Who misses out with school-based health programmes? a study of schistosomiasis control in Egypt

Associations of water contact frequency, duration, and activities with schistosome infection risk: A systematic review and meta-analysis

BACKGROUND

Schistosomiasis is a water-borne parasitic disease which affects over 230 million people globally. The relationship between contact with open freshwater bodies and the likelihood of schistosome infection remains poorly quantified despite its importance for understanding transmission and parametrising transmission models.

METHODS

We conducted a systematic review to estimate the average effect of water contact duration, frequency, and activities on schistosome infection likelihood. We searched Embase, MEDLINE (including PubMed), Global Health, Global Index Medicus, Web of Science, and the Cochrane Central Register of Controlled Trials from inception until May 13, 2022. Observational and interventional studies reporting odds ratios (OR), hazard ratios (HR), or sufficient information to reconstruct effect sizes on individual-level associations between water contact and infection with any Schistosoma species were eligible for inclusion. Random-effects meta-analysis with inverse variance weighting was used to calculate pooled ORs and 95% confidence intervals (CIs).

RESULTS

We screened 1,411 studies and included 101 studies which represented 192,691 participants across Africa, Asia, and South America. Included studies mostly reported on water contact activities (69%; 70/101) and having any water contact (33%; 33/101). Ninety-six percent of studies (97/101) used surveys to measure exposure. A meta-analysis of 33 studies showed that individuals with water contact were 3.14 times more likely to be infected (OR 3.14; 95% CI: 2.08-4.75) when compared to individuals with no water contact. Subgroup analyses showed that the positive association of water contact with infection was significantly weaker in children compared to studies which included adults and children (OR 1.67; 95% CI: 1.04-2.69 vs. OR 4.24; 95% CI: 2.59-6.97). An association of water contact with infection was only found in communities with ≥10% schistosome prevalence. Overall heterogeneity was substantial (I2 = 93%) and remained high across all subgroups, except in direct observation studies (I2 range = 44%-98%). We did not find that occupational water contact such as fishing and agriculture (OR 2.57; 95% CI: 1.89-3.51) conferred a significantly higher risk of schistosome infection compared to recreational water contact (OR 2.13; 95% CI: 1.75-2.60) or domestic water contact (OR 1.91; 95% CI: 1.47-2.48). Higher duration or frequency of water contact did not significantly modify infection likelihood. Study quality across analyses was largely moderate or poor.

CONCLUSIONS

Any current water contact was robustly associated with schistosome infection status, and this relationship held across adults and children, and schistosomiasis-endemic areas with prevalence greater than 10%. Substantial gaps remain in published studies for understanding interactions of water contact with age and gender, and the influence of these interactions for infection likelihood. As such, more empirical studies are needed to accurately parametrise exposure in transmission models. Our results imply the need for population-wide treatment and prevention strategies in endemic settings as exposure within these communities was not confined to currently prioritised high-risk groups such as fishing populations.

Precision mapping of schistosomiasis and soil-transmitted helminthiasis among school age children at the coastal region, Kenya

BACKGROUND

Accurate mapping of schistosomiasis (SCH) and soil transmitted helminths (STH) is a prerequisite for effective implementation of the control and elimination interventions. A precision mapping protocol was developed and implemented in the coastal region of Kenya by applying the current World Health Organization (WHO) mapping guide at a much lower administrative level (ward).

METHODS

A two-stage cluster survey design was undertaken, with 5 villages in each ward selected. From within each village 50 households were randomly selected, and a single child between the ages of 8 and 14 sampled following appropriate assent. The prevalence and intensity of infection of Schistosoma mansoni and STH were determined using the Kato-Katz method (single stool, duplicate slides) and urine filtration for S. haematobium.

RESULTS

Of the 27,850 school age children sampled, 6.9% were infected with at least one Schistosoma species, with S. haematobium being the most common 6.1% (95% CI: 3.1-11.9), and Tana River County having highest prevalence 19.6% (95% CI: 11.6-31.3). Prevalence of any STH infection was 5.8% (95% CI: 3.7-8.9), with Lamu County having the highest prevalence at 11.9% (95% CI: 10.0-14.1). The most prevalent STH species in the region was Trichuris trichiura at 3.1% (95% CI: 2.0-4.8). According to the WHO threshold for MDA implementation, 31 wards (in 15 sub-Counties) had a prevalence of ≥10% for SCH and thus qualify for annual MDA of all age groups from 2 years old. On the other hand, using the stricter Kenya BTS MDA threshold of ≥2%, 72 wards (in 17 sub-Counties) qualified for MDA and were targeted for treatment in 2021.

CONCLUSIONS

The precision mapping at the ward level demonstrated the variations of schistosomiasis prevalence and endemicity by ward even within the same sub-counties. The data collected will be utilized by the Kenyan Ministry of Health to improve targeting.

Cognitive deficits and educational loss in children with schistosome infection-A systematic review and meta-analysis

Background

By means of meta-analysis of information from all relevant epidemiologic studies, we examined the hypothesis that Schistosoma infection in school-aged children (SAC) is associated with educational loss and cognitive deficits.

Methodology/Principal findings

This review was prospectively registered in the PROSPERO database (CRD42016040052). Medline, Biosis, and Web of Science were searched for studies published before August 2016 that evaluated associations between Schistosoma infection and cognitive or educational outcomes. Cognitive function was defined in four domains—learning, memory, reaction time, and innate intelligence. Educational outcome measures were defined as attendance and scholastic achievement. Risk of bias (ROB) was evaluated using the Newcastle-Ottawa quality assessment scale. Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated to compare cognitive and educational measures for Schistosoma infected /not dewormed vs. uninfected/dewormed children. Sensitivity analyses by study design, ROB, and sequential exclusion of individual studies were implemented. Thirty studies from 14 countries, including 38,992 SAC between 5–19 years old, were identified. Compared to uninfected children and children dewormed with praziquantel, the presence of Schistosoma infection and/or non-dewormed status was associated with deficits in school attendance (SMD = -0.36, 95%CI: -0.60, -0.12), scholastic achievement (SMD = -0.58, 95%CI: -0.96, -0.20), learning (SMD = -0.39, 95%CI: -0.70, -0.09) and memory (SMD = -0.28, 95%CI: -0.52, -0.04) tests. By contrast, Schistosoma-infected/non-dewormed and uninfected/dewormed children were similar with respect to performance in tests of reaction time (SMD = -0.06, 95%CI: -0.42, 0.30) and intelligence (SMD = -0.25, 95%CI: -0.57, 0.06). Schistosoma infection-associated deficits in educational measures were robust among observational studies, but not among interventional studies. The significance of infection-associated deficits in scholastic achievement was sensitive to ROB. Schistosoma infection-related deficits in learning and memory tests were invariant by ROB and study design.

Conclusion/Significance

Schistosoma infection/non-treatment was significantly associated with educational, learning, and memory deficits in SAC. Early treatment of children in Schistosoma-endemic regions could potentially mitigate these deficits.

Trial registration

ClinicalTrials.gov CRD42016040052

Empirical evidence for cognitive or educational benefits of anti-Schistosoma treatment is currently uncertain, despite the recommended practice of wide-scale deworming with praziquantel. We addressed this knowledge gap by synthesizing information from 30 relevant epidemiologic studies reporting on 38,992 children between 5–19 years old from 14 countries. In those studies, Schistosoma infection or non-dewormed status was associated with educational loss and cognitive deficits. Specifically, there were small to moderate deficits in both school attendance and scholastic achievement. Similarly, Schistosoma infection or non-dewormed status was associated with deficits in learning and memory domains of psychometrically tested cognitive function. However, there was no evidence of Schistosoma infection- or non-deworming-associated deficits on tests of innate intelligence or reaction-time. Overall, compared to Schistosoma-uninfected or to dewormed children, the presence of Schistosoma infection or non-dewormed status was associated with educational, learning, and memory deficits in school-aged children. The combined evidence suggests that early treatment of children in Schistosoma-endemic regions could mitigate these deficits.

School-based mass distributions of mebendazole to control soil-transmitted helminthiasis in the Munshiganj and Lakshmipur districts of Bangladesh: an evaluation of the treatment monitoring process and knowledge, attitudes, and practices of the population

Bangladesh's national deworming program targets school-age children (SAC) through bi-annual school-based distributions of mebendazole. Qualitative and quantitative methods were applied to identify challenges related to treatment monitoring within the Munshiganj and Lakshmipur Districts of Bangladesh. Key stakeholder interviews identified several obstacles for successful treatment monitoring within these districts; ambiguity in defining the target population, variances in the methods used for compiling and reporting treatment data, and a general lack of financial and human resources. A treatment coverage cluster survey revealed that bi-annual primary school-based distributions proved to be an effective strategy in reaching school-attending SAC, with rates between 63.0% and 73.3%. However, the WHO target of regular treatment of at least 75% of SAC has yet to be reached. Particularly low coverage was seen amongst non-school attending children (11.4-14.3%), most likely due to the lack of national policy to effectively target this vulnerable group. Survey findings on water and sanitation coverage were impressive with the majority of households and schools having access to latrines (98.6-99.3%) and safe drinking water (98.2-100%). The challenge now for the Bangladesh control program is to achieve the WHO target of regular treatment of at least 75% of SAC at risk, irrespective of school-enrollment status.

Projecting the long-term impact of school- or community-based mass-treatment interventions for control of Schistosoma infection

Background

Schistosomiasis remains a significant health burden in many areas of the world. Morbidity control, focused on limiting infection intensity through periodic delivery of anti-schistosomal medicines, is the thrust of current World Health Organization guidelines (2006) for reduction of Schistosoma-related disease. A new appreciation of the lifetime impact of repeated Schistosoma infection has directed attention toward strategies for greater suppression of parasite infection per se, with the goal of transmission interruption. Variations in drug schedules involving increased population coverage and/or treatment frequency are now undergoing field trials. However, their relative effectiveness in long-term infection suppression is presently unknown.

Methodology/Principal Findings

Our study used available field data to calibrate advanced network models of village-level Schistosoma transmission to project outcomes of six different community- or school age-based programs, as compared to the impact of current 2006 W.H.O. recommended control strategies. We then scored the number of years each of 10 typical villages would remain below 10% infection prevalence (a practicable level associated with minimal prevalence of disease). All strategies that included four annual treatments effectively reduced community prevalence to less than 10%, while programs having yearly gaps (‘holidays’) failed to reach this objective in half of the communities. Effective post-program suppression of infection prevalence persisted in half of the 10 villages for 7–10 years, whereas in five high-risk villages, program effects on prevalence lasted zero to four years only.

Conclusions/Significance

At typical levels of treatment adherence (60 to 70%), current WHO recommendations will likely not achieve effective suppression of Schistosoma prevalence unless implemented for ≥6 years. Following more aggressive 4 year annual intervention, some communities may be able to continue without further intervention for 8–10 years, while in higher-risk communities, annual treatment may prove necessary until eco-social factors fostering transmission are removed. Effective ongoing surveillance and locally targeted annual intervention must then become their mainstays of control.

Debate persists about how best to prevent disease caused by Schistosoma parasites. Current guidelines focus on suppressing morbidity by limiting average intensity of infection during childhood. However, this may not be sufficient to cure infection or prevent reinfection, leaving risk for sub-clinical morbidities such as growth stunting and anemia. More intensive programs involving broader coverage and/or more frequent treatments could potentially cure most infections and even prevent their return. Because such programs' effectiveness is not currently known, we used computer simulation (grounded by past treatment program results) to project short- and long-term impact in communities where Schistosoma are common. We estimated that 4 annual treatments (delivered community-wide or only to school-age children and high-risk adults) could effectively reduce local prevalence below 10%. Programs with gap years were less effective, particularly in high-risk communities. If a program was successful, infection stayed <10% for 7–10 years in low risk communities. However, rapid resurgence (within 1–5 years) was projected for high risk villages. We conclude that, given the networked transmission of Schistosoma, annual treatment programs of sufficient duration can have secondary benefits, i.e., long-term suppression in some areas. However, high risk areas will need continuing surveillance and frequent retreatment to truly minimize their risk for disease.

Urine heme dipsticks are useful in monitoring the impact of praziquantel treatment on Schistosoma haematobium in sentinel communities of Delta State, Nigeria

Nigeria is highly endemic for infection with Schistosoma haematobium, which most commonly manifests itself with blood in urine. To monitor the impact of annual mass drug administration (MDA) with Praziquantel for S. haematobium in Delta State, Nigeria, cross-sectional hematuria surveys of school children were conducted in 8 sentinel villages (SVs) at baseline (n=240) and after two annual doses (n=402). We assessed the comparability of three assessments of hematuria (child's reported history, nurse visual diagnosis (NVD) and dipstick) to determine the need for mass treatment. Dipstick was considered to be the gold standard. Prior to treatment, history and NVD each identified only the 3 most highly prevalent SVs, and overall this represented just 37.5% of the 8 SVs in need of treatment. Following treatment, after dipstick prevalence decreased by 88.5% (p<0.001), and history and NVD identified only one of two villages still needing treatment. The study suggests that dipsticks should be the recommended method for launching and monitoring mass treatment for S. haematobium.

Schistosomiasis and soil-transmitted helminth control in Niger: cost effectiveness of school based and community distributed mass drug administration [corrected]

BACKGROUND

In 2004 Niger established a large scale schistosomiasis and soil-transmitted helminths control programme targeting children aged 5-14 years and adults. In two years 4.3 million treatments were delivered in 40 districts using school based and community distribution.

METHOD AND FINDINGS

Four districts were surveyed in 2006 to estimate the economic cost per district, per treatment and per schistosomiasis infection averted. The study compares the costs of treatment at start up and in a subsequent year, identifies the allocation of costs by activity, input and organisation, and assesses the cost of treatment. The cost of delivery provided by teachers is compared to cost of delivery by community distributers (CDD). The total economic cost of the programme including programmatic, national and local government costs and international support in four study districts, over two years, was US$ 456,718; an economic cost/treatment of $0.58. The full economic delivery cost of school based treatment in 2005/06 was $0.76, and for community distribution was $0.46. Including only the programme costs the figures are $0.47 and $0.41 respectively. Differences at sub-district are more marked. This is partly explained by the fact that a CDD treats 5.8 people for every one treated in school. The range in cost effectiveness for both direct and direct and indirect treatments is quantified and the need to develop and refine such estimates is emphasised.

CONCLUSIONS

The relative cost effectiveness of school and community delivery differs by country according to the composition of the population treated, the numbers targeted and treated at school and in the community, the cost and frequency of training teachers and CDDs. Options analysis of technical and implementation alternatives including a financial analysis should form part of the programme design process.

Towards nationwide control of schistosomiasis in Yemen: a pilot project to expand treatment to the whole community

Both the urinary and intestinal forms of schistosomiasis are thought to be widespread in the Republic of Yemen, with estimates of 3 million people infected and 600 000 suffering clinical morbidity. Sub-national control has been ongoing since 2006 via the distribution of praziquantel (PZQ) against schistosomiasis and albendazole (ALB) against soil-transmitted helminths using school-based treatment. In preparation for a 6-year nationwide control programme with the aim of expanding treatment to the wider community, a new programmatic approach of complementing school-based distribution with community-based treatment was trialled in 10 highly endemic districts in three governorates in December 2009. The new approach achieved coverage of 90.1% of non-enrolled children: a 40% increase compared with the same districts in 2008, and coverage of 97.9% of enrolled children: a 2% increase compared to 2008. Coverage of females (children and adults) was 81.8%, and of adults in general was 73.9%. The total cost per person treated was US$0.66 (US$0.79 in 2008), which includes training, health education, social mobilization, distribution and drugs. These results provide hope that a combined school and community-based approach can be successfully implemented on a wider scale during the main control programme in 2010-2015, with approximately 10 million people targeted in the first year alone.

Treatment coverage survey after a school-based mass distribution of mebendazole: Kampot Province, Cambodia

In efforts to reduce the global burden of soil transmitted helminth (STH) infections in school age children (SAC, 6-14 years old), Children Without Worms donates mebendazole to 8 countries with high prevalence of STH infections. Cambodia's national deworming program currently targets SAC through bi-annual school-based distributions of a single dose of mebendazole. A 30-cluster household survey was conducted in the rural province Kampot, to validate mebendazole treatment coverage in SAC and to assess the level of improved water supply and sanitation. Bi-annual primary school-based distributions proved to be an effective strategy in reaching school attending SAC, with treatment coverage rates between 84.1% and 88.8%. However, significantly lower rates (23.3-48.8%) were seen among SAC not enrolled in primary schools. Often members of the most marginalized families of the community, they are particularly at risk of STH infection. Methods to reach these children need to be explored to avoid treatment inequities.

Observed reductions in Schistosoma mansoni transmission from large-scale administration of praziquantel in Uganda: a mathematical modelling study

Background

To date schistosomiasis control programmes based on chemotherapy have largely aimed at controlling morbidity in treated individuals rather than at suppressing transmission. In this study, a mathematical modelling approach was used to estimate reductions in the rate of Schistosoma mansoni reinfection following annual mass drug administration (MDA) with praziquantel in Uganda over four years (2003–2006). In doing this we aim to elucidate the benefits of MDA in reducing community transmission.

Methods

Age-structured models were fitted to a longitudinal cohort followed up across successive rounds of annual treatment for four years (Baseline: 2003, Treatment: 2004–2006; n = 1,764). Instead of modelling contamination, infection and immunity processes separately, these functions were combined in order to estimate a composite force of infection (FOI), i.e., the rate of parasite acquisition by hosts.

Results

MDA achieved substantial and statistically significant reductions in the FOI following one round of treatment in areas of low baseline infection intensity, and following two rounds in areas with high and medium intensities. In all areas, the FOI remained suppressed following a third round of treatment.

Conclusions/Significance

This study represents one of the first attempts to monitor reductions in the FOI within a large-scale MDA schistosomiasis morbidity control programme in sub-Saharan Africa. The results indicate that the Schistosomiasis Control Initiative, as a model for other MDA programmes, is likely exerting a significant ancillary impact on reducing transmission within the community, and may provide health benefits to those who do not receive treatment. The results obtained will have implications for evaluating the cost-effectiveness of schistosomiasis control programmes and the design of monitoring and evaluation approaches in general.

Schistosomiasis is a parasitic disease of enormous public health importance, infecting over 200 million people worldwide, of which the large majority live in sub-Saharan Africa. Control programmes based on the mass treatment of individuals in infected areas with the drug praziquantel have been shown to be successful in reducing the parasite burden and likelihood of developing morbidity in those individuals who receive treatment. Using data from an ongoing intestinal schistosomiasis control programme in Uganda and through the application of a mathematical model, we show that an additional benefit of mass treatment is a decrease in parasite acquisition, via a reduction in the number of transmission stages in the environment. This leads to a lower rate of infection and reinfection of individuals in those areas. We show that this result is valid in areas of differing average infection intensity. The importance of this finding is that this will benefit untreated as well as treated individuals, and will allow a fuller estimation of the benefits of schistosomiasis control programmes.

Parasites and poverty: the case of schistosomiasis

Simultaneous and sequential transmission of multiple parasites, and their resultant overlapping chronic infections, are facts of life in many underdeveloped rural areas. These represent significant but often poorly measured health and economic burdens for affected populations. For example, the chronic inflammatory process associated with long-term schistosomiasis contributes to anaemia and undernutrition, which, in turn, can lead to growth stunting, poor school performance, poor work productivity, and continued poverty. To date, most national and international programs aimed at parasite control have not considered the varied economic and ecological factors underlying multi-parasite transmission, but some are beginning to provide a coordinated approach to control. In addition, interest is emerging in new studies for the re-evaluation and recalibration of the health burden of helminthic parasite infection. Their results should highlight the strong potential of integrated parasite control in efforts for poverty reduction.

Social science perspectives on schistosomiasis control in Africa: past trends and future directions

New ways of integrating and scaling up control of neglected tropical diseases (including schistosomiasis) are presently underway. In this context consideration of social science perspectives is essential. In this article, we review social science publications of relevance to sustained control of schistosomiasis in Africa including diagnosis and screening, treatment, supply of clean water and improved sanitation, as well as health communication. Studies of community involvement and links between schistosomiasis control programmes and broader health care systems are also explored. Directions for future social science of relevance to sustainable schistosomiasis control are outlined, including ways of ensuring equitable access to health services as well as involvement of endemic communities and local health care systems based on equal partnership.

Can coverage of schistosomiasis and soil transmitted helminthiasis control programmes targeting school-aged children be improved? New approaches

Control programmes generally use a school-based strategy of mass drug administration to reduce morbidity of schistosomiasis and soil-transmitted helminthiasis (STH) in school-aged populations. The success of school-based programmes depends on treatment coverage. The community-directed treatment (ComDT) approach has been implemented in the control of onchocerciasis and lymphatic filariasis in Africa and improves treatment coverage. This study compared the treatment coverage between the ComDT approach and the school-based treatment approach, where non-enrolled school-aged children were invited for treatment, in the control of schistosomiasis and STH among enrolled and non-enrolled school-aged children. Coverage during the first treatment round among enrolled children was similar for the two approaches (ComDT: 80·3% versus school: 82·1%, P=0·072). However, for the non-enrolled children the ComDT approach achieved a significantly higher coverage than the school-based approach (80·0 versus 59·2%, P<0·001). Similar treatment coverage levels were attained at the second treatment round. Again, equal levels of treatment coverage were found between the two approaches for the enrolled school-aged children, while the ComDT approach achieved a significantly higher coverage in the non-enrolled children. The results of this study showed that the ComDT approach can obtain significantly higher treatment coverage among the non-enrolled school-aged children compared to the school-based treatment approach for the control of schistosomiasis and STH.

The effect of the community-directed treatment approach versus the school-based treatment approach on the prevalence and intensity of schistosomiasis and soil-transmitted helminthiasis among schoolchildren in Tanzania

This study compared the effect of the community-directed treatment (ComDT) approach and the school-based treatment approach on the prevalence and intensity of schistosomiasis and soil-transmitted helminthiasis (STH) among schoolchildren. Following a parasitological survey in a randomly selected sample of 1140 schoolchildren, school-age children in 10 study villages received one dose of praziquantel (40 mg/kg body weight) against schistosomiasis and one dose of albendazole (400mg) against STH. Five of these villages implemented the ComDT approach and received treatment by community drug distributors, while school teachers administered treatment in five other villages using the school-based approach. At 12 months follow-up, the prevalence of Schistosoma mansoni and Trichuris trichiura infections were similar between the ComDT and the school-based approaches when examined in randomly selected schoolchildren (10.1 vs. 9.4%, P=0.66 and 0.8 vs. 1.4%, P=0.37). However, the prevalence of S. haematobium and hookworm infections were significantly lower in the ComDT approach villages compared to the school-based approach villages (10.6 vs. 16.3%, P=0.005 and 2.9 vs. 5.8%, P=0.01, respectively). The results showed that the ComDT approach is at least as effective as the school-based approach in reducing prevalence and intensity of schistosomiasis and STH among schoolchildren.

The unacknowledged impact of chronic schistosomiasis

OBJECTIVES

To summarize new knowledge on the range of disease due to chronic schistosomiasis and examine the debilitating burden of both light and heavy infection; to outline goals of disease prevention, including current age-targeted strategies and more extended programmes aimed at preventing transmission.

METHODS

A systematic search of 2004-2007 papers via PUBMED and related databases using 'schistosom' and disability- or treatment-related subject headings. Reports were independently reviewed for inclusion.

RESULTS

Sixty-eight papers met review objectives. These suggest new evidence for a causative link between schistosome infection, antiparasite inflammation, and risk for anaemia, growth stunting and undernutrition in affected populations, as well as exacerbation of co-infections and impairment of cognitive development and work capacity. Formal quality-of-life assessment defines a significant 9.5-24% disability with the most aggressive schistosome species, Schistosoma japonicum.

DISCUSSION

Schistosomiasis represents a serious but under-recognized disease burden for many developing countries. Infection (and not intensity of infection) should be considered the defining feature of morbidity formation. Links between infection and long-term disabilities reduce the chances of combating rural poverty. Changes in our appreciation of schistosomiasis-related disease burden means it is no longer appropriate to leave infected persons untreated, and newer approaches to control should focus on preventing transmission.

A combined school- and community-based campaign targeting all school-age children of Burkina Faso against schistosomiasis and soil-transmitted helminthiasis: performance, financial costs and implications for sustainability

A combined school- and community-based campaign targeting the entire school-age population of Burkina Faso with drugs against schistosomiasis (praziquantel) and soil-transmitted helminthiasis (albendazole) was implemented in 2004-2005. In total, 3,322,564 children from 5 to 15 years of age were treated, equivalent to a 90.8% coverage of the total school-age population of the country. The total costs of the campaign were estimated to be US 1,067,284 dollars, of which 69.4% was spent on the drugs. Delivery costs per child treated were US 0.098 dollar, in the same range as school-based only interventions implemented in other countries; total costs per child treated (including drugs) were US 0.32 dollar. We conclude that a combined school- and community-based strategy is effective in attaining a high coverage among school-age children in countries where school enrolment is low and where primary schools cannot serve as the exclusive drug distribution points. The challenge for Burkina Faso will now be to ensure the sustainability of these disease control activities.

The cost of delivering and sustaining a control programme for schistosomiasis and soil-transmitted helminthiasis

Large-scale chemotherapy programmes for helminth control continue to rely heavily on donor support. This is despite more than a 10-fold reduction in delivery costs from integrating drug distribution through the school system rather than using mobile teams and a marked decline in the price of albendazole and praziquantel. Even at these low prices (<US dollars 0.25 per child treated with albendazole), it seems that school-based programmes may not be affordable to governments or communities. It is estimated, for instance, that mass albendazole treatment of school-aged children in Kenya could cost over US dollars 3 million each year, which is 4% of current national expenditure on all health care. It has been suggested that a cost retrieval system could help ensure sustainability of these programmes. Some studies have shown that parents may be willing-to-pay for the treatment of their children but the actual amount that could be recovered and the ability of households to pay these amounts is uncertain. Furthermore, the costs incurred in implementing school-based delivery are likely to be much higher than the frequently quoted US dollars 0.03 per child by the Partnership for Child Development (PCD) programmes, as this estimate does not include the 'external costs' for the scientific co-ordinating centre which was responsible for supporting these approaches. Whether these school health programmes could run independently of this system at such a low cost remains to be seen.

Experience with school-based interventions against soil-transmitted helminths and extension of coverage to non-enrolled children

This paper reviews the experience with school-based interventions against soil-transmitted helminths with regard to reduction in prevalence, intensity of infection and morbidity. It also examines the existing experience with coverage of school-based programmes to non-enrolled children. However, as this experience is limited, the paper also seeks to give an overview of the need for school control programmes to include other segments of the community. The experiences from the programmes indicate that treatment should be performed twice or thrice yearly without prior diagnosis, should be school-based and involving schoolteachers assisted by health staff, if possible. The drugs of choice are a single dose of 400 mg albendazole or 500 mg mebendazole. If intensities of Trichuris trichiura or hookworm infections are high, a double or triple dose of one of these drugs could be considered to maximise reduction in intensities. For the benefit of growth and iron status, it should be considered to supplement with iron and other micronutrients. School-based programmes should include non-enrolled school age children and pre-school children, and the system of having 'treatment days' at school, where these groups are invited for treatment, seems to be a promising strategy. While antenatal clinics have been involved in the anthelminthic treatment of pregnant women, they have not covered non-pregnant adolescent girls and women. These could be offered treatment through the 'treatment days' at school mentioned earlier.

Extending anthelminthic coverage to non-enrolled school-age children using a simple and low-cost method

School health programmes are the basis of the strategy defined by WHO to reduce morbidity due to soil-transmitted nematodes and schistosomes in school age populations in developing countries. However, low rates of school enrollment can be a major factor limiting their success. In the present study enrolled children were informed by teachers on the date of the next deworming campaign and were invited to pass along this information to parents, siblings and friends of school-age. On the day of the deworming campaign, teachers were instructed to administer anthelminthics to enrolled and not enrolled school-age children present at school. In the month following the treatment day, information about coverage was collected by questionnaire in 257 households in two regions of Unguja Island, Zanzibar. Over 89% of school age children resulted treated (98.9% of those enrolled plus 60% of those not enrolled). The additional cost of treating non-enrolled is limited to the cost of providing additional doses of anthelminthic drug in each school. Non-enrolled school age children can easily, successfully and inexpensively included in school based deworming campaign. Managers of control programmes are invited to test this method adapting it in their particular and cultural environment.

School enrollment in Zanzibar linked to children's age and helminth infections

School health programmes have been identified as a cost-effective strategy to reduce morbidity due to soil-transmitted helminths in the school-age population, but the low rate of school enrollment in developing countries is a major factor limiting their success.

OBJECTIVE

The present study was conducted to identify reasons for non-enrollment and to evaluate differences in the occurrence of helminth infection between enrolled and non-enrolled children in Zanzibar, United Republic of Tanzania.

METHOD

A questionnaire was submitted to 520 households to obtain information about enrollment and other socio-economic indicators. In addition, one school-age child was randomly selected in each household and investigated for soil-transmitted helminth infection.

RESULTS

Overall, 71% of school-age children were enrolled. Enrollment increased with age. Only 41% of children under 9 years of age were enrolled compared to 91% in children older than 12 years. Enrollment is delayed because of an insufficient number of schools. Among non-enrolled school-age children, the proportion of heavy intensity infections was twice that of enrolled school-age children.

CONCLUSIONS

Most of the non-enrolled school-age children live together with enrolled siblings in the same household, thereby representing an important opportunity for effective outreach activities. The effectiveness of the school-based helminth control programme in reducing the intensity of infection was confirmed. The significant gains achieved by enrolled school-age children in this study must be viewed as an attainable goal for the important numbers of non-enrolled school-age children in endemic areas. Decision-makers must ensure that outreach activities are included in helminth control programmes targeted to school-age children.

Health and cultural factors associated with enrolment in basic education: a study in rural Ghana

This inter-disciplinary study compares the health status of school-age children in Ghana, both enrolled and non-enrolled, and examines these results within a wider socio-economic and socio-cultural context including kinship and livelihood. Children matched for age and sex who were not enrolled in Primary School were significantly shorter and more stunted than enrolled children were, and 70% of all Primary school-age children were anaemic. Young children from farming communities were significantly more undernourished than children from fishing communities. Adolescent non-enrolled boys were more heavily infected with Schistosoma haematobium, and were more likely to be anaemic than enrolled adolescent boys. The data indicate how health and health related factors may influence and affect enrolment and how socio-economic indicators, livelihood, and kinship may also constrain enrolment and, in turn, affect child health. This study sheds light on the complex factors that may influence enrolment in education and provides novel data on the similarities and differences between the health of enrolled and non-enrolled children in rural Ghana.

The health of enrolled and non enrolled children of school age in Tanga, Tanzania

The health of 227 children enrolled at primary school was compared with that of 214 non enrolled children living in rural Tanga, Tanzania. No consistent difference was observed with respect to prevalence and intensity of parasitic infection (hookworm, T. trichiura, A. lumbricoides, S. haematobium and P. falciparum). Since enrolled children were as commonly and as heavily infected as non enrolled children, treatment of enrolled children would be effective in reducing transmission throughout the total population. Non enrolled children were more stunted (P=0.0001) and wasted (P=0.0001) than enrolled children and also tended to be more anaemic (P=0.080) showing that poor nutrition is not only associated with delayed enrolment but continues to be associated with non enrolment throughout the school age years. Given that treatment has the greatest impact on the most malnourished children, additional measures to extend treatment to non enrolled children would be justified.

Hepatic schistosomiasis

Schistosomiasis is a major, worldwide cause of morbidity and mortality. Disease from the organism Schistosoma mansoni results from egg deposition in the liver, intestines, and other organs and is associated with an intense, granulomatous response from the human host. Clinical manifestations range from mild to severe intestinal forms, and hepatosplenic schistosomiasis, which is associated with hepatic fibrosis, portal hypertension, esophageal varices, and splenomegaly. This article presents information about the epidemiology, immunopathogenesis and clinical aspects of the disease, the relationship between hepatic schistosomiasis and viral infections, diagnosis, therapy, and control strategies for schistosomiasis.

The costs and coverage of a strategy to control schistosomiasis morbidity in non-enrolled school-age children in Egypt

Schistosomiasis still constitutes a major public health problem in some endemic parts of rural Egypt, particularly in school-aged children. The school-based health programme for schistosomiasis control adopted by the Egyptian Ministry of Health and Population (MOHP) focuses on treating enrolled schoolchildren. Children who are not enrolled or who do not attend regularly (out-of-school) do not have access to this service, in spite of evidence that the prevalence and intensity of infection are higher in these children than among children who attend school regularly. The aim of the present study was to test an intervention to extend the existing routinely applied school-based treatment to the out-of-school children. This paper reports on the costs and the coverage obtained by the intervention under 2 alternative delivery strategies: selective versus mass chemotherapy for out-of-school children. The intervention reached 88.5% of the out-of-school children at a relatively low cost per infected child of 2.29 L.E. (US$0.67) and 2.02 L.E. (US$0.59) for selective and mass chemotherapy, respectively. The calculations also suggest that, if the government were to implement such a programme, it would be more efficient to offer mass than selective chemotherapy at observed levels of prevalence. Sensitivity analysis showed that selective chemotherapy would be more cost-effective in areas where the prevalence of infection in out-of-school children was < 43%.

Developing strategies to control schistosomiasis morbidity in nonenrolled school-age children: experience from Egypt

Schistosomiasis is a major health problem in school-age children in much of the tropical world. They harbour the most intense infections for both Schistosoma mansoni and S. haematobium. In Egypt, the Ministry of Health and Population (MOHP) has implemented a successful school-based treatment programme in which children are screened and those found to be infected treated with praziquantel. High nonenrolment rates in some rural areas have a negative impact on the coverage of this programme and on its ability to reduce transmission in the community. The main aim of our study was to introduce and test a simple intervention to extend treatment to nonenrolled children using the routine MOHP schistosomiasis treatment programme. Twenty villages or ezbas in Tamia district, Fayoum governorate, with 8 schools and 1901 nonenrolled children were targeted. 88.5% of nonenrolled children attended schools to avail themselves of treatment. Coverage rates were significantly higher for girls (P < 0.001). These results are important for countries where schistosomiasis is endemic. They suggest that offering interventions in schools may not only improve the health of school attendees but also be an affordable way of extending services to out-of-school children.

Schistosomiasis screening and health education for children: action research in Nile delta villages

In Egypt an important component of the national schistosomiasis control policy is the regular screening of school children through the rural health units. In the Nile delta, a major challenge for the programme is the increasing predominance of Schistosoma mansoni, as compared to Schistosoma haematobium over the past 20 years, and the need to adjust strategies to this new reality. The action research project, growing out of an in-depth study of schistosomiasis in two Nile delta villages, is intended to provide recommendations for schistosomiasis control to the Egyptian Ministry of Health and Population. This paper explores the practice of school-based screening. We then describe the designing and testing of a revised screening procedure, which focuses on the collection of stool specimens to diagnose S. mansoni and which is comprehensive and gender-sensitive. Opportunities for health education are discussed briefly, as this is necessary for an effective screening procedure and to prevent reinfection. In conclusion, we mention the need to incorporate screening and health education into an integrated control strategy

The proportion of helminth infections in a community in western Kenya which would be treated by mass chemotherapy of schoolchildren

The present study used data from a community-based epidemiological survey of 752 persons in 3 villages in Kisumu District, western Kenya, to examine the proportion of infected persons who would be treated, as well as the effect on helminth egg production, if anthelmintics were provided to schoolchildren. Overall prevalences of hookworm, Ascaris lumbricoides, Trichuris trichiura and Schistosoma mansoni infections were 63%, 16%, 24% and 24% respectively, and intensities were low for all infections. Only 79% of the school-aged children were enrolled. For all 4 infections, a school-based programme would treat between 76% and 86% of infected school-age children and would theoretically eliminate between 83% and 92% of the number of eggs excreted by this age group. Of the total population, school-based programmes would treat only between 31% and 50% of the infected persons and eliminate only 15%, 46%, 29% and 27% of the total number of hookworm, Ascaris, Trichuris and S. mansoni eggs excreted, respectively. Provided that school attendance rates were high in the study area, school-based programmes would be efficient in improving the helminth infection status of school-aged children. On the other hand, adults, non-enrolled school-aged children and preschool children not offered treatment represented more than half of the helminth-infected persons and they excreted between half and 85% of the total burden of helminth eggs in the area. Hence, mass chemotherapy of schoolchildren would be less effective in the control of at least hookworm and S. mansoni infections in this specific community. There should therefore be a community-based approach to helminth control in combination with a school-based programme.