Introduction of an improved direct agglutination test for the detection ofLeishmania infantum infection in Southern France

Abstract

An improved direct agglutination test (DAT) is assessed for the detection of Leishmania infantum antibodies in man and in the canine reservoir in Southern France. The test performance in 32 human visceral leishmaniasis patients was in agreement with the parasitological diagnosis and the immunofluorescence (IFAT) results. In six patients diagnosed earlier as kala-azar cases, both DAT and IFAT revealed negative results. The specificity of the DAT was reproduced in this study by the absence of cross-reactions with sera from other patients. In the dog reservoir, the DAT results were compared with those obtained by IFAT, the enzyme-linked immunosorbent assay (ELISA), cross-over electrophoresis and the latex agglutination test. All 34 dogs with parasitologically positive lymph node aspirates also had positive DAT titres (less than or equal to 1:640); the sensitivity in the other four tests was relatively low. Positive DAT and IFAT results were found in 16 unconfirmed cases of canine leishmaniasis, most probably due to prepatent L. infantum infections.

Reliability of serological methods for detection of leishmaniasis in portuguese domestic and wild reservoirs

“…This phenomena was earlier pointed out by other scientists (Lanotte et al 1979, Abranches et al 1991. A comparatively high prevalence rate has been reported in a dog population in the south of France (De Korte et al 1990). …”

“…The test was performed following the modified version for the canine reservoir (Harith et al 1989). According to previous studies on evaluation of DAT for the canine reservoir (Harith et al 1989, De Korte et al 1990, 1:320 titre was taken as a cut-off for L. infantum infection in the canine and vulpine hosts.…”

“…Being readily detectable after onset of infection, antibodies to L. infantum therefore, seem to be more sensitive parameters for monitoring of infections (Lanotte et al 1974, Abranches et al 1987. Epidemiological studies using other serological techniques including the counter-immunoelectrophoresis (CIEP) (Dieng 1985), latex agglutination (Dereure 1986), the enzyme-linked immunosorbent assay (ELISA) (Binhazim et al 1993) and the direct agglutination test (DAT) (De Korte et al 1990 revealed comparable high levels of endemicity.…”

Serological diagnosis of leishmaniasis: on detecting infection as well as disease

“…The former are certainly uninfected; the latter are individuals who have been found parasitologically or clinically negative, usually after a single examination. Some examples of this approach applied to both canine and human visceral leishmaniasis, among the very many which have been published, are in the references [3][4][5][6][7][8][9][10][11][12][13][14]. It has often been concluded, particularly when using nonendemic controls, that it is possible to choose a cut-off point (threshold titre) giving sensitivity and specificity close to 100%.…”

Operational validation of the direct agglutination test for diagnosis of visceral leishmaniasis.

“…6,8 Several investigators reported high accuracy of the test under laboratory conditions for VL due to Leishmania donovani, [9][10][11] as well as L. infantum. 12 Among the serologic assays recently developed, the DAT seemed most appropriate for use in the field. 11,13 The occurrence of disastrous VL epidemics in southern Sudan in the late 1980s created a pressing demand for appropriate diagnostic tests.…”