• Cryptococcal antigen screening by lay cadres using a rapid test at the point of care: A feasibility study in rural Lesotho

      Rick, F; Niyibizi, AA; Shroufi, A; Onami, K; Steele, SJ; Kuleile, M; Muleya, I; Chiller, T; Walker, T; Van Cutsem, G (Public Library of Science, 2017-09-06)
      Cryptococcal meningitis is one of the leading causes of death among people with HIV in Africa, primarily due to delayed presentation, poor availability and high cost of treatment. Routine cryptococcal antigen (CrAg) screening of patients with a CD4 count less than 100 cells/mm3, followed by pre-emptive therapy if positive, might reduce mortality in high prevalence settings. Using the cryptococcal antigen (CrAg) lateral flow assay (LFA), screening is possible at the point of care (POC). However, critical shortages of health staff may limit adoption. This study investigates the feasibility of lay counsellors conducting CrAg LFA screening in rural primary care clinics in Lesotho.
    • Evaluation of a Rapid Test for the Diagnosis of Cholera in the Absence of a Gold Standard

      Page, Anne-Laure; Alberti, Kathryn P.; Mondonge, Vital; Rauzier, Jean; Quilici, Marie-Laure; Guerin, Philippe J.; Bhutta, Zulfiqar A.; Epicentre, Paris, France; Ministry of Health, Kinshasa, Democratic Republic of Congo; Institut Pasteur, Unité des Bactéries Pathogènes Entériques, Centre National de Référence des Vibrions et du Choléra, Paris, France; Nuffield Department of Clinical Medicine, Centre for Tropical Medicine, Centre for Clinical Vaccinology and Tropical Medicine (CCVTM), University of Oxford, Oxford, United Kingdom (Public Library of Science, 2012-05-30)
      Early detection and confirmation of cholera outbreaks are crucial for rapid implementation of control measures. Because cholera frequently affects regions with limited laboratory resources, rapid diagnostic tests (RDT) designed for field conditions are important to enhance rapid response. Stool culture remains the ‘‘gold standard’’ for cholera diagnosis; however, its lack of sensitivity may lead to underestimation of test specificity. We evaluated the Crystal VCH immunochromatographic test (Span Diagnostics, India) for cholera diagnosis using a modified reference standard that combines culture-dependent and independent assays, or a Bayesian latent class model (LCM) analysis. The study was conducted during a cholera epidemic in 2008, in Lubumbashi, Democratic Republic of Congo. Stools collected from 296 patients were used to perform the RDT on site and sent to Institut Pasteur, Paris, for bacterial culture. In comparison with culture as the gold standard, the RDT showed good sensitivity (92.2%; 95% CI: 86.8%–95.9%) but poor specificity when used by a trained laboratory technician (70.6%; 95% CI: 60.7%–79.2%) or by clinicians with no specific test training (60.4%, 95% CI: 50.2%–70.0%). The specificity of the test performed by the laboratory technician increased to 88.6% (95% CI: 78.7–94.9) when PCR was combined with culture results as the reference standard, and to 85.0% (95% CI: 70.4–99.2), when the Bayesian LCM analysis was used for performance evaluation. In both cases, the sensitivity remained high. Using an improved reference standard or appropriate statistical methods for diagnostic test evaluations in the absence of a gold standard, we report better performance of the Crystal VCH RDT than previously published. Our results confirm that this test can be used for early outbreak detection or epidemiological surveillance, key components of efficient global cholera control. Our analysis also highlights the importance of improving evaluations of RDT when no reliable gold standard is available.
    • Identifying the snake: First scoping review on practices of communities and healthcare providers confronted with snakebite across the world

      Bolon, I; Durso, A; Botero Mesa, S; Ray, N; Alcoba, G; Chappuis, F; Ruiz de Castañeda, R (Public Library of Science, 2020-03-05)
      BACKGROUND: Snakebite envenoming is a major global health problem that kills or disables half a million people in the world's poorest countries. Biting snake identification is key to understanding snakebite eco-epidemiology and optimizing its clinical management. The role of snakebite victims and healthcare providers in biting snake identification has not been studied globally. OBJECTIVE: This scoping review aims to identify and characterize the practices in biting snake identification across the globe. METHODS: Epidemiological studies of snakebite in humans that provide information on biting snake identification were systematically searched in Web of Science and Pubmed from inception to 2nd February 2019. This search was further extended by snowball search, hand searching literature reviews, and using Google Scholar. Two independent reviewers screened publications and charted the data. RESULTS: We analysed 150 publications reporting 33,827 snakebite cases across 35 countries. On average 70% of victims/bystanders spotted the snake responsible for the bite and 38% captured/killed it and brought it to the healthcare facility. This practice occurred in 30 countries with both fast-moving, active-foraging as well as more secretive snake species. Methods for identifying biting snakes included snake body examination, victim/bystander biting snake description, interpretation of clinical features, and laboratory tests. In nine publications, a picture of the biting snake was taken and examined by snake experts. Snakes were identified at the species/genus level in only 18,065/33,827 (53%) snakebite cases. 106 misidentifications led to inadequate victim management. The 8,885 biting snakes captured and identified were from 149 species including 71 (48%) non-venomous species. CONCLUSION: Snakebite victims and healthcare providers can play a central role in biting snake identification and novel approaches (e.g. photographing the snake, crowdsourcing) could help increase biting snake taxonomy collection to better understand snake ecology and snakebite epidemiology and ultimately improve snakebite management.