained less invasively, such as blood and conjunctival swabs [136,154,155].…”

“…Several diagnostic strategies have been implemented based on parasitological, serological or molecular methods in association with clinical and epidemiological parameters [21]. Parasite culturing has been considered as gold standard for disease diagnosis [22,23]. Although offering a high specificity since allows parasite identification, it offers very low sensitivity, besides it is laborious, time-consuming and largely dependent on the expertise of the observer [24,25].…”