Soil-transmitted helminths

Soil-transmitted helminthiases severely affect public health and particularly, school-aged children. A number of epidemiologic studies estimate that, globally, there are 870 million children at risk of getting infected with some of these parasites. The consequences on the health of those suffering these infections are alarming: hosts usually present poor cognitive development, malnutrition, anemia and general growth disorders. In adults, the infection causes pain, diarrhea, weakness and hypovitaminosis A, all of which severely affects their quality of life and work performance.
These worm infections are caused by a group of parasites transmitted through the soil because their larvae or eggs, which are eliminated in the feces of infected people, need this passage in order to become infective. There are five different helminth species that infect human beings exclusively, including, Ascaris lumbricoides and Trichuris trichiura (which infect individuals when they ingest their eggs), the hookworms Necator americanus and Ancylostoma duodenale and Strongyloides stercolaris (which infect individuals when the larvae penetrates the skin).

The standard diagnosis of current infection is made through the detection of parasite eggs or larvae in fecal samples using a microscope, as they are not visible to the naked eye.

These parasites live in the infected person’s intestine and their eggs and/or larvae are excreted in the feces, which is why soil-transmitted helminthiases are more prevalent in regions of the world where populations lack access to safe water and basic sanitation, which consequently impacts good personal hygiene.

Untreated helminthiases may cause unspecific symptoms, including headache, stomach cramps, and diarrhea, among others. Mild infections are usually asymptomatic. On the other hand, people with a severe infections (large number of parasites in their intestine) usually suffer greater consequences, including intestinal obstruction or rectal prolapse (mainly in children), anemia (mainly in children and pregnant women) or hyperinfections where the parasite may spread all over the body (especially in immunocompromised individuals). Because these parasites are more frequently present in children living in places with sub-standard quality of life, the anemia caused by the infection ends up affecting their growth and cognitive development, especially if they lack a well-balanced nutrition.


Since there are effective drugs against these parasites, which affect mainly school-aged children all over the world, the World Health Organization (WHO) developed basic guidelines to control the morbidity caused by soil-transmitted helminthiases. These guidelines are based on single-dose treatments with Albendazole or Mebendazole, administered at school once or twice a year, depending on the percent of infected children, as follows:
• if the percent of infected children is below 20%, they are treated individually;
• if the percentage ranges between 20% and 50%, all children in the school receive treatment (mass administration) once a year;
• if the percentage is above 50%, all children in school receive treatment (mass administration) twice a year.

While these guidelines are useful to prevent the serious consequences of heavy soil-transmitted helminth infections in school-aged children, mass treatment per se is not enough to stop transmission to other people for three main reasons:  1) a single dose of Albendazole or Mebendazole does not cure children completely (and hence they continue to expel eggs or larvae in their feces); 2) adults are not treated and so they can, too, continue to expel eggs or larvae in their feces (especially, in hookworm infections); and 3) neither of the drugs used by the WHO is effective against Strongyloides stercoralis.

These reasons are why the community continues to have these parasites and requires the maintenance of mass treatment programs in schools for long periods of time.
In order to successfully interrupt the parasites´ transmission cycle, the life conditions of affected populations need to be improved, by providing education, safe water and sanitation.

For all of this, Mundo Sano works with communities, for the purpose of:
• determining the presence of these parasites;
• identifying which of soil-transmitted helminth species are the most frequent;
• studying the characteristics and/or conditions that make some communities more or less prone to having helminths;
• measuring the effectiveness of the various drugs or their combinations to successfully remove all helminth species;
• determining the impact of parasitological treatment combined with access to water and sanitation on transmission of these parasites;
• performing activities to promote health education and hygiene in order to help prevent infection.Africa y Argentina

“These portraits are pictures taken in 2014 by the artist Ezequiel Romairone for the series titled “Two Continents, One World.” They were taken in areas of Argentina and Ethiopia where Fundación Mundo Sano works to reduce the impact of neglected tropical diseases. The likeness of images was found by chance.”

Work in Africa

In 2013, Mundo Sano, together with the National Tropical Medicine Centre of the Carlos III Health Institute of Madrid (Spain) and national Ethiopian institutions, including the Bahir Dar University, expanded their field of action on soil-transmitted helminthiases to African territories, more precisely in the Bahir Dar area (Amhara Region) Ethiopia, to conduct work for the diagnosis and treatment of Strongyloides stercolaris and other NTDs.

A new collaborative project was started in Africa in 2015, with a focus on helminthiases in Manhiça (Mozambique), together with the Manhiça Health Research Center (CISM) and the Global Health Institute (ISGLOBAL) of Barcelona (Spain). In line with this collaboration, in 2016, Fundación Mundo Sano organized the training in coproparasitological diagnosis of the CISM parasitology laboratory staff. Training was performed on-site by a technician from the Parasitology Laboratory of the National Administration of Laboratories and Institutes of Health (ANLIS) “Carlos G. Malbrán” of the Ministry of Health of Argentina.

All the work conducted in Argentina and Africa has been published in different scientific media that can be accessed in the following website:

Work in Argentina

Since 2010, Mundo Sano conducts studies on soil-transmitted helminthiasis diagnosis and treatment in cooperation with the Tropical Disease Research Institute and the Experimental Pathology Institute of the Salta National University, based in Oran and Tartagal, two localities of the Argentine North-Western area.

The Salta program includes, among other activities, the validation of a serologic test for Strongyloides stercoralis detection. The study also focuses on two drugs already tested for various parasitic diseases, Ivermectin and Albendazole, coformulated to have both active principles present in one pill that can be administered in a single dose for mass treatment. The development of this idea is under joint charge of Mundo Sano and Laboratorios ELEA, for the purpose of making available an effective medicine against all soil-transmitted helminths, including Strongyloides.

Since 2014, Mundo Sano has been conducting soil-transmitted helminth projects in other Argentine localities, such as Añatuya (Santiago del Estero) and Pampa del Indio (Chaco) where, in addition to diagnosis and treatment, other components were included, such as helminthiasis prevention and control through the improvement of water, sanitation and hygiene. This work was done in cooperation with the Parasitology Laboratory of ANLIS.

In light of the significance of good hygiene in preventing soil-transmitted helminth infections, among other diseases caused by intestinal parasites, bacteria and viruses, on October 14, 2016, we joined in the celebration of the Global Hand Washing Day, an international initiative organized by The Global Public-Private Partnership for Handwashing, to work on the importance of correct hand washing in preventing diseases and saving lives. On that day, more than 200 children from Puerto Iguazú (Misiones, Argentina) participated in a play-and-learn activity organized by Mundo Sano.

Video of the activity:

Further information:

Alliance against soil-transmitted helminths:

In the framework of Uniting to combat NTDs, an international alliance created in London in 2012 to fight neglected tropical diseases, we, as the only Latin American organization member of the alliance, decided to join a new work group called STH Coalition, the objective of which is to increase efforts to combat soil-transmitted helminthiases.

In April 2014, Mundo Sano and other organizations committed to tearing down barriers to the access to helminthiasis diagnosis, treatment and research and decided to focus our work on improving access to anti-parasite medications and preventing reinfection.

In addition to Mundo Sano, the STH Coalition is currently comprised of the Bill & Melinda Gates Foundation, USAID, the World Health Organization (WHO), the Children’s Investment Fund Foundation (CIFF), Dubai Cares, Vitamin Angels, WaterAid, Global Partnership for Education (GPE), World Bank Group and World Food Programme (WFP), among 50 other organizations from different fields such as public health, education, water, sanitation, hygiene, mother and child health, nutrition and global development.

More at:


 “Puerto Iguazú, Misiones, Argentina. This photo is part of the series “Two Continents, One World” created by the artist Ezequiel Romairone in 2014”

Since late April 2017, we are cooperating with The Neglected Tropical Disease NGO Network (NNN) working with other nongovernmental organizations of international renown in attaining common goals against neglected diseases including, among other, soil-transmitted helminthiases and leprosy. This forum was created in 2009 to give response to the needs of million people living in poverty in marginal and remote areas of the world affected by diseases that can be prevented and treated.

Their members work in these issues in different countries and participate in the NNN network aiming to assist in their control, management and elimination, within the framework of the WHO’s global strategy.

Once again, we, at Mundo Sano are contributing our experience and commitment to a new cooperation proposal to change the reality of the communities affected by neglected tropical diseases.

More at: