Strongyloides stercoralis
Strongyloides stercoralis is a soil-transmitted helminth affecting an estimated 300-600 million people globally. Similar to the other STHs, its transmission involves a sequence of events starting with open defecation by infected individuals, maturation of worm stages in the environment, and the presence of infectious stages of the worm in the soil. Mainly Infection occurs through skin penetration of infective larvae.
S. stercoralis is prevalent in areas with inadequate access to water, sanitation and poor hygiene, including parts of South-East Asia, Africa, Western Pacific regions, and South and Central America. Clinically, the infection can range from subclinical to severe disease manifestations, mostly involving skin, intestine, respiratory tract. A deadly complication, hyperinfection or dissemination, can occur in immunosuppressed people.
The World Health Organization (WHO) recommends implementing preventive chemotherapy (PC) programs in endemic areas with a prevalence of 5% or higher in a school-based survey or 10% in a community-based survey (measured either with Baermann or agar plate culture from stool specimens). Annually a single dose of 200 µg/kg of ivermectin is administered to both school-age children and adults living in endemic areas. Re-assessment of prevalence to evaluate continuation of drug distribution is recommended after a 5 year-period. The Baermann method and agar plate culture (APC) demonstrated the highest sensitivity for the detecting S. stercoralis compared to Kato-Katz. However, both methods require fresh stool samples, more than 24 hours between the pre-analytic phase and reading, and skilled microscopists trained specifically to recognize S. stercoralis larvae.
Therefore, there is a need for in vitro/ex vivo laboratory-based (minimum) or point-of-sampling tests (ideal) that allow for the detection of analytes specific to Strongyloides in all age groups. These tests will support reliable decisions on whether S. stercoralis programs based on mass drug administration should be implemented.
The World Health Organization (WHO) is seeking feedback on the TPP from experts in the industry, product developers, the scientific community, NTD programme personnel and clinicians currently involved in the management and control of S.stercoralis
Details of the TPP may be found in the linked document.
- Target Product Profile (Context and background)
- Draft Target Product Profile
Proposed revisions arising from the public consultation will be considered by the TPP working group before it is finalized. The final TPPs will be used for the development of diagnostics that will facilitate implementation of S.stercoralis programs .
If you have any comments, please mention them in the subject line- S.stercoralis diagnostics TPP feedback, and submit them to Dr. Denise Mupfasoni at mupfasonid@who.int.