WHO guideline on preventive chemotherapy for public health control of strongyloidiasis 

Human strongyloidiasis is a chronic parasitic disease caused by infection with Strongyloides stercoralis, a soil-transmitted helminth that is estimated to infect 300–600 million people worldwide. This neglected tropical disease (NTD) is endemic globally, predominately in the South-East Asia, African and Western Pacific regions, and in South and Central America. Strongyloidiasis has a wide range of clinical presentations, including subclinical disease, symptomatic disease (often with diarrhoea, abdominal pain and urticaria) and a rare but deadly complication of hyperinfection with disseminated disease. The feared complication of disseminated strongyloidiasis can occur in the setting of immunocompromising conditions (e.g. human T-cell lymphotropic virus type 1 infection and malignancies) or immunosuppressive medications (e.g. steroids) and has an estimated case-fatality rate exceeding 60%. The standard treatment for chronic S. stercoralis infection is oral medication with ivermectin.

The objective of this WHO guideline is aligned with that of Sustainable Development Goal 3: to “ensure healthy lives and promote well-being for all at all ages” and the World Health Assembly resolution to expand access to prevention, diagnosis, treatment and care interventions for NTDs as a contribution towards the achievement of universal health coverage by 2030.

Its goal is to provide an evidence-informed recommendation on whether preventive chemotherapy with ivermectin as a public health intervention to reduce the disease burden caused by strongyloidiasis should:

• be implemented as a programme targeting both adults and school-aged children (i.e. MDA) in endemic settings that are above a defined prevalence threshold of strongyloidiasis;
• be implemented as a school-based programme alone (i.e. targeted preventive chemotherapy) in endemic settings that are above a defined prevalence threshold of strongyloidiasis; or
• not be implemented through preventive chemotherapy and instead be given following standard clinical care of individual cases.

This public health guideline recommendation is not intended to replace any standard of care for treatment of clinical strongyloidiasis. No public health approach replaces the need for timely diagnosis and treatment for strongyloidiasis through accessible health care.