Performance of a real-time PCR approach for diagnosing Schistosoma haematobium infections of different intensity in urine samples from Zanzibar.
Control
Diagnosis
Dra 1
Elimination
Microhaematuria
Real-time PCR
Schistosoma haematobium
Surveillance
Urine filtration
Zanzibar
Journal
Infectious diseases of poverty
ISSN: 2049-9957
Titre abrégé: Infect Dis Poverty
Pays: England
ID NLM: 101606645
Informations de publication
Date de publication:
04 Sep 2020
04 Sep 2020
Historique:
received:
27
03
2020
accepted:
14
07
2020
entrez:
5
9
2020
pubmed:
6
9
2020
medline:
16
3
2021
Statut:
epublish
Résumé
Efforts to control and eliminate schistosomiasis have accelerated over the past decade. As parasite burden, associated morbidity and egg excretion decrease, diagnosis with standard parasitological methods becomes harder. We assessed the robustness and performance of a real-time PCR (qPCR) approach in comparison with urine filtration microscopy and reagent strip testing for the diagnosis of Schistosoma haematobium infections of different intensities. The robustness of DNA isolation and qPCR was validated in eight laboratories from Europe and Africa. Subsequently, 792 urine samples collected during cross-sectional surveys of the Zanzibar Elimination of Schistosomiasis Transmission (ZEST) project in 2012-2017 were examined with qPCR in 2018. Diagnostic sensitivity of the qPCR was calculated at different infection intensity categories, using urine filtration microscopy as reference test. Spearman's rank correlation between Ct-values and S. haematobium egg counts was assessed and Ct-value percentiles for infection intensity categories determined. S. haematobium Dra1 DNA-positive samples were identified correctly in all eight laboratories. Examination of urine samples from Zanzibar revealed Dra1 DNA in 26.8% (212/792) by qPCR, S. haematobium eggs in 13.3% (105/792) by urine filtration, and microhaematuria in 13.8% (109/792) by reagent strips. Sensitivity of the qPCR increased with augmenting egg counts: 80.6% (29/36) for counts between 1 and 4 eggs, 83.3% (15/18) for counts between 5 and 9 eggs, 100% (23/23) for counts between 10 and 49 eggs, and 96.4% (27/28) for counts of 50+ eggs. There was a significant negative correlation between Ct-values and egg counts (Spearman's rho = - 0.49, P < 0.001). Seventy-five percent of the Ct-values were ≥ 33 in the egg-negative category, < 31 in the light intensity category, and < 24 in the heavy intensity category. While the sensitivity of the qPCR was ~ 80% for very light intensity infections (egg counts < 10), in general, the Dra1 based qPCR assay detected twice as many S. haematobium infections compared with classical parasitological tests. The qPCR is hence a sensitive, urine-based approach for S. haematobium diagnosis that can be used for impact assessment of schistosomiasis elimination programmes, individual diagnosis, and in improved format also for verification and certification of elimination. ISRCTN, ISRCTN48837681 . Registered 05 September 2012 - Retrospectively registered.
Sections du résumé
BACKGROUND
BACKGROUND
Efforts to control and eliminate schistosomiasis have accelerated over the past decade. As parasite burden, associated morbidity and egg excretion decrease, diagnosis with standard parasitological methods becomes harder. We assessed the robustness and performance of a real-time PCR (qPCR) approach in comparison with urine filtration microscopy and reagent strip testing for the diagnosis of Schistosoma haematobium infections of different intensities.
METHODS
METHODS
The robustness of DNA isolation and qPCR was validated in eight laboratories from Europe and Africa. Subsequently, 792 urine samples collected during cross-sectional surveys of the Zanzibar Elimination of Schistosomiasis Transmission (ZEST) project in 2012-2017 were examined with qPCR in 2018. Diagnostic sensitivity of the qPCR was calculated at different infection intensity categories, using urine filtration microscopy as reference test. Spearman's rank correlation between Ct-values and S. haematobium egg counts was assessed and Ct-value percentiles for infection intensity categories determined.
RESULTS
RESULTS
S. haematobium Dra1 DNA-positive samples were identified correctly in all eight laboratories. Examination of urine samples from Zanzibar revealed Dra1 DNA in 26.8% (212/792) by qPCR, S. haematobium eggs in 13.3% (105/792) by urine filtration, and microhaematuria in 13.8% (109/792) by reagent strips. Sensitivity of the qPCR increased with augmenting egg counts: 80.6% (29/36) for counts between 1 and 4 eggs, 83.3% (15/18) for counts between 5 and 9 eggs, 100% (23/23) for counts between 10 and 49 eggs, and 96.4% (27/28) for counts of 50+ eggs. There was a significant negative correlation between Ct-values and egg counts (Spearman's rho = - 0.49, P < 0.001). Seventy-five percent of the Ct-values were ≥ 33 in the egg-negative category, < 31 in the light intensity category, and < 24 in the heavy intensity category.
CONCLUSIONS
CONCLUSIONS
While the sensitivity of the qPCR was ~ 80% for very light intensity infections (egg counts < 10), in general, the Dra1 based qPCR assay detected twice as many S. haematobium infections compared with classical parasitological tests. The qPCR is hence a sensitive, urine-based approach for S. haematobium diagnosis that can be used for impact assessment of schistosomiasis elimination programmes, individual diagnosis, and in improved format also for verification and certification of elimination.
TRIAL REGISTRATION
BACKGROUND
ISRCTN, ISRCTN48837681 . Registered 05 September 2012 - Retrospectively registered.
Identifiants
pubmed: 32887642
doi: 10.1186/s40249-020-00726-y
pii: 10.1186/s40249-020-00726-y
pmc: PMC7487541
doi:
Substances chimiques
DNA, Helminth
0
Reagent Strips
0
Types de publication
Clinical Trial
Comparative Study
Journal Article
Multicenter Study
Langues
eng
Sous-ensembles de citation
IM
Pagination
128Subventions
Organisme : Innosuisse - Schweizerische Agentur für Innovationsförderung
ID : 18553.2 PFLS-LS
Organisme : University of Georgia Research Foundation
ID : RR374-053/4893206
Organisme : University of Georgia Research Foundation
ID : RR374-053/4893196
Organisme : Bill and Melinda Gates Foundation
ID : OPP1191423
Organisme : Wellcome Trust
ID : SCAN Project 104958/Z/14/Z
Pays : United Kingdom
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