Communication piece: Commercially available diagnostic tests

04 Dec 2020
GSA Diagnostic workstream

The Global Schistosomiasis Alliance (GSA)* Diagnostic Work Stream has gathered information on commercially available diagnostic tests for schistosomiasis. This is a working document that will be reviewed and updated as new diagnostics become available. You can download the list in English here. A French and Spanish version will be available soon.

If you would like to send any schistosomiasis diagnostic information to the group you can contact the GSA anouk [dot] gouvras [at] eliminateschisto [dot] org (subject: Schistosomiasis%20Diagnostics) (by clicking here.)

Summary

Schistosomiasis affects over 200 million people worldwide[1], and more than 700 million people in endemic areas are at risk of infection[2], being one of the most prevalent of the Neglected Tropical Diseases (NTDs). It also accounts for an estimated 1.9 million disability-adjusted life years (DALYs) annually2. Several million people all over the world suffer from severe morbidity as a consequence of schistosomiasis[3].

In 2012, World Health Assembly Resolution 65.21 called on countries to intensify control and initiate elimination campaigns where feasible. In the same year, the WHO defined control of morbidity as <5% prevalence of heavy intensity infection in school-aged children, and elimination as a public health problem as <1% prevalence of heavy intensity infection in school-aged children.

National NTD programmes and collaborating partners need to track progress towards reaching the WHO NTD Roadmap goals. Each country has a strategic or masterplan with specific objectives and actions to reach the control and elimination goals and to measure achievements through specific coverage and infection indicators.          

Both infection prevalence and intensity are key indicators used by countries to monitor and evaluate interventions and to track progress towards control or elimination of the disease. Countries require sensitive diagnostic tools that are affordable and can be used in low-resource settings. It is therefore vital to gather information about currently available diagnostic tests. First, in order to know which tools are available and in which context they can be used, so that national programmes can have the right diagnostic tool for achieving their targets. Secondly, to identify the diagnostic gaps and requirements for schistosomiasis programmes moving from disease control to elimination as a public health problem, and for schistosomiasis surveillance post-transmission interruption. Finally, there is a need for further standardization of diagnostics tests and their output, in order to increase transparency of collected data and improve comparability of surveys or the outcome of different intervention programs.

The Global Schistosomiasis Alliance (GSA)* Diagnostic Work Stream has gathered information on commercially available diagnostic tests for schistosomiasis in order to make this information accessible to Ministries of Health, policy makers, schistosomiasis researchers and other stakeholders. The focus is on schistosome endemic regions, but the outcome is also likely to facilitate decisions about how to improve the diagnostic workflow for imported schistosomiasis cases in non-endemic settings. The best diagnostic tool will depend on different factors, such as the setting where it is going to be used, the species of Schistosoma to be detected, and the goal or strategy of the programme. Higher sensitivity and specificity will be needed when moving towards elimination goals, or when diagnosing returning travellers in non-endemic areas, typically showing low intensity infections. However, when the aim is to reach morbidity control, the focus would probably be on ease-of-use and low cost to be used as a Point-Of-Care / Point-Of-Need test. In this case, an ideal diagnostic test would follow the WHO ASSURED criteria (Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free and Deliverable to end-users)[4].

The following tables (table 1a, 1b and 1c) list currently commercially available diagnostics. Not all are recommended by WHO nor GSAa. The diagnostic methods that are currently recommended by WHO are the microscopy methods – Kato-Katz (KK) on faecal samples for the diagnosis of intestinal schistosomiasis, and Urine Filtration (UF) for urogenital schistosomiasis[5]. These methods, although specific, lack sensitivity. In addition, in S. mansoni transmission areas, WHO also recommends the Point-of-Care test based on circulating cathodic antigen (POC-CCA) detection[6]. While schistosome circulating antigens reflect the presence of viable worms (current infection), specific antibodies cannot distinguish past and/or present infections. Consequently, antibody detection tests are not suitable for identifying current infections.

The GSA Diagnostic Work Stream hopes to update this list as new diagnostics become available. Please contact anouk [dot] gouvras [at] eliminateschisto [dot] org (subject: Schistosomiasis%20Diagnostics) (the GSA office) for comments, updates or additional information. 

*Global Schistosomiasis Alliance

The Global Schistosomiasis Alliance (GSA) is a coalition whose objective is to bring together the different actors needed to advance in the control and elimination of schistosomiasis. It is constituted as a diverse but representative partnership of endemic countries, academic and research institutions, international development agencies and foundations, international organizations, non-governmental development organizations, private sector companies and advocacy and resource mobilizations partners.

a The tables in the document are not a list of recommended tests or a list of tests to be used by stakeholders, this is only an information piece collating what is currently commercially available. Manufacturers should be contacted to find out intended and appropriate use as well as details on methodology, logistics, cost and safety. As diagnostic test properties are dependent on locally performed procedures and endemicity characteristics, it is important to follow diagnostic protocols as indicated by the provider and also to perform proper test verification in your own settings. Where appropriate, participation in an external quality assessment scheme is recommended.

This information was collected by consulting a number of stakeholders and reaching out to manufacturers for more information. Where information is missing this is because this was not easily available and/or the manufactures did not respond to requests for more information. The GSA and its members and partners take no responsibility for any incorrect information or inadequate or negative outcome from the use of these diagnostics tests.

References

 

[1] WHO Schistosomiasis and soil-transmitted helminthiases: number of people treated in 2018. Wkly Epidemiol Rec. 2019; 50: 601–612.s

[2] Abajobir et al. Global, regional, and national disability-adjusted life-years (DALYs) for 333 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet. 2017;390: 1260–1344.

[3] WHO Key Facts on Schistosomiasis: https://www.who.int/en/news-room/fact-sheets/detail/schistosomiasis

[4] Mabey et al. Diagnostics for the developing world. Nature Reviews Microbiology 2004; 2: 231–240.

[5] Bench aids for the diagnosis of intestinal parasites, second edition. Geneve: World Health Organization;
2019. License: CC BY-NC-SA 3.0 IGO

[6] Bärenbold O, Garba A, Colley DG, Fleming FM, Haggag AA, Ramzy RMR, et al. (2018) Translating preventive chemotherapy prevalence thresholds for Schistosoma mansoni from the Kato-Katz technique into the point-of-care circulating cathodic antigen diagnostic test. PLoS Negl Trop Dis 12(12): e0006941. https://doi.org/10.1371/journal.pntd.0006941

Monitoring and Evaluation Research GSA