Abstract
Soil-transmitted helminthiasis (STH) is a group of infections caused by Ascaris lumbricoides, Trichuris trichiura and Necator americanus and Ancylostoma duodenale. The risk of acquiring STH is significantly influenced by climatic and socio-economic factors including temperature, rainfall, occupation and availability of safe water and sanitation facilities.
STH are transmitted through the parasites’ eggs excreted in faeces of infected humans that enter the human body by ingestion or skin penetration.
More than a billion people living in tropical and subtropical countries are currently infected with STH, with over 300 million of them suffering from morbidity.
The epidemiology of STH is characterized by overdispersed distribution in the population; heavy-intensity infections are the major source of morbidity and these infections usually occur in children and women; treatment administered at regular intervals to these groups at risk will periodically decrease the worm burden of infected individuals and control morbidity.
Soil-transmitted helminths can affect the nutritional status of their host by feeding on the content of the host’s intestine or on host tissues (e.g. blood), impairing digestion or absorption of nutrients, causing an inflammatory response that leads to the production of substances affecting appetite, intake, metabolism and storage of micronutrients and eliciting fever and immune response, thus increasing consumption of energy.
The burden of disease associated with STH is mainly attributable to their chronic and insidious impact on nutritional status, physical development and quality of life of those infected rather than to the overt morbidity or mortality they cause. The severity of the clinical manifestations mainly depends on the intensity of infection and on the underlying nutritional condition of the human host.
Eggs of intestinal helminths are generally easy to identify because of their large size and distinctive morphology and their identification in stool specimens remains the most commonly used means of diagnosis, especially in developing countries. The Kato-Katz technique direct smears in saline or concentration techniques (such as formol-ether) can be alternatively used.
WHO-recommended treatment options include albendazole, mebendazole, levamisole and pyrantel. All the mentioned medicines are to be administered orally. These drugs are effective, safe and extremely low cost. For these reasons, in area of high endemicity WHO recommends preventive chemotherapy; this measure consists on the large-scale distribution of anthelmintic drugs to population groups at risk. It has been demonstrated that treatment at regular intervals, when started early in life, protects children from the worst consequences of STH and prevents the development of complications associated with heavy-intensity infections.
One of the risks of this approach is the development of resistance to anthelmintic drugs in targeted parasites; as of today, however, scientific investigations have not demonstrated any presence of resistance among helminths that infect humans.
To further increase cost efficacy of the control activities WHO supports and endorses the development of multi-disease national plans of action (e.g. addressing also the control of schistosomiasis and lymphatic filariasis) implemented in integrated way and complemented by other public health interventions such as the provision of health education and the improvement of the sanitation infrastructure.
WHO envisages a world free of childhood morbidity due to STH. The goal is to reduce morbidity from STH among preschool-age children (aged 1–4 years) and school-age children (5–14 years) to a level below which it would not be considered a public health problem, i.e. when the level of prevalence of STH infections of moderate and high intensity among school-age children is <1%.
This target is achievable; in 2012 over 260 million of children have been treated with preventive chemotherapy for the control of STH and the large drug donations by pharmaceutical companies and the support provided by international donors are sustaining the efforts of endemic countries.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Anderson RM, May RM (1991) Infectious diseases of humans. Oxford University Press, Oxford
Beaumier CM, Gillespie PM, Hotez PJ, Bottazzi ME (2013) New vaccines for neglected parasitic diseases and dengue. Transl Res 162(3):144–155
Bundy DAP, Hall A, Medley GF, Savioli L (1992) Evaluating measures to control intestinal parasitic infections. World Health Stat Q 45:168–179
Casey GJ, Montresor A, Cavalli-Sforza LT, Thu H, Tinh TT, Tien NT, Phuc TQ, Biggs BA (2013) Elimination of iron deficiency anemia and soil transmitted helminth infection: evidence from a fifty-four month iron-folic acid and de-worming program. PLoS Negl Trop Dis 7(4):e2146
Crompton DW, Savioli L (1993) Intestinal parasitic infections and urbanization. Bull World Health Organ 71(1):1–7
Crompton DW, Nesheim MC (2002) Nutritional impact of intestinal helminthiasis during the human life cycle. Annu Rev Nutr 22:35–59
de Silva NR, Brooker S, Hotez PJ, MONTRESOR A, Engels D, Savioli L (2003) Soil-transmitted helminth infections: updating the global picture. Trends Parasitol 19(12):547–551
Gabrielli AF, Ramsan M, Naumann C, Tsogzolmaa D, Bojang B, Khoshal MH, Connolly M, Stothard JR, Montresor A, Savioli L (2005) Soil-transmitted helminths and haemoglobin status among Afghan children in World Food Programme assisted schools. J Helminthol 79(4):381–384
Gabrielli AF, Montresor A, Chitsulo L, Engels D, Savioli L (2011) Preventive chemotherapy in human helminthiasis: theoretical and operational aspects. Trans R Soc Trop Med Hyg 105(12):683–693
Gunn A, Pitt SJ (2012) Parasitology. An integrated approach. Wiley-Blackwell, Chichester
Guyatt HL, Bundy DA, Evans D (1993) A population dynamic approach to the cost-effectiveness analysis of mass anthelminthic treatment: effects of treatment frequency on Ascaris infection. Trans R Soc Trop Med Hyg 87:570–575
Hall A, Hewitt G, Tuffrey V, de Silva N (2008) A review and meta-analysis of the impact of intestinal worms on child growth and nutrition. Matern Child Nutr 4(Suppl 1):118–236
Harvey PA (2011) Zero subsidy strategies for accelerating access to rural water and sanitation services. Water Sci Technol 63(5):1037–1043
Montresor A (2011) Cure rate is not a valid indicator for assessing drug efficacy and impact of preventive chemotherapy interventions against schistosomiasis and soil-transmitted helminthiasis. Trans R Soc Trop Med Hyg 105:360–363
Montresor A, Gabrielli AF, Diarra A, Engels D (2010) Estimation of the cost of large-scale school deworming programmes with benzimidazoles. Trans R Soc Trop Med Hyg 104(2):129–132
Montresor A, Gabrielli AF, Yajima A, Lethanh N, Biggs BA, Casey GJ, Tinh TT, Engels D, Savioli L (2013) Markov model to forecast the change in prevalence of soil-transmitted helminths during a control programme: a case study in Vietnam. Trans R Soc Trop Med Hyg 107:313–318
Murray CJL, Vos T, Lozano R et al (2012) Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 380:2197–2223
Nokes C, Grantham-McGregor SM, Sawyer AW, Cooper ES, Bundy DA (1992) Parasitic helminth infection and cognitive function in school children. Proc Biol Sci 247(1319):77–81
Stoltzfus RJ, Albonico M, Chwaya HM, Savioli L, Tielsch J, Schulze K, Yip R (1996) Hemoquant determination of hookworm-related blood loss and its role in iron deficiency in African children. Am J Trop Med Hyg 55:399–404
Tun A, Myat SM, Gabrielli AF, Montresor A (2013) Control of soil transmitted helminthiasis in Myanmar. Result of 7 years of deworming. Trop Med Int Health 18(8):1017–1020
World Health Organization (1994) Bench aids for the diagnosis of intestinal parasites. 2012. Reprint. World Health Organization, Geneva
World Health Organization (1996) Report of the WHO informal consultation on the use of chemotherapy for the control of morbidity due to soil-transmitted nematodes in humans, Geneva, 29 April–1 May 1996. Division of Control of Tropical Diseases, Geneva. WHO/CTD/SIP.96.2
World Health Organization (1998) Integrating disease control: the challenge. Division of Control of Tropical Diseases, Geneva. WHO/CTD/98.7
World Health Organization (2001) Resolution WHA54.19. Schistosomiasis and soil-transmitted helminth infections. http://www.who.int/neglected_diseases/mediacentre/WHA_54.19_Eng.pdf
World Health Organization (2002) Prevention and control of schistosomiasis and soil-transmitted helminthiasis. Report of a WHO Expert Committee. WHO technical report series 912. World Health Organization, Geneva
World Health Organization (2006) Preventive chemotherapy in human helminthiasis. Coordinated use of anthelminthic drugs in control interventions: a manual for health professionals and programme managers. World Health Organization, Geneva
World Health Organization (2007) A turning point. Report of the global partners’ meeting on neglected tropical diseases. World Health Organization, . Geneva
World Health Organization (2008) The global burden of disease—2004 update. World Health Organization, Geneva
World Health Organization (2009) WHO Model Formulary 2008. Based on the 15th model list of essential medicines 2007. World Health Organization, Geneva
World Health Organization (2012a) Soil-transmitted helminthiasis. Eliminating soil-transmitted helminthiasis as a public health problem in children. Progress report 2001–2010 and strategic plan 2011–2020. World Health Organization, Geneva
World Health Organization (2012b) Soil-transmitted helminthiasis: number of children treated in 2010. Wkly Epidemiol Rec 23:225–232
World Health Organization (2013a) Soil-transmitted helminthiases: number of children treated in 2011. Wkly Epidemiol Rec 24:145–152
World Health Organization (2013b) Assessing the efficacy of anthelminthic drugs against schistosomiasis and soil-transmitted helminthiases. World Health Organization, Geneva
World Health Organization (2013c) Resolution WHA66.12. Neglected tropical diseases. http://www.who.int/entity/neglected_diseases/mediacentre/WHA_66.12_Eng.pdf
Yokogawa M (1985) JOICFP’S experience in the control of ascariasis within an integrated programme. In: Crompton DWT, Nesheim MC, Pawlowski ZS (eds) Ascariasis and its public health significance. Taylor and Francis, London and Philadelphia, pp 265–277
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2014 Springer-Verlag Wien
About this chapter
Cite this chapter
Gabrielli, A.F., Montresor, A., Savioli, L. (2014). Soil-Transmitted Helminthiasis. In: Bruschi, F. (eds) Helminth Infections and their Impact on Global Public Health. Springer, Vienna. https://doi.org/10.1007/978-3-7091-1782-8_9
Download citation
DOI: https://doi.org/10.1007/978-3-7091-1782-8_9
Published:
Publisher Name: Springer, Vienna
Print ISBN: 978-3-7091-1781-1
Online ISBN: 978-3-7091-1782-8
eBook Packages: Biomedical and Life SciencesBiomedical and Life Sciences (R0)