Sensitivity and specificity of human point-of-care circulating cathodic antigen (POC-CCA) test in African livestock for rapid diagnosis of schistosomiasis: A Bayesian latent class analysis

Beatriz Calvo-Urbano; Elsa Léger; Isobel Gabain; Claudia J De Dood; Nicolas D Diouf; Anna Borlase; James W Rudge; Paul L A M Corstjens; Mariama Sène; Govert J Van Dam; Martin Walker; Joanne P Webster

doi:10.1371/journal.pntd.0010739

Sensitivity and specificity of human point-of-care circulating cathodic antigen (POC-CCA) test in African livestock for rapid diagnosis of schistosomiasis: A Bayesian latent class analysis

PLoS Negl Trop Dis. 2023 May 22;17(5):e0010739. doi: 10.1371/journal.pntd.0010739. eCollection 2023 May.

Authors

Beatriz Calvo-Urbano^{1

2}, Elsa Léger^{1

2}, Isobel Gabain^{1

2}, Claudia J De Dood³, Nicolas D Diouf⁴, Anna Borlase^{1

5}, James W Rudge^{2

6

7}, Paul L A M Corstjens³, Mariama Sène⁴, Govert J Van Dam³, Martin Walker^{1

2}, Joanne P Webster^{1

2}

Affiliations

¹ Royal Veterinary College, Department of Pathobiology and Population Sciences, University of London, Hatfield, United Kingdom.
² London Centre for Neglected Tropical Disease Research, School of Public Health, Department of Infectious Disease Epidemiology, Imperial College Faculty of Medicine, London, United Kingdom.
³ Leiden University Medical Centre, Leiden, The Netherlands.
⁴ Unité de Formation et de Recherche des Sciences Agronomiques, d'Aquaculture et de Technologies Alimentaires, Université Gaston Berger, Saint Louis, Senegal.
⁵ Department of Biology, University of Oxford, Oxford, United Kingdom.
⁶ Communicable Diseases Policy Research Group, Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, United Kingdom.
⁷ Faculty of Public Health, Mahidol University, Bangkok, Thailand.

Abstract

Schistosomiasis is a major neglected tropical disease (NTD) affecting both humans and animals. The morbidity and mortality inflicted upon livestock in the Afrotropical region has been largely overlooked, in part due to a lack of validated sensitive and specific tests, which do not require specialist training or equipment to deliver and interpret. As stressed within the recent WHO NTD 2021-2030 Roadmap and Revised Guideline for schistosomiasis, inexpensive, non-invasive, and sensitive diagnostic tests for livestock-use would also facilitate both prevalence mapping and appropriate intervention programmes. The aim of this study was to assess the sensitivity and specificity of the currently available point-of-care circulating cathodic antigen test (POC-CCA), designed for Schistosoma mansoni detection in humans, for the detection of intestinal livestock schistosomiasis caused by Schistosoma bovis and Schistosoma curassoni. POC-CCA, together with the circulating anodic antigen (CAA) test, miracidial hatching technique (MHT), Kato-Katz (KK) and organ and mesentery inspection (for animals from abattoirs only), were applied to samples collected from 195 animals (56 cattle and 139 small ruminants (goats and sheep) from abattoirs and living populations) from Senegal. POC-CCA sensitivity was greater in the S. curassoni-dominated Barkedji livestock, both for cattle (median 81%; 95% credible interval (CrI): 55%-98%) and small ruminants (49%; CrI: 29%-87%), than in the S. bovis-dominated Richard Toll ruminants (cattle: 62%; CrI: 41%-84%; small ruminants: 12%, CrI: 1%-37%). Overall, sensitivity was greater in cattle than in small ruminants. Small ruminants POC-CCA specificity was similar in both locations (91%; CrI: 77%-99%), whilst cattle POC-CCA specificity could not be assessed owing to the low number of uninfected cattle surveyed. Our results indicate that, whilst the current POC-CCA does represent a potential diagnostic tool for cattle and possibly for predominantly S. curassoni-infected livestock, future work is needed to develop parasite- and/or livestock-specific affordable and field-applicable diagnostic tests to enable determination of the true extent of livestock schistosomiasis.

Copyright: © 2023 Calvo-Urbano et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

MeSH terms

Animals
Antigens, Helminth
Bayes Theorem
Cattle
Feces / chemistry
Humans
Latent Class Analysis
Livestock*
Point-of-Care Systems
Prevalence
Schistosoma mansoni
Schistosomiasis mansoni* / epidemiology
Sensitivity and Specificity
Sheep

Substances

Antigens, Helminth

Grants and funding

This research was funded by the Biotechnology and Biological Sciences Research Council, the Department for International Development, the Economic & Social Research Council, the Medical Research Council, the Natural Environment Research Council and the Defence Science & Technology Laboratory, under the Zoonoses and Emerging Livestock Systems (ZELS:SR) programme (grant numbers BB/L018985/1: ‘SHEEP’ – Schistosoma Hybridization Evolution, Epidemiology and Prevention) PI: JPW, co-I within Senegal: MS) and BB/S013822/1: ‘CATTLES - Control And Targeted Treatment for Livestock Emerging Schistosomiasis’); PI: JPW, co-I MW, co-Is within Senegal: MS and ND), and Research England grants: The Bloomsbury SET project grants (grant number CCF-17-7779; PI: JPW, co-Is MW and EL and 8JW-RVC; NRG55989: PI: JPW, co-Is BC-U and MW). The funders played no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.