The World Health Organization (WHO) recommends preventive chemotherapy (PC) as the primary intervention to control morbidity of soil-transmitted helminthiasis (STH). In this series of maps we present the impact of the intervention on the prevalence of STH. The STH prevalence in countries that after 5 years of intervention conducted impact survey is presented in different shades of brown (
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The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted and dashed lines on maps represent approximate border lines for which there may not yet be full agreement. The borders of the map provided reflect the current political geographic status as of the date of publication (2021). However, the technical health information is based on data accurate with respect to the year indicated (2020). The disconnect in this arrangement should be noted but no implications regarding political or terminological status should be drawn from this arrangement as it is purely a function of technical and graphical limitations.

Impact of intervention on STH prevalence
Region <2% ≥2%  <10% ≥10%  <20% ≥20%  <50% ≥50% Evaluation not done/ results of evaluation not available No data
Africa (AFRO) Burkina Faso, Ghana*, Mali, Niger, Zimbabwe Cabo Verde, Cote D’Ivoire, Kenya, Senegal, Sierra Leone, Tanzania* Benin, Burundi, Cameroon, Liberia, Togo Ethiopia, Rwanda Comoros Botswana, Central African Republic, Chad, Congo, Democratic Republic of the Congo, Gabon, Gambia, Guinea, Guinea-Bissau, Lesotho, Madagascar, Malawi, Mozambique, Sao Tome and Principe, South Africa, South Sudan, Swaziland, Uganda, Zambia Angola, Equatorial Guinea, Nigeria
Americas (PAHO)   Brazil, Dominican Republic       Colombia, El Salvador, Guatemala, Guyana, Haiti, Honduras, Mexico, Nicaragua, Venezuela, Paraguay Bolivia, Ecuador, Perù
South-East Asia (SEARO)  Bhutan, Nepal* Indonesia Bangladesh, Timor-Leste Democratic Peoples Republic of Korea, Myanmar   India**  
Europe (EURO)            Kyrgyzstan Tajkistan, Uzbekistan
Eastern Mediterranean (EMRO) Sudan         Afghanistan, Iraq, Pakistan, Syria, Somalia Djibouti, Yemen
Western Pacific (WPRO)      Cambodia, Lao, Vietnam Philippines*   Fiji, Kiribati, Marshall Islands, Papua New Guinea, Tuvalu Micronesia, Solomon Islands, Tonga, Vanuatu
Total of countries 8 9 10 5 1 41 14

* partial data, not from a national survey

** large country with regions showing different progresses in implementation and impacts

Laboratory of Parasitology and Parasitic Diseases
Department of Veterinary Medicine and Animal Production
University of Naples Federico II


Prof. Laura Rinaldi
phone: +39 081 2536281
Prof. Giuseppe Cringoli
phone: +39 081 2536283
Prof. Maria Paola Maurelli
phone: +39 081 2536014
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