Prevention and control of schistosomiasisand soil-transmitted helminthiasis

Comprehensive strategies for the prevention and control of worm infections, includingregular deworming of those at risk, have potential for significant impact on child health,growth and cognitive development.

1.Introduction

2.Methods

of control

3.Comprehensive

strategy

4.Conclusion

List ofabbreviations

CRC:

Conventionon the Rights

of the Child

IMCI:

IntegratedManagement of

Childhood Illness

FRESH:Focusing

Resourceson Effective

School Health

NVAP:

National VitaminA Programme

STH:

soil-transmittedhelminth

© World HealthOrganization, 2004All rights reserved.

World HealthOrganization

The burden of disease associated withhelminth infections (schistosomiasis andsoil-transmitted helminth (STH) infections)is enormous, with at least 2 billion peopleaffected worldwide. This is being increas-ingly recognized as a significant public healthproblem, particularly in developing countries,where poverty, poor nutrition, inadequatesanitation, lack of clean drinking-water andminimal health care prevail. The highestrates of infection are often in children betweenthe ages of 5 and 15 years.

Although these helminths can infect allmembers of a population, the most vulner-able groups – those who are at most risk,and who would benefit most from preventiveinterventions – are pre-school (age 2–5

years) and school-age children, adolescent

girls, and women of childbearing age.

Helminth infections have an adverse effecton cognitive development, and individualsin a period of intense physical and intellectualgrowth are extremely vulnerable. Despiteincreasing commitment to the health andlearning of schoolchildren, progress on thesefronts can be seriously threatened by helminthinfections. Studies have shown clearly thedetrimental effects of infection on educa-tional performance and school attendance,as well as the significant improvements inlanguage and memory development thatcan be realized following treatment. Helminthinfections are also associated with nutri-tional deficiencies, particularly of iron andvitamin A, with improvements in iron statusand increases in vitamin A absorption afterdeworming. Adolescent girls are particularlyat risk of anaemia aggravated by helminthinfection and iron stress.

WHO/CDS/CPE/PVC/2004.9

J O I N T S T A T E M E N T

1. INTRODUCTION

Credit: WHO/P. Virot

In order to promote and protect the rights ofeach child, including the “right to the enjoymentof the highest attainable standard of health andto facilities for the treatment of illness and re-habilitation of health” (CRC), illnesses thatplace an undue burden on child health and de-velopment must be effectively addressed.Furthermore, the creation of a safe, healthy, in-clusive and equitably resourced educationalenvironment, conducive to excellence in learn-

2. METHODS OF CONTROL

The overall objectives of preventing helminthinfections and schistosomiasis are to improvechildren’s health, nutrition and learning capa-bilities and to improve women’s lives and theircaring capacity, work efficiency and economicproductivity.

Recent evidence confirms that a significantreduction in the burden of disease due to theseinfections can be achieved through regularanthelminthic treatment directed to all high-riskgroups. Currently, a number of drugs areincluded in the WHO Model List of EssentialMedicines for the single-dose treatment of soil-transmitted helminths and schistosomiasis.The price of anthelminthics has now decreasedto a level that makes regular treatment bothaffordable and deliverable in a sustainablemanner through existing channels. It is esti-mated that most of the disease burden due tosoil-transmitted helminths and schistosomiasiscan be prevented in high-prevalence communitiesby treating pre-school and school-age children.

Both albendazole (400 mg) and mebendazole(500 mg) offer the further advantage that theycan be administered as a single tablet to allindividuals over 2 years of age. These drugsare effective, well tolerated and inexpensive andcan be safely given after the first trimester ofpregnancy. They are also safe for children between1 and 2 years of age (although the dose ofalbendazole has to be reduced to 200 mg).Praziquantel can now be easily administeredaccording to height with the aid of a “dose pole”and is also safe for pregnant women throughoutpregnancy. Studies in pregnant women haveshown that deworming is beneficial for thecourse of pregnancy, and that combiningtreatment with iron–folate supplementationhelps to improve iron status.

Anthelminthic treatment can be dispensedthrough health services (maternal and childhealth and antenatal clinics), school healthprogrammes, and community interventionsdirected at other vulnerable groups (such asadolescent girls). Repeated and regularchemotherapy of those at risk ensures thatlevels of infection are kept below thoseassociated with morbidity. Since reinfection iscommon, permanent control can be achievedonly through regular treatment accompanied bylong-term key preventive interventions in orderto break transmission routes:• provision and use of a safe and adequate

water supply;• improvement of environmental sanitation;• good sanitation and hygiene habits.

On the basis of the latest evidence and of arisk–benefit analysis (which took account ofdrug safety and the potential damage causedby these parasitic infections if left untreated), a2001 WHO informal consultation recommendedthat deworming campaigns should not excludeeither children aged 12 months onwards orpregnant women and adolescents.

ing, is an important condition for fulfilling the rightof all learners to an education of good quality.

In the outcome document of the United NationsGeneral Assembly’s Special Session on Childrenin May 2002, A World Fit for Children, worldleaders agreed to “reduce the incidence ofintestinal parasites” and to “reduce by one-thirdthe prevalence of anaemia, including iron-deficiency anaemia, by 2010”.

The WHO dose-pole is used by

a teacher todetermine the

correct dose ofpraziquantel.

somiasis and those for the control andelimination of other parasitic diseases suchas onchocerciasis and lymphatic filariasis.

Implementation of any helminth control pro-gramme will require strong linkages with keyprogrammes at the country level that arealready in place to reach women and children,working through existing regional, national andlocal activities. This could include:• IMCI, including community IMCI:• school-based programmes such as Sanitation

and Hygiene, and FRESH (Focusing Resourceson Effective School Health);

• vitamin A supplementation programmes;• maternal and child health;• reproductive health; Making Pregnancy Safer

being included;• Roll Back Malaria;• Expanded Programme on Immunization;• water and environmental sanitation.

The following important points should be keptin mind in planning a programme for control ofhelminth infections:

• Although regular treatment will help allchildren to avoid the worst effects of infection,long-term control will be achieved only ifregular treatment of at-risk groups isaccompanied by improvements in sanitation

and hygiene.

• Full impact on health will not be achievedunless helminth control is implemented aspart of a larger maternal and child health

strategy, aimed at reducing the burden ofanaemia in women, children and adolescentgirls.

• Where feasible, opportunities should besought for synergy between control measuresfor soil-transmitted helminths and schisto-

A comprehensive control strategy for helminthinfection should include:

• ensuring wide availability of anthelminthicsfor schistosomiasis and soil-transmittedhelminth infections in all health services inendemic areas;

• ensuring good case management of sympto-matic cases (e.g. IMCI);

• regular treatment of all children at risk, in-cluding adolescent girls, through school- andcommunity-based initiatives;

• treating pregnant women at risk, throughantenatal care and other women’s healthprogrammes;

• ensuring a safe water supply and adequatesanitation facilities in all schools;

• ensuring provision of potable water and sani-tation facilities at household/community level;

• promoting good hygiene and sanitationpractices among schoolchildren and care-givers (hand-washing, use of latrines, useof footwear) through community capacitydevelopment activities and in school curricula.

3. A COMPREHENSIVE STRATEGY

South Africa deworming schoolchildren for improved learning

In a rural settlement of Cape Town, South Africa, teachers and parents noticed that children were

falling asleep in school and were passing large numbers of worms, either in faeces or by vomiting.

A large survey in all 12 primary schools in the area found that more than 95% of all children

were infected with worms. These startling findings prompted the formation of a Task Team to

raise resources from private companies to deworm the children. Every 6 months, teachers and

school health nurses dewormed more than 11 000 children, reducing the proportion of children

infected to less than 20%. Capitalizing on the success of the deworming programme, the Task

Team continued their work with the school communities. As a result, all schools have established

action plans to improve the school environment and have integrated hygiene education into their

curricula; the local government has started to prioritize the area for sanitation resources.

Deworming improves health, nutrition andphysical development, makes pregnancy saferand improves birth outcomes. It is inexpensive,with a school-based deworming programmetypically costing between US$ 0.25 and 0.50per child per year.

The treatment is safe, even in pregnancy andwhen given to uninfected children. Finally,deworming can easily be added to existingactivities and programmes in health services,in school health programmes and in specialhealth campaigns. When regular deworming isaccompanied by appropriate sanitation andhygiene activities designed to prevent rein-fection, a long-term impact can be achieved.

Nepal integrates deworming activities with vitamin A supplementation

The Nepal National Vitamin A Programme (NVAP) provides an excellent opportunity to reachvirtually all young children twice a year. Phased integration of deworming of children aged2–5 years (single dose of albendazole, 400 mg) was therefore initiated in 14 districts in October1999. The integration has now reached 64 districts and the remaining districts will be coveredduring 2004.

The experience gained from integrating deworming with the vitamin A programme is positive.Since deworming is a very popular intervention, it lends even more importance to the twice-yearly distribution days and increases the appreciation of the community volunteers who conductthe distribution. Nutrition mini-surveys conducted after the introduction of deworming haveconsistently shown high coverage of both vitamin A and deworming, with more than 85% ofchildren being reached. Furthermore, after the initial training, no additional costs are associatedwith deworming beyond the cost of the tablets themselves.

The results of a recent study of the impact of deworming were remarkable. After only tworounds of treatment, the prevalence of helminth infection was reduced by 44% and there wasa dramatic reduction in infection intensity. As a result, there was a 77% reduction in anaemiaprevalence, from 47% at baseline to 11% after the two distribution rounds. The study clearlyshows that deworming will have far-reaching implications for child growth and cognitivedevelopment in Nepal.

Mr Edwin J. JuddDirector, Programme Division,UNICEF, New York

Dr A. Asamoa-BaahAssistant Director-GeneralCommunicable Diseases, WHO

4. CONCLUSION

R e f e r e n c e m a t e r i a l sHelminth control in school-age children: aguide for managers of control programmes.Geneva, World Health Organization, 2002.

Luong TV. Prevention of intestinal worminfections through improved sanitation andhygiene. Bangkok. UNICEF East Asia andPacific Regional Office, 2002.

Partners for Parasite Control (PPC)(www.who.int/wormcontrol).

Prevention and control of schistosomiasisand soil-transmitted helminthiasis. Reportof a WHO Expert Committee. Geneva,World Health Organization, 2002(WHO Technical Report Series, No. 912).

UNESCO, UNICEF, WHO, World Bank.Focusing Resources on Effective School Health:a FRESH start to enhancing the quality andequity of education (www.unicef.org/lifeskills/FreshDocument.pdf).