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Redefining typhoid diagnosis: what would an improved test need to look like?
  1. Richard G Mather1,2,
  2. Heidi Hopkins2,
  3. Christopher M Parry3,4,
  4. Sabine Dittrich1,5
  1. 1Malaria and Fever Program, Foundation for Innovative New Diagnostics (FIND), Geneva, Switzerland
  2. 2Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
  3. 3Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
  4. 4School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
  5. 5Nuffield Department of Medicine, University of Oxford, Oxford, UK
  1. Correspondence to Dr Sabine Dittrich; sabine.dittrich{at}finddx.org

Abstract

Introduction Typhoid fever is one of the most common bacterial causes of acute febrile illness in the developing world, with an estimated 10.9 million new cases and 116.8 thousand deaths in 2017. Typhoid point-of-care (POC) diagnostic tests are widely used but have poor sensitivity and specificity, resulting in antibiotic overuse that has led to the emergence and spread of multidrug-resistant strains. With recent advances in typhoid surveillance and detection, this is the ideal time to produce a target product profile (TPP) that guides product development and ensure that a next-generation test meets the needs of users in the resource-limited settings where typhoid is endemic.

Methods A structured literature review was conducted to develop a draft TPP for a next-generation typhoid diagnostic test with minimal and optimal desired characteristics for 36 test parameters. The TPP was refined using feedback collected from a Delphi survey of key stakeholders in clinical medicine, microbiology, diagnostics and public and global health.

Results A next-generation typhoid diagnostic test should improve patient management through the diagnosis and treatment of infection with acute Salmonella enterica serovars Typhi or Paratyphi with a sensitivity ≥90% and specificity ≥95%. The test would ideally be used at the lowest level of the healthcare system in settings without a reliable power or water supply and provide results in <15 min at a cost of <US$1.00.

Conclusion This report outlines the first comprehensive TPP for typhoid fever and is intended to guide the development of a next-generation typhoid diagnostic test. An accurate POC test will reduce the morbidity and mortality of typhoid fever through rapid diagnosis and treatment and will have the greatest impact in reducing antimicrobial resistance if it is combined with diagnostics for other causes of acute febrile illness in a treatment algorithm.

  • diagnostics and tools
  • typhoid and paratyphoid fevers
  • Other diagnostic or tool
  • Public Health

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Footnotes

  • Handling editor Seye Abimbola

  • Contributors RGM, HH and SD contributed to the initial study design including the literature review and development of the draft TPP. CMP provided foundational work that formed part of the draft TPP. RGM and SD conducted the Delphi survey. CMP participated in the Delphi survey and provided key comments for shaping the final TPP. The manuscript was conceived and written by RGM and SD with input from HH and CMP. All authors participated in revising the manuscript and approved the final version.

  • Funding This study was funded by Department for International Development (http://dx.doi.org/10.13039/501100000278).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.

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