A rapid test using a single drop of blood to screen for schistosomiasis in non-endemic countries
Authors: Zeno Bisoffi, Stefania Varani, Bianca Granozzi, Silvia Stefania Longoni, Margherita Ortalli
Journal: The Lancet Microbe (2024)

The systematic review and meta-analysis by Michel T Vaillant and colleagues1Vaillant MT Philippy F Neven A et al.Diagnostic tests for human Schistosoma mansoni and Schistosoma haematobium infection: a systematic review and meta-analysis.Lancet Microbe. 2024; 5: e366-e378Summary Full Text Full Text PDF Scopus (0) Google Scholar represents a major advance in understanding the performance of the main diagnostic tests for schistosomiasis in endemic regions. However, schistosomiasis has posed a major public health problem in non-endemic countries as well, owing to migration, particularly from sub-Saharan Africa. The estimated prevalence of this disease is higher than 50% in some national groups,2Beltrame A Buonfrate D Gobbi F et al.The hidden epidemic of schistosomiasis in recent African immigrants and asylum seekers to Italy.Eur J Epidemiol. 2017; 32: 733-735Crossref PubMed Scopus (39) Google Scholar making the need for screening a public health priority, as also indicated by European and Italian guidelines.3European Centre for Disease Prevention and ControlPublic health guidance on screening and vaccination of migrants in the EU EEA.https://www.ecdc.europa.eu/en/publications-data/public-health-guidance-screening-and-vaccination-infectious-diseases-newlyDate: 2018Date accessed: March 19, 2024Google Scholar,4Comelli A Genovese C Gobbi F et al.Schistosomiasis in non-endemic areas: Italian consensus recommendations for screening, diagnosis and management by the Italian Society of Tropical Medicine and Global Health (SIMET), endorsed by the Committee for the Study of Parasitology of the Italian Association of Clinical Microbiologists (CoSP-AMCLI), the Italian Society of Parasitology (SoIPa), the Italian Society of Gastroenterology and Digestive Endoscopy (SIGE), the Italian Society of Gynaecology and Obstetrics (SIGO), the Italian Society of Colposcopy and Cervico-Vaginal Pathology (SICPCV), the Italian Society of General Medicine and Primary Care (SIMG), the Italian Society of Infectious and Tropical Diseases (SIMIT), the Italian Society of Pediatrics (SIP), the Italian Society of Paediatric Infectious Diseases (SITIP), the Italian Society of Urology (SIU).Infection. 2023; 51: 1249-1271PubMed Google Scholar Unfortunately, the test with the optimal balance of sensitivity and specificity for Schistosoma mansoni according to the meta-analysis by Vaillant and colleagues,1Vaillant MT Philippy F Neven A et al.Diagnostic tests for human Schistosoma mansoni and Schistosoma haematobium infection: a systematic review and meta-analysis.Lancet Microbe. 2024; 5: e366-e378Summary Full Text Full Text PDF Scopus (0) Google Scholar circulating cathodic antigen in urine, showed poor performance in non-endemic areas.5Beltrame A Guerriero M Angheben A et al.Accuracy of parasitological and immunological tests for the screening of human schistosomiasis in immigrants and refugees from African countries: an approach with latent class analysis.PLoS Negl Trop Dis. 2017; 11e0005593Crossref Scopus (70) Google Scholar In these areas, the aim is to primarily offer serological screening to people from endemic countries and treat positive cases by prioritising sensitivity over specificity, considering the risk of untreated infection and the fact that treatment of chronic schistosomiasis with praziquantel is highly effective and well tolerated.3European Centre for Disease Prevention and ControlPublic health guidance on screening and vaccination of migrants in the EU EEA.https://www.ecdc.europa.eu/en/publications-data/public-health-guidance-screening-and-vaccination-infectious-diseases-newlyDate: 2018Date accessed: March 19, 2024Google Scholar,4Comelli A Genovese C Gobbi F et al.Schistosomiasis in non-endemic areas: Italian consensus recommendations for screening, diagnosis and management by the Italian Society of Tropical Medicine and Global Health (SIMET), endorsed by the Committee for the Study of Parasitology of the Italian Association of Clinical Microbiologists (CoSP-AMCLI), the Italian Society of Parasitology (SoIPa), the Italian Society of Gastroenterology and Digestive Endoscopy (SIGE), the Italian Society of Gynaecology and Obstetrics (SIGO), the Italian Society of Colposcopy and Cervico-Vaginal Pathology (SICPCV), the Italian Society of General Medicine and Primary Care (SIMG), the Italian Society of Infectious and Tropical Diseases (SIMIT), the Italian Society of Pediatrics (SIP), the Italian Society of Paediatric Infectious Diseases (SITIP), the Italian Society of Urology (SIU).Infection. 2023; 51: 1249-1271PubMed Google Scholar We have recently completed a prospective diagnostic study on a rapid immunochromatographic test (ICT) that allows the detection of specific antibodies directly on drops of blood obtained through a fingerprick. This test, currently in the clinical validation phase, is a modified version of the SCHISTOSOMA ICT IgG-IgM kit (LDBIO Diagnostics, Lyon, France), which is used with serum samples only. Once shown to be accurate, the new test would have an obvious advantage over its predecessor and over all currently available serological tests, as this test would eliminate the need for a laboratory and allow for decentralised screening. Preliminary data are encouraging. In an analysis of 198 individuals from endemic areas who were tested consecutively, the new test showed a sensitivity of 100% and specificity of 63% (95% CI 56–70) according to the primary reference standard (presence of eggs in faeces or urine). When a composite reference standard (defined by at least two positive tests of three among ELISA, SCHISTOSOMA ICT IgG-IgM, and western blotting) was considered, the sensitivity of the new test was 86% (95% CI 81–91) and the specificity was 88% (95% CI 83–92). Data analysis with Bayesian latent class analysis is ongoing, and the results will be published as soon as possible. Nevertheless, the preliminary data indicate that a test might soon be available, which could be performed after a simple fingerprick, could provide results within 20 min, and could contribute to effective schistosomiasis screening and treatment of populations at risk in non-endemic areas. We declare no competing interests. ZB and SSL were partially supported by the Italian Ministry of Health, "Fondi Ricerca Corrente, project L3P2".