Neglected tropical diseases

WHO plans major scale-up of interventions for soil-transmitted helminthiases (intestinal worms)

Objective is to secure 75% coverage of all school-age children worldwide

08 June 2012 | Geneva

Millions more pre-school and school-age children are poised to receive treatment for soil-transmitted helminthiases (also known as intestinal worms) in future large-scale preventive chemotherapy interventions.

In 2010, deworming programmes coordinated by the World Health Organization (WHO) covered a total of 328 million pre-school and school age children in treatment campaigns worldwide corresponding to 31% of the global target.

Statistics published in the recent edition of the Weekly Epidemiological Record No.23, 2012, 87:225–232 [pdf 1.2Mb] show that more than 50% of all children in need of treatment worldwide live in 5 countries - Bangladesh, China, India, Indonesia and Nigeria. Some of these countries are in the initial phase of a control programme and WHO believes it is essential that these countries start control activities in order to scale up interventions at national level before 2020.

“WHO’s control programmes benefit from robust political support in endemic countries” said Dr Lorenzo Savioli, Director of the Department of Control of Neglected Tropical Diseases. “One of our main objectives now is to strengthen capacity in these countries to support a substantial increase in interventions aimed at reaching a minimum coverage of 75% of all children”.

The scale-up is part of a renewed WHO-led global interest in (and awareness of) neglected tropical diseases, punctuated by the publication in 2010 of the first WHO Report on neglected tropical diseases and subsequently the NTD Roadmap in January 2012, setting out clear goals and targets for 2012-2020.

Major pharmaceutical companies have come forward to commit additional donations and resources to help support WHO’s plan to combat many of the 17 neglected tropical diseases, including soil-transmitted helminthiases.

“Soil-transmitted helminths are among the most common infections worldwide, affecting more than two billion people” said Dr Antonio Montresor of the Preventive Chemotherapy and Transmission Control Programme of the Department of Control of Neglected Tropical Diseases. “Children are more vulnerable as intestinal worms cause anaemia, stunted growth and severely affect health and overall wellbeing.”

Since 2006 and as part of a coordinated strategy on the use of anthelminthic medicines (albendazole and mebendazole), WHO recommended school-based treatment programmes, targeting mainly children between 5 and 14 years of age.

During preventive chemotherapy interventions, all eligible pre-school and school age children within a geographic area are given the appropriate dose of medicine to ingest. The concept is to treat, once or twice per year, all preschool and school age children. Similarly, women of child-bearing age (including pregnant women in the 2nd and 3rd trimesters and lactating women) are also treated.

Out of the 328 million children who received preventive chemotherapy for soil-transmitted helminthiases in 2010 alone, more than 275 million children were found to be in need of treatment, corresponding to 31% global coverage.

Soil-transmitted helminthiases

Soil-transmitted helminthiases (STH) are intestinal infections in humans. They are caused by four species of nematodes, collectively referred to as soil-transmitted helminths: Ascaris lumbricoides (the roundworm), Trichuris trichiura (the whipworm) and Necator americanus or Ancylostoma duodenale (the hookworms).

STH affect more than 2 billion people worldwide. WHO estimates that A. lumbricoides infects over 1 billion people, T. trichiura 795 million, and hookworms (Ancylostoma duodenale and Necator americanus) 740 million.

The greatest numbers of soil-transmitted helminth infections occur in sub-Saharan Africa, the Americas, China and east Asia. Infection is caused by ingestion of eggs from contaminated soil (A. lumbricoides and T. trichiura) or by active penetration of the skin by larvae in the soil (hookworms).

Soil-transmitted helminths produce a wide range of symptoms including intestinal manifestations (diarrhoea, abdominal pain), general malaise and weakness, which may affect working and learning capacities and impair physical growth. Hookworms cause chronic intestinal blood loss that results in anaemia.

In 2001, the World Health Assembly – WHO’s decision-making body – resolved through Resolution 54.19 to attain by 2010 a minimum target of regular administration of chemotherapy to at least 75% and up to 100% of all school-age children at risk of morbidity from the disease.