Meeting Report: WHO Diagnostic Technical Advisory Group for Neglected Tropical Diseases

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The WHO Department of Control of Neglected Tropical Diseases manages a diverse portfolio of 20 disease categories, each with its own unique epidemiological and diagnostic challenges. Programmes to address each of these diseases have different goals according to the targets set for a particular disease: control, elimination as a public health problem, elimination of transmission, or eradication. These programmatic goals may also change over time as programmes achieve success and disease prevalence declines, as new tools are developed or as global attention attracts increased support and commitment. Accurate and reliable diagnostic tools are necessary for all of these programmes. While classical clinical and parasitological techniques are often adequate for mapping the distribution of disease and monitoring the progress of interventions against neglected tropical diseases (NTDs), the need for improved diagnostics becomes critical as infection prevalence declines and elimination becomes a possibility.

For NTDs that require case management, diagnostics are essential to achieve the goals of control, elimination or eradication, as the intervention for this group of diseases relies on detecting individual cases and conducting surveillance. The addition of new diseases to the portfolio has highlighted the requirement for improved diagnostic tools. For diseases targeted by preventive chemotherapy, diagnostic tests are required to support programmatic decisions on changing the frequency of treatment or stopping mass treatment, or on conducting surveillance and validating or verifying elimination. Reports from the field indicate that NTD programmes are facing a number of problems that require urgent solutions. Recognition of the achievements accomplished on the road to 2020, and the enthusiasm generated by the Sustainable Development Goals for 2030, have renewed momentum for consolidating programme gains and accelerating progress towards programme end-points, as reflected in the new road map, which identifies critical gaps in diagnostics in order to meet the ambitious targets for 2030.

In view of the need to support programmes to deliver much-needed health interventions to vulnerable populations, and in order to demonstrate and maintain the health gains achieved so far, the Department has determined, in accordance with the recommendations of the Strategic and Technical Advisory Group for Neglected Tropical Diseases, that it is necessary to reassess needs and access-related issues around diagnostics for all the diseases in its portfolio.

Despite the diversity of the programme goals, common areas exist across programmes that lend themselves well to consideration by a single working group for diagnostics. Individual programmes, depending on their goals, may need diagnostics for case detection, diagnosis, prognosis, mapping of endemicity, monitoring and evaluation, test of cure and whether to stop mass treatment, determination of infectivity and/or post-treatment surveillance. A single WHO working group will ensure a unified approach to identifying and prioritizing diagnostic needs and to informing WHO strategies and guidance on the subject.

In accordance, the objectives of the first meeting of the DTAG were:

• to review the terms of reference, structure and working modalities of the group;
• to introduce the WHO process for developing target product profiles (TPPs) development and including TPPs in the WHO Model List of Essential In Vitro Diagnostics; and
• to discuss critical gaps in and prioritization of NTD diagnostics and the use cases for these tools."