Schistosomiasis
Schistosomiasis is a parasitic disease that affects almost 240 million people globally, with more than 700 million living in endemic areas. Infection occurs when people come into contact with contaminated water populated with the appropriate intermediate host snail. Larval parasites penetrate the skin and enter the body where they mature into adult male and female worms, mate, and produce eggs. Some eggs released by adult females exit the body to continue the parasite’s life cycle, but other eggs become trapped in host tissues where they stimulate immunologic responses that cause the morbidity associated with schistosomiasis.
Soil-transmitted helminths
Soil-transmitted helminths (STH) are a group of intestinal worms, including Ascaris lumbricoides (giant roundworm), Trichuris trichiura (whipworm), Ancylostoma duodenale and Necator americanus (hookworms). Despite the clear biological differences across the different worm species, their transmission is characterized by the same sequence of events: (i) infected individuals excrete worm eggs through their stool in soil; (ii) under optimal
conditions of moisture and temperature the excreted eggs will develop into infectious stages; (iii) finally infection occurs through oral uptake (A. lumbricoides, A. duodenale and T. trichiura ) or skin penetration (A. duodenale and N. americanus) of these infectious stages (embryonated eggs and third stage larvae) that reside in the soil and/or in the environment (referring to their common name).
Currently effective tools for monitoring and evaluation of both schistosomiasis and STH control programs are available and based on egg detection in faces or urine. However cost, challenges of obtaining samples, and the need for trained personnel and equipment limit frequency of monitoring.
The purpose of the monitoring and evaluation Target Product Profiles (TPP) proposed by WHO’s Department of Control of Neglected Tropical Diseases (WHO NTD) for schistosomiasis is to guide development of new diagnostic tools to reliably measure when prevalence is above or below a cut off of 10% in school age children. The purpose of the surveillance TPP proposed by WHO NTD is to guide development of new diagnostic tools to reliably detect 3% infection prevalence.
The purpose of the M&E TPP for STH proposed by WHO NTD is to lead to development of new diagnostic tools to reliably make program decisions on whether STH programs should start PC, move towards the next phase or ultimately stop PC, based on WHO’s
decision algorithm.
The WHO is asking for feedback on all three TPPs. Feedback is invited from experts in the industry, product development, parasitologists, the scientific community, NTD programme personnel and other technicians currently implementing WHO recommended surveys.
Details of the TPPs may be found in the linked documents.
- TPP Scope Schistosomiasis Monitoring & Evaluation narrative
- TPP Scope Schistosomiasis surveillance narrative
- TPP Scope Soil-transmitted helminths Monitoring & Evaluation narrative
- SCH TPP draft Zero
- STH TPP draft Zero
Access the online form
Any proposed revisions during the public consultation will be considered by the TPP working group before finalizing it. The final TPPs will be used for the development of diagnostics to improve decisions leading to the interruption of transmission of
schistosomiasis.