Field evaluation of a coproantigen detection test for fascioliasis diagnosis and surveillance in human hyperendemic areas of Andean countries - PubMed (original) (raw)

Comparative Study

doi: 10.1371/journal.pntd.0001812. Epub 2012 Sep 13.

María Victoria Periago, Ignacio Pérez-Crespo, René Angles, Fidel Villegas, Carlos Aguirre, Wilma Strauss, José R Espinoza, Patricia Herrera, Angelica Terashima, Hugo Tamayo, Dirk Engels, Albis Francesco Gabrielli, Santiago Mas-Coma

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Comparative Study

Field evaluation of a coproantigen detection test for fascioliasis diagnosis and surveillance in human hyperendemic areas of Andean countries

María Adela Valero et al. PLoS Negl Trop Dis. 2012.

Abstract

Background: Emergence of human fascioliasis prompted a worldwide control initiative including a pilot study in a few countries. Two hyperendemic areas were chosen: Huacullani, Northern Altiplano, Bolivia, representing the Altiplanic transmission pattern with high prevalences and intensities; Cajamarca valley, Peru, representing the valley pattern with high prevalences but low intensities. Coprological sample collection, transport and study procedures were analyzed to improve individual diagnosis and subsequent treatments and surveillance activities. Therefore, a coproantigen-detection technique (MM3-COPRO ELISA) was evaluated, using classical techniques for egg detection for comparison.

Methodology and findings: A total of 436 and 362 stool samples from schoolchildren of Huacullani and Cajamarca, respectively, were used. Positive samples from Huacullani were 24.77% using the MM3-COPRO technique, and 21.56% using Kato-Katz. Positive samples from Cajamarca were 11.05% using MM3-COPRO, and 5.24% using rapid sedimentation and Kato-Katz. In Huacullani, using Kato-Katz as gold standard, sensitivity and specificity were 94.68% and 98.48%, respectively, and using Kato-Katz and COPRO-ELISA test together, they were 95.68% and 100%. In Cajamarca, using rapid sedimentation and Kato-Katz together, results were 94.73% and 93.58%, and using rapid sedimentation, Kato-Katz and copro-ELISA together, they were 97.56% and 100%, respectively. There was no correlation between coproantigen detection by optical density (OD) and infection intensity by eggs per gram of feces (epg) in Cajamarca low burden cases (<400 epg), nor in Huacullani high burden cases (≥ 400 epg), although there was in Huacullani low burden cases (<400 epg). Six cases of egg emission appeared negative by MM3-COPRO, including one with a high egg count (1248 epg).

Conclusions: The coproantigen-detection test allows for high sensitivity and specificity, fast large mass screening capacity, detection in the chronic phase, early detection of treatment failure or reinfection in post-treated subjects, and usefulness in surveillance programs. However, this technique falls short when evaluating the fluke burden on its own.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. MM3-COPRO ELISA in feces from children (n = 436) from Huacullani (Northern Bolivian Altiplano).

Data points represent the mean absorbance at 492 nm obtained from three replicates of each sample tested. The dotted line represents the cut-off value 0.097 units of OD at 492 nm.

Figure 2

Figure 2. MM3-COPRO ELISA and intensity of Fasciola hepatica infection in the low burden group of Huacullani.

Data points represent the mean absorbance at 492 nm from egg positive children from Huacullani. epg represents the egg count per gram of feces. The dotted line represents the cut-off value 0.097 units of OD at 492 nm.

Figure 3

Figure 3. MM3-COPRO ELISA and intensity of Fasciola hepatica infection in the high burden group of Huacullani.

Data points represent the mean absorbance at 492 nm from egg positive children from Huacullani. epg represents the egg count per gram of feces. The dotted line represents the cut-off value 0.097 units of OD at 492 nm.

Figure 4

Figure 4. Theoretical PPVs and NPV values vs fascioliasis prevalence.

Curves show the expected PPVs (continuous line) and NPV (dotted line) values in low (below 1%), medium (between 1% and 10%) or high (above 10%) prevalence scenarios (expressed in vertical lines) in Huacullani (A) and Cajamarca (B).

Figure 5

Figure 5. MM3-COPRO ELISA in feces from children (n = 362) from Cajamarca valley (Peru).

Data points represent the mean absorbance at 492 nm obtained from three replicates of each sample tested. The dotted line represents the cut-off value 0.097 units of OD at 492 nm.

Figure 6

Figure 6. MM3-COPRO ELISA and intensity of Fasciola hepatica infection in the low burden group of Cajamarca.

Data points represent the mean absorbance at 492 nm from egg positive children from Cajamarca. epg represents the egg count per gram of feces. The dotted line represents the cut-off value 0.097 units of OD at 492 nm.

References

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