Indirect Hem agglutination Assay For Diagnostic and Epidemiological Studies of Visceral Leishmaniasis in Ethiopia
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Date
2005-06
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Addis Ababa University
Abstract
Visceral leishmaniasis (VL) is potentially a fatal disease that is caused by intracellular protozoan
parasites of the L. donovani spp. To date, there has been no reliable diagnostic test for active
infection of VL. Therefore, there is an urgent need for a simple, rapid, and reliable diagnostic test
with high sensitivity and specificity for clinical practice and VL control. To determine the
diagnostic and sero-epidemiological screening performance of Indirect Hemagglutination, serum
samples were obtained from endemic areas of Ethiopia and evaluated using antigens prepared
from an isolate of L. donovani (MHOM/SD/68/1S) promastigote stage. Serum samples of 77
suspected VL and 51 controls for diagnostic; and for epidemiological study 1217 samples
involving 57 VL suspected, and 1085 samples including 132 samples from previously treated VL
patients were tested by IHA at various cut-off titers, DAT, and FAST. Spleen and/or lymph node
aspiration with subsequent smear and/or culture test confirmed the presence of parasite in 37 and
19 individuals in diagnostic and epidemiological study subjects, respectively. IHA test performed
for comparison was able to detect anti-leishmanial antibodies in 94.6% and 100% of the
confirmed cases of VL (at 1:64 cut-off titer) in diagnostic and epidemiological study subjects,
respectively. Among 1085 sera, IHA (at 1:64 cut-off titer) test was positive in 10.6% of
previously untreated asymptomatic individuals. Whereas out of 132 previously treated VL
patients, 72% were found to be IHA positive at 1:64 dilutions. IHA at cut-off titers 1:64 and
1:128 showed a sensitivity of 94.5% and 86.5%, a specificity of 60% and 77.5% respectively in
the diagnostic study and a sensitivity of 100% and 100%, specificity of 33.3% and 50% in the
epidemiological study. The result showed IHA to be sensitive, rapid, and simple test for thediagnosis and epidemiological screening of visceral leishmaniasis. Further evaluation of IHA test
should be conducted with careful use of the gold standard.
Keywords: Indirect Hemagglutination test; Visceral Leishmaniasis; Ethiopia; seroepidemiology
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