Deworming and development: asking the right questions, asking the questions right

A positive consequence of the COVID-19 pandemic: how the counterfactual experience of school closures is accelerating a multisectoral response to the treatment of neglected tropical diseases

Global access to deworming treatment is one of the public health success stories of low-income countries in the twenty-first century. Parasitic worm infections are among the most ubiquitous chronic infections of humans, and early success with mass treatment programmes for these infections was the key catalyst for the neglected tropical disease (NTD) agenda. Since the launch of the 'London Declaration' in 2012, school-based deworming programmes have become the world's largest public health interventions. WHO estimates that by 2020, some 3.3 billion school-based drug treatments had been delivered. The success of this approach was brought to a dramatic halt in April 2020 when schools were closed worldwide in response to the COVID-19 pandemic. These closures immediately excluded 1.5 billion children not only from access to education but also from all school-based health services, including deworming. WHO Pulse surveys in 2021 identified NTD treatment as among the most negatively affected health interventions worldwide, second only to mental health interventions. In reaction, governments created a global Coalition with the twin aims of reopening schools and of rebuilding more resilient school-based health systems. Today, some 86 countries, comprising more than half the world's population, are delivering on this response, and school-based coverage of some key school-based programmes exceeds those from January 2020. This paper explores how science, and a combination of new policy and epidemiological perspectives that began in the 1980s, led to the exceptional growth in school-based NTD programmes after 2012, and are again driving new momentum in response to the COVID-19 pandemic. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.

Are current preventive chemotherapy strategies for controlling and eliminating neglected tropical diseases cost-effective?

Neglected tropical diseases (NTDs) remain a significant cause of morbidity and mortality in many low-income and middle-income countries. Several NTDs, namely lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiases (STH) and trachoma, are predominantly controlled by preventive chemotherapy (or mass drug administration), following recommendations set by the WHO. Over one billion people are now treated for NTDs with this strategy per year. However, further investment and increased domestic healthcare spending are urgently needed to continue these programmes. Consequently, it is vital that the cost-effectiveness of preventive chemotherapy is understood. We analyse the current estimates on the cost per disability-adjusted life year (DALY) of the preventive chemotherapy strategies predominantly used for these diseases and identify key evidence gaps that require further research. Overall, the reported estimates show that preventive chemotherapy is generally cost-effective, supporting WHO recommendations. More specifically, the cost per DALY averted estimates relating to community-wide preventive chemotherapy for lymphatic filariasis and onchocerciasis were particularly favourable when compared with other public health interventions. Cost per DALY averted estimates of school-based preventive chemotherapy for schistosomiasis and STH were also generally favourable but more variable. Notably, the broader socioeconomic benefits are likely not being fully captured by the DALYs averted metric. No estimates of cost per DALY averted relating to community-wide mass antibiotic treatment for trachoma were found, highlighting the need for further research. These findings are important for informing global health policy and support the need for continuing NTD control and elimination efforts.

The Broader Economic Value of School Feeding Programs in Low- and Middle-Income Countries: Estimating the Multi-Sectoral Returns to Public Health, Human Capital, Social Protection, and the Local Economy

Introduction: Globally, there are 370 million children receiving school meals every day. Coverage is least in low-income countries, where the need is greatest and where program costs are viewed as high in comparison with the benefits to public health alone. Here we explore the policy implications of including the returns of school feeding to other sectors in an economic analysis.

Methods: We develop an economic evaluation methodology to estimate the costs and benefits of school feeding programs across four sectors: health and nutrition; education; social protection; and the local agricultural economy. We then apply this multi-sectoral benefit-cost analytical framework to school feeding programs in 14 countries (Botswana, Brazil, Cape Verde, Chile, Côte d'Ivoire, Ecuador, Ghana, India, Kenya, Mali, Mexico, Namibia, Nigeria, and South Africa) for which input data are readily available.

Results: Across the 14 countries, we estimate that 190 million schoolchildren benefit from school feeding programs, with total program budgets reaching USD11 billion per year. Estimated annual human capital returns are USD180 billion: USD24 billion from health and nutrition gains, and USD156 billion from education. In addition, school feeding programs offer annual social protection benefits of USD7 billion and gains to local agricultural economies worth USD23 billion.

Conclusions: This multi-sectoral analysis suggests that the overall benefits of school feeding are several times greater than the returns to public health alone, and that the overall benefit-cost ratio of school feeding programs could vary between 7 and 35, with particular sensitivity to the value of local wages. The scale of the findings suggests that school feeding programs are potentially much more cost-beneficial when viewed from the perspective of their multi-sectoral returns, and that it would be worthwhile following up with more detailed analyses at the national level to enhance the precision of these estimates.

Study on the prevalence of intestinal parasitic infections and the assessment of the efficacy of albendazole in soil-transmitted helminths in school-going children in East Sikkim

Background:

The problem of intestinal parasitic infections (IPIs) in children is one of the most worrisome problems worldwide. The latest estimates indicate that more than 880 million children are in the need of treatment for these parasites.

Objective:

The aim of this study was to measure the prevalence of IPIs in school-going children in East Sikkim, India, and to assess the efficacy of single-dose albendazole (ALB) in children infected with soil-transmitted helminths (STHs).

Subjects and Methods:

A total of 300 stool samples were collected from the schoolchildren of government schools of East Sikkim. Samples were processed for the identification of IPIs by direct microscopy and formalin-ether concentration method. Fecal egg counting was carried out for STH by Stoll's egg counting technique, pre- and posttreatment with single-dose ALB. The second stool samples were collected 10–14 days posttreatment of ALB. Cure rate (CR) and the fecal egg reduction rate (ERR), the two most widely used indicators for assessing the efficacy of an anthelmintic, were used in this study. The data were analyzed and the results were interpreted statistically.

Results:

The overall prevalence of the IPIs was 33.9%. Helminthic infection was 4.6% and protozoan infection was 29.3%. Among helminthes Ascaris lumbricoides and among protozoans Entamoeba spp. were the dominant intestinal parasites. For drug efficacy, A. lumbricoides had CR 55.5% and ERR 81.4%. Moreover, for Trichuris trichiura, CR and ERR was 100%. The study has shown less efficacy against A. lumbricoides infections compared to T. trichiura.

Conclusion:

The study provides useful insight into the current prevalence of IPIs in school-going children in government schools in East Sikkim region. Keeping in view of less efficacy of ALB, it is necessary to keep the monitoring of development of drug resistance simultaneously.

Mass deworming for improving health and cognition of children in endemic helminth areas: A systematic review and individual participant data network meta-analysis

Background

Soil transmitted (or intestinal) helminths and schistosomes affect millions of children worldwide.

Objectives

To use individual participant data network meta-analysis (NMA) to explore the effects of different types and frequency of deworming drugs on anaemia, cognition and growth across potential effect modifiers.

Search Methods

We developed a search strategy with an information scientist to search MEDLINE, CINAHL, LILACS, Embase, the Cochrane Library, Econlit, Internet Documents in Economics Access Service (IDEAS), Public Affairs Information Service (PAIS), Social Services Abstracts, Global Health CABI and CAB Abstracts up to March 27, 2018. We also searched grey literature, websites, contacted authors and screened references of relevant systematic reviews.

Selection Criteria

We included randomised and quasirandomised deworming trials in children for deworming compared to placebo or other interventions with data on baseline infection.

Data Collection and Analysis

We conducted NMA with individual participant data (IPD), using a frequentist approach for random-effects NMA. The covariates were: age, sex, weight, height, haemoglobin and infection intensity. The effect estimate chosen was the mean difference for the continuous outcome of interest.

Results

We received data from 19 randomized controlled trials with 31,945 participants. Overall risk of bias was low. There were no statistically significant subgroup effects across any of the potential effect modifiers. However, analyses showed that there may be greater effects on weight for moderate to heavily infected children (very low certainty evidence).

Authors' Conclusions

This analysis reinforces the case against mass deworming at a population-level, finding little effect on nutritional status or cognition. However, children with heavier intensity infections may benefit more. We urge the global community to adopt calls to make data available in open repositories to facilitate IPD analyses such as this, which aim to assess effects for the most vulnerable individuals.

Public health deworming programmes for soil-transmitted helminths in children living in endemic areas

BACKGROUND

The World Health Organization (WHO) recommends treating all school children at regular intervals with deworming drugs in areas where helminth infection is common. Global advocacy organizations claim routine deworming has substantive health and societal effects beyond the removal of worms. In this update of the 2015 edition we included six new trials, additional data from included trials, and addressed comments and criticisms.

OBJECTIVES

To summarize the effects of public health programmes to regularly treat all children with deworming drugs on child growth, haemoglobin, cognition, school attendance, school performance, physical fitness, and mortality.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; Embase; LILACS; the metaRegister of Controlled Trials (mRCT); reference lists; and registers of ongoing and completed trials up to 19 September 2018.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs that compared deworming drugs for soil-transmitted helminths (STHs) with placebo or no treatment in children aged 16 years or less, reporting on weight, height, haemoglobin, and formal tests of cognition. We also sought data on other measures of growth, school attendance, school performance, physical fitness, and mortality.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed the trials for inclusion, risk of bias, and extracted data. We analysed continuous data using the mean difference (MD) with 95% confidence intervals (CIs). Where data were missing, we contacted trial authors. We stratified the analysis based on the background burden of STH infection. We used outcomes at time of longest follow-up. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We identified 51 trials, including 10 cluster-RCTs, that met the inclusion criteria. One trial evaluating mortality included over one million children, and the remaining 50 trials included a total of 84,336 participants. Twenty-four trials were in populations categorized as high burden, including nine trials in children selected because they were helminth-stool positive; 18 with intermediate burden; and nine as low burden.First or single dose of deworming drugsFourteen trials reported on weight after a single dose of deworming drugs (4970 participants, 14 RCTs). The effects were variable. There was little or no effect in studies conducted in low and intermediate worm burden groups. In the high-burden group, there was little or no effect in most studies, except for a large effect detected from one study area in Kenya reported in two trials carried out over 30 years ago. These trials result in qualitative heterogeneity and uncertainty in the meta-analysis across all studies (I² statistic = 90%), with GRADE assessment assessed as very low-certainty, which means we do not know if a first dose or single dose of deworming impacts on weight.For height, most studies showed little or no effect after a single dose, with one of the two trials in Kenya from 30 years ago showing a large average difference (2621 participants, 10 trials, low-certainty evidence). Single dose probably had no effect on average haemoglobin (MD 0.10 g/dL, 95% CI 0.03 lower to 0.22 higher; 1252 participants, five trials, moderate-certainty evidence), or on average cognition (1596 participants, five trials, low-certainty evidence). The data are insufficient to know if there is an effect on school attendance and performance (304 participants, one trial, low-certainty evidence), or on physical fitness (280 participants, three trials, very low-certainty evidence). No trials reported on mortality.Multiple doses of deworming drugsThe effect of regularly treating children with deworming drugs given every three to six months on weight was reported in 18 trials, with follow-up times of between six months and three years; there was little or no effect on average weight in all but two trials, irrespective of worm prevalence-intensity. The two trials with large average weight gain included one in the high burden area in Kenya carried out over 30 years ago, and one study from India in a low prevalence area where subsequent studies in the same area did not show an effect. This heterogeneity causes uncertainty in any meta-analysis (I² = 78%). Post-hoc analysis excluding trials published prior to 2000 gave an estimate of average difference in weight gain of 0.02 kg (95%CI from 0.04 kg loss to 0.08 gain, I² = 0%). Thus we conclude that we do not know if repeated doses of deworming drugs impact on average weight, with a fewer older studies showing large gains, and studies since 2000 showing little or no average gain.Regular treatment probably had little or no effect on the following parameters: average height (MD 0.02 cm higher, 95% CI 0.09 lower to 0.13 cm higher; 13,700 participants, 13 trials, moderate-certainty evidence); average haemoglobin (MD 0.01 g/dL lower; 95% CI 0.05 g/dL lower to 0.07 g/dL higher; 5498 participants, nine trials, moderate-certainty evidence); formal tests of cognition (35,394 participants, 8 trials, moderate-certainty evidence); school performance (34,967 participants, four trials, moderate-certainty evidence). The evidence assessing an effect on school attendance is inconsistent, and at risk of bias (mean attendance 2% higher, 95% CI 5% lower to 8% higher; 20,650 participants, three trials, very low-certainty evidence). No trials reported on physical fitness. No effect was shown on mortality (1,005,135 participants, three trials, low-certainty evidence).

AUTHORS' CONCLUSIONS

Public health programmes to regularly treat all children with deworming drugs do not appear to improve height, haemoglobin, cognition, school performance, or mortality. We do not know if there is an effect on school attendance, since the evidence is inconsistent and at risk of bias, and there is insufficient data on physical fitness. Studies conducted in two settings over 20 years ago showed large effects on weight gain, but this is not a finding in more recent, larger studies. We would caution against selecting only the evidence from these older studies as a rationale for contemporary mass treatment programmes as this ignores the recent studies that have not shown benefit.The conclusions of the 2015 edition have not changed in this update.

Sanitation, Disease Externalities and Anaemia: Evidence From Nepal

Anaemia impairs physical and cognitive development in children and reduces human capital accumulation. The prior economics literature has focused on the role of inadequate nutrition in causing anaemia. This article is the first to show that sanitation, a public good, significantly contributes to preventing anaemia. We identify effects by exploiting rapid and differential improvement in sanitation across regions of Nepal between 2006 and 2011. Within regions over time, cohorts of children exposed to better community sanitation developed higher haemoglobin levels. Our results highlight a previously undocumented externality of open defaecation, which is today practiced by over a billion people worldwide.

A life without worms

Worms have co-evolved with humans over millions of years. To survive, they manipulate host systems by modulating immune responses so that they cause (in the majority of hosts) relatively subtle harm. Anthelminthic treatment has been promoted as a measure for averting worm specific pathology and to mitigate subtle morbidities which may include effects on anaemia, growth, cognitive function and economic activity. With our changing environment marked by rapid population growth, urbanisation, better hygiene practices and anthelminthic treatment, there has been a decline in worm infections and other infectious diseases and a rise in non-communicable diseases such as allergy, diabetes and cardiovascular disease. This review reflects upon our age-old interaction with worms, and the broader ramifications of life without worms for vaccine responses and susceptibility to other infections, and for allergy-related and metabolic disease. We touch upon the controversy around the benefits of mass drug administration for the more-subtle morbidities that have been associated with worm infections and then focus our attention on broader, additional aspects of life without worms, which may be either beneficial or detrimental.

Mass deworming to improve developmental health and wellbeing of children in low-income and middle-income countries: a systematic review and network meta-analysis

BACKGROUND

Soil-transmitted helminthiasis and schistosomiasis, considered among the neglected tropical diseases by WHO, affect more than a third of the world's population, with varying intensity of infection. We aimed to evaluate the effects of mass deworming for soil-transmitted helminths (with or without deworming for schistosomiasis or co-interventions) on growth, educational achievement, cognition, school attendance, quality of life, and adverse effects in children in endemic helminth areas.

METHODS

We searched 11 databases up to Jan 14, 2016, websites and trial registers, contacted authors, and reviewed reference lists. We included studies published in any language of children aged 6 months to 16 years, with mass deworming for soil-transmitted helminths or schistosomiasis (alone or in combination with other interventions) for 4 months or longer, that reported the primary outcomes of interest. We included randomised and quasi-randomised trials, controlled before-after studies, interrupted time series, and quasi-experimental studies. We screened in duplicate, then extracted data and appraised risk of bias in duplicate with a pre-tested form. We conducted random-effects meta-analysis and Bayesian network meta-analysis.

FINDINGS

We included 52 studies of duration 5 years or less with 1 108 541 children, and four long-term studies 8-10 years after mass deworming programmes with more than 160 000 children. Overall risk of bias was moderate. Mass deworming for soil-transmitted helminths compared with controls led to little to no improvement in weight over a period of about 12 months (0·99 kg, 95% credible interval [CrI] -0·09 to 0·28; moderate certainty evidence) or height (0·07 cm, 95% CrI -0·10 to 0·24; moderate certainty evidence), little to no difference in proportion stunted (eight fewer per 1000 children, 95% CrI -48 to 32; high certainty evidence), cognition measured by short-term attention (-0·23 points on a 100 point scale, 95% CI -0·56 to 0·14; high certainty evidence), school attendance (1% higher, 95% CI -1 to 3; high certainty evidence), or mortality (one fewer per 1000 children, 95% CI -3 to 1; high certainty evidence). We found no data on quality of life and little evidence of adverse effects. Mass deworming for schistosomiasis might slightly increase weight (0·41 kg, 95% CrI -0·20 to 0·91) and has little to no effect on height (low certainty evidence) and cognition (moderate certainty evidence). Our analyses do not suggest indirect benefits for untreated children from being exposed to treated children in the community. We are uncertain about effects on long-term economic productivity (hours worked), cognition, literacy, and school enrolment owing to very low certainty evidence. Results were consistent across sensitivity and subgroup analyses by age, worm prevalence, baseline nutritional status, infection status, impact on worms, infection intensity, types of worms (ascaris, hookworm, or trichuris), risk of bias, cluster versus individual trials, compliance, and attrition.

INTERPRETATION

Mass deworming for soil-transmitted helminths with or without deworming for schistosomiasis had little effect. For schistosomiasis, mass deworming might be effective for weight but is probably ineffective for height, cognition, and attendance. Future research should assess which subset of children do benefit from mass deworming, if any, using individual participant data meta-analysis.

FUNDING

Canadian Institutes of Health Research and WHO.

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.

[Profiles of intestinal polyparasitism in a community of the Colombian Amazon region]

INTRODUCTION

Intestinal parasite infections and polyparasitism are highly prevalent in the most vulnerable populations of developing countries due to environmental, biological and social determinants common in the transmission of parasites. Children between 1 and 15 years of age are the most affected population.

OBJECTIVE

To describe the prevalence and profiles of intestinal polyparasitism in 1 to 15 year-old children from native communities in the Colombian Amazon region.

MATERIALS AND METHODS

We used a non-probability sampling of 300 children between 1 and 15 years of age from several rural settlements and the main urban area of Puerto Nariño, Amazonas, Colombia, who participated voluntarily in the study. We obtained fecal samples that were analyzed by the direct method (0.85% saline solution-lugol) and the Kato-Katz technique. The most prevalent polyparasitism profiles were identified using Cohen's kappa coefficient with a 95% confidence interval.

RESULTS

The prevalence of polyparasitism, defined as the presence of at least two intestinal pathogenic parasites, was 84% (95 % CI: 79.35-87.96). Polyparasitism by two or three of the following parasites: Ascaris lumbricoides, Trichuris trichiura, Blastocystis sp., Ancylostoma duodenale and Necator americanus from the Ancylostomatidae family, and Entamoeba histolytica, E. dispar and E. moshkovskii of the Entamoeba complex, had the highest prevalence.

CONCLUSION

Several intestinal polyparasitism profiles were found, although in most cases fewer than six parasites were involved. Better prevalence estimations and identification of determinant factors will allow to priorize and direct resources to control these infections.

The cross-cutting contribution of the end of neglected tropical diseases to the sustainable development goals

The Sustainable Development Goals (SDGs) call for an integrated response, the kind that has defined Neglected Tropical Diseases (NTDs) efforts in the past decade.NTD interventions have the greatest relevance for SDG3, the health goal, where the focus on equity, and its commitment to reaching people in need of health services, wherever they may live and whatever their circumstances, is fundamentally aligned with the target of Universal Health Coverage. NTD interventions, however, also affect and are affected by many of the other development areas covered under the 2030 Agenda. Strategies such as mass drug administration or the programmatic integration of NTD and WASH activities (SDG6) are driven by effective global partnerships (SDG17). Intervention against the NTDs can also have an impact on poverty (SDG1) and hunger (SDG2), can improve education (SDG4), work and economic growth (SDG8), thereby reducing inequalities (SDG10). The community-led distribution of donated medicines to more than 1 billion people reinforces women's empowerment (SDG5), logistics infrastructure (SDG9) and non-discrimination against disability (SDG16). Interventions to curb mosquito-borne NTDs contribute to the goals of urban sustainability (SDG11) and resilience to climate change (SDG13), while the safe use of insecticides supports the goal of sustainable ecosystems (SDG15). Although indirectly, interventions to control water- and animal-related NTDs can facilitate the goals of small-scale fishing (SDG14) and sustainable hydroelectricity and biofuels (SDG7).NTDs proliferate in less developed areas in countries across the income spectrum, areas where large numbers of people have little or no access to adequate health care, clean water, sanitation, housing, education, transport and information. This scoping review assesses how in this context, ending the epidemic of the NTDs can impact and improve our prospects of attaining the SDGs.

The Socioeconomic Benefit to Individuals of Achieving the 2020 Targets for Five Preventive Chemotherapy Neglected Tropical Diseases

BACKGROUND

Lymphatic filariasis (LF), onchocerciasis, schistosomiasis, soil-transmitted helminths (STH) and trachoma represent the five most prevalent neglected tropical diseases (NTDs). They can be controlled or eliminated by means of safe and cost-effective interventions delivered through programs of Mass Drug Administration (MDA)-also named Preventive Chemotherapy (PCT). The WHO defined targets for NTD control/elimination by 2020, reinforced by the 2012 London Declaration, which, if achieved, would result in dramatic health gains. We estimated the potential economic benefit of achieving these targets, focusing specifically on productivity and out-of-pocket payments.

METHODS

Productivity loss was calculated by combining disease frequency with productivity loss from the disease, from the perspective of affected individuals. Productivity gain was calculated by deducting the total loss expected in the target achievement scenario from the loss in a counterfactual scenario where it was assumed the pre-intervention situation in 1990 regarding NTDs would continue unabated until 2030. Economic benefits from out-of-pocket payments (OPPs) were calculated similarly. Benefits are reported in 2005 US$ (purchasing power parity-adjusted and discounted at 3% per annum from 2010). Sensitivity analyses were used to assess the influence of changes in input parameters.

RESULTS

The economic benefit from productivity gain was estimated to be I$251 billion in 2011-2020 and I$313 billion in 2021-2030, considerably greater than the total OPPs averted of I$0.72 billion and I$0.96 billion in the same periods. The net benefit is expected to be US$ 27.4 and US$ 42.8 for every dollar invested during the same periods. Impact varies between NTDs and regions, since it is determined by disease prevalence and extent of disease-related productivity loss.

CONCLUSION

Achieving the PCT-NTD targets for 2020 will yield significant economic benefits to affected individuals. Despite large uncertainty, these benefits far exceed the investment required by governments and their development partners within all reasonable scenarios. Given the concentration of the NTDs among the poorest households, these investments represent good value for money in efforts to share the world's prosperity and reduce inequity.

Menstrual cups and sanitary pads to reduce school attrition, and sexually transmitted and reproductive tract infections: a cluster randomised controlled feasibility study in rural Western Kenya

OBJECTIVES

Conduct a feasibility study on the effect of menstrual hygiene on schoolgirls' school and health (reproductive/sexual) outcomes.

DESIGN

3-arm single-site open cluster randomised controlled pilot study.

SETTING

30 primary schools in rural western Kenya, within a Health and Demographic Surveillance System.

PARTICIPANTS

Primary schoolgirls 14-16 years, experienced 3 menses, no precluding disability, and resident in the study area.

INTERVENTIONS

1 insertable menstrual cup, or monthly sanitary pads, against 'usual practice' control. All participants received puberty education preintervention, and hand wash soap during intervention. Schools received hand wash soap.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary: school attrition (drop-out, absence); secondary: sexually transmitted infection (STI) (Trichomonas vaginalis, Chlamydia trachomatis, Neisseria gonorrhoea), reproductive tract infection (RTI) (bacterial vaginosis, Candida albicans); safety: toxic shock syndrome, vaginal Staphylococcus aureus.

RESULTS

Of 751 girls enrolled 644 were followed-up for a median of 10.9 months. Cups or pads did not reduce school dropout risk (control=8.0%, cups=11.2%, pads=10.2%). Self-reported absence was rarely reported and not assessable. Prevalence of STIs in the end-of-study survey among controls was 7.7% versus 4.2% in the cups arm (adjusted prevalence ratio (aPR) 0.48, 0.24 to 0.96, p=0.039), 4.5% with pads (aPR=0.62; 0.37 to 1.03, p=0.063), and 4.3% with cups and pads pooled (aPR=0.54, 0.34 to 0.87, p=0.012). RTI prevalence was 21.5%, 28.5% and 26.9% among cup, pad and control arms, 71% of which were bacterial vaginosis, with a prevalence of 14.6%, 19.8% and 20.5%, per arm, respectively. Bacterial vaginosis was less prevalent in the cups (12.9%) compared with pads (20.3%, aPR=0.65, 0.44 to 0.97, p=0.034) and control (19.2%, aPR=0.67, 0.43 to 1.04, p=0.075) arm girls enrolled for 9 months or longer. No adverse events were identified.

CONCLUSIONS

Provision of menstrual cups and sanitary pads for ∼1 school-year was associated with a lower STI risk, and cups with a lower bacterial vaginosis risk, but there was no association with school dropout. A large-scale trial on menstrual cups is warranted.

TRIAL REGISTRATION

ISRCTN17486946; Results.

Worms at Work: Long-run Impacts of a Child Health Investment

This study estimates long-run impacts of a child health investment, exploiting community-wide experimental variation in school-based deworming. The program increased labor supply among men and education among women, with accompanying shifts in labor market specialization. Ten years after deworming treatment, men who were eligible as boys stay enrolled for more years of primary school, work 17% more hours each week, spend more time in nonagricultural self-employment, are more likely to hold manufacturing jobs, and miss one fewer meal per week. Women who were in treatment schools as girls are approximately one quarter more likely to have attended secondary school, halving the gender gap. They reallocate time from traditional agriculture into cash crops and nonagricultural self-employment. We estimate a conservative annualized financial internal rate of return to deworming of 32%, and show that mass deworming may generate more in future government revenue than it costs in subsidies.

Complexities and Perplexities: A Critical Appraisal of the Evidence for Soil-Transmitted Helminth Infection-Related Morbidity

BACKGROUND

Soil-transmitted helminths (STH) have acute and chronic manifestations, and can result in lifetime morbidity. Disease burden is difficult to quantify, yet quantitative evidence is required to justify large-scale deworming programmes. A recent Cochrane systematic review, which influences Global Burden of Disease (GBD) estimates for STH, has again called into question the evidence for deworming benefit on morbidity due to STH. In this narrative review, we investigate in detail what the shortfalls in evidence are.

METHODOLOGY/PRINCIPAL FINDINGS

We systematically reviewed recent literature that used direct measures to investigate morbidity from STH and we critically appraised systematic reviews, particularly the most recent Cochrane systematic review investigating deworming impact on morbidity. We included six systematic reviews and meta-analyses, 36 literature reviews, 44 experimental or observational studies, and five case series. We highlight where evidence is insufficient and where research needs to be directed to strengthen morbidity evidence, ideally to prove benefits of deworming.

CONCLUSIONS/SIGNIFICANCE

Overall, the Cochrane systematic review and recent studies indicate major shortfalls in evidence for direct morbidity. However, it is questionable whether the systematic review methodology should be applied to STH due to heterogeneity of the prevalence of different species in each setting. Urgent investment in studies powered to detect direct morbidity effects due to STH is required.

Antihelminthics in helminth-endemic areas: effects on HIV disease progression

BACKGROUND

Helminth infections, such as soil-transmitted helminths, schistosomiasis, onchocerciasis, and lymphatic filariasis, are prevalent in many countries where human immunodeficiency virus (HIV) infection is also common. There is some evidence from observational studies that HIV and helminth co-infection may be associated with higher viral load and lower CD4+ cell counts. Treatment of helminth infections with antihelminthics (deworming drugs) may have benefits for people living with HIV beyond simply clearance of worm infections.This is an update of a Cochrane Review published in 2009 and we have expanded it to include outcomes of anaemia and adverse events.

OBJECTIVES

To evaluate the effects of deworming drugs (antihelminthic therapy) on markers of HIV disease progression, anaemia, and adverse events in children and adults.

SEARCH METHODS

In this review update, we searched online for published and unpublished studies in the Cochrane Library, MEDLINE, EMBASE, CENTRAL, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICRTP), ClinicalTrials.gov, and the WHO Global Health Library up to 29 September 2015. We also searched databases listing conference abstracts, scanned reference lists of articles, and contacted the authors of included studies.

SELECTION CRITERIA

We searched for randomized controlled trials (RCTs) that compared antihelminthic drugs with placebo or no intervention in HIV-positive people.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trials for eligibility and risk of bias. The primary outcomes were changes in HIV viral load and CD4+ cell count, and secondary outcomes were anaemia, iron deficiency, adverse events, and mortality events. We compared the effects of deworming using mean differences, risk ratios (RR), and 95% confidence intervals (CIs). We assessed the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Eight trials met the inclusion criteria of this review, enrolling a total of 1612 participants. Three trials evaluated the effect of providing antihelminthics to all adults with HIV without knowledge of their helminth infection status, and five trials evaluated the effects of providing deworming drugs to HIV-positive individuals with confirmed helminth infections. Seven trials were conducted in sub-Saharan Africa and one in Thailand. Antihelminthics for people with unknown helminth infection statusProviding antihelminthics (albendazole and praziquantel together or separately) to HIV-positive adults with unknown helminth infection status may have a small suppressive effect on mean viral load at six weeks but the 95% CI includes the possibility of no effect (difference in mean change -0.14 log10 viral RNA/mL, 95% CI -0.35 to 0.07, P = 0.19; one trial, 166 participants, low quality evidence).Repeated dosing with deworming drugs over two years (albendazole every three months plus annual praziquantel), probably has little or no effect on mean viral load (difference in mean change 0.01 log10 viral RNA, 95% CI: -0.03 to -0.05; one trial, 917 participants, moderate quality evidence), and little or no effect on mean CD4+ count (difference in mean change 2.60 CD4+ cells/µL, 95% CI -10.15 to 15.35; P = 0.7; one trial, 917 participants, low quality evidence). Antihelminthics for people with confirmed helminth infectionsTreating confirmed helminth infections in HIV-positive adults may have a small suppressive effect on mean viral load at six to 12 weeks following deworming (difference in mean change -0.13 log10 viral RNA, 95% CI -0.26 to -0.00; P = 0.04; four trials, 445 participants, low quality evidence). However, this finding is strongly influenced by a single study of praziquantel treatment for schistosomiasis. There may also be a small favourable effect on mean CD4+ cell count at 12 weeks after deworming in HIV-positive populations with confirmed helminth infections (difference in mean change 37.86 CD4+ cells/µL, 95% CI 7.36 to 68.35; P = 0.01; three trials, 358 participants, low quality evidence). Adverse events and mortality There is no indication that antihelminthic drugs impart additional risks in HIV-positive populations. However, adverse events were not well reported (very low quality evidence) and trials were underpowered to evaluate effects on mortality (low quality evidence).

AUTHORS' CONCLUSIONS

There is low quality evidence that treating confirmed helminth infections in HIV-positive adults may have small, short-term favourable effects on markers of HIV disease progression. Further studies are required to confirm this finding. Current evidence suggests that deworming with antihelminthics is not harmful, and this is reassuring for the routine treatment of confirmed or suspected helminth infections in people living with HIV in co-endemic areas.Further long-term studies are required to make confident conclusions regarding the impact of presumptively deworming all HIV-positive individuals irrespective of helminth infection status, as the only long-term trial to date did not demonstrate an effect.

Knowledge gaps in the epidemiology of Toxocara: the enigma remains

Toxocara species infect a wide range of companion, domestic and wild animals as definitive and paratenic hosts, via multiple routes of transmission, producing long-lived tissue-inhabiting larvae and resistant eggs that can survive in the external environment. Therefore Toxocara and the disease it causes in humans, toxocariasis, represents an ideal aetiological agent for the development of the one health approach. However, despite increasing awareness of the public health significance of toxocariasis, gaps in our understanding of certain key aspects of the parasite's biology and epidemiology remain. These gaps hinder our ability to integrate research effort within the veterinary, medical and environmental disciplines. This review will highlight key deficits in our understanding of nine dimensions of Toxocara epidemiology and discuss a potential scenario to develop a more integrated, one health approach to improve our understanding of the prevention and control of this complex and cryptic zoonosis.

Cerebral Toxocariasis: Silent Progression to Neurodegenerative Disorders?

Toxocara canis and T. cati are highly prevalent nematode infections of the intestines of dogs and cats. In paratenic hosts, larvae do not mature in the intestine but instead migrate through the somatic tissues and organs of the body. The presence of these migrating larvae can contribute to pathology. Toxocara larvae can invade the brains of humans, and while case descriptions of cerebral toxocariasis are historically rare, improved diagnosis and greater awareness have contributed to increased detection. Despite this, cerebral or neurological toxocariasis (NT) remains a poorly understood phenomenon. Furthermore, our understanding of cognitive deficits due to toxocariasis in human populations remains particularly deficient. Recent data describe an enhanced expression of biomarkers associated with brain injury, such as GFAP, AβPP, transforming growth factor β1 (TGF-β1), NF-L, S100B, tTG, and p-tau, in mice receiving even low doses of Toxocara ova. Finally, this review outlines a hypothesis to explore the relationship between the presence of T. canis larvae in the brain and the progression of Alzheimer's disease (AD) due to enhanced AD-associated neurodegenerative biomarker expression.

Deworming drugs for soil-transmitted intestinal worms in children: effects on nutritional indicators, haemoglobin, and school performance

BACKGROUND

The World Health Organization (WHO) recommends treating all school children at regular intervals with deworming drugs in areas where helminth infection is common. As the intervention is often claimed to have important health, nutrition, and societal effects beyond the removal of worms, we critically evaluated the evidence on benefits.

OBJECTIVES

To summarize the effects of giving deworming drugs to children to treat soil-transmitted helminths on weight, haemoglobin, and cognition; and the evidence of impact on physical well-being, school attendance, school performance, and mortality.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register (14 April 2015); Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library (2015, Issue 4); MEDLINE (2000 to 14 April 2015); EMBASE (2000 to 14 April 2015); LILACS (2000 to 14 April 2015); the metaRegister of Controlled Trials (mRCT); and reference lists, and registers of ongoing and completed trials up to 14 April 2015.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs comparing deworming drugs for soil-transmitted helminths with placebo or no treatment in children aged 16 years or less, reporting on weight, haemoglobin, and formal tests of intellectual development. We also sought data on school attendance, school performance, and mortality. We included trials that combined health education with deworming programmes.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed the trials, evaluated risk of bias, and extracted data. We analysed continuous data using the mean difference (MD) with 95% confidence intervals (CIs). Where data were missing, we contacted trial authors. We used outcomes at time of longest follow-up. The evidence quality was assessed using GRADE. This edition of the Cochrane Review adds the DEVTA trial from India, and draws on an independent analytical replication of a trial from Kenya.

MAIN RESULTS

We identified 45 trials, including nine cluster-RCTs, that met the inclusion criteria. One trial evaluating mortality included over one million children, and the remaining 44 trials included a total of 67,672 participants. Eight trials were in children known to be infected, and 37 trials were carried out in endemic areas, including areas of high (15 trials), moderate (12 trials), and low prevalence (10 trials). Treating children known to be infectedTreating children known to be infected with a single dose of deworming drugs (selected by screening, or living in areas where all children are infected) may increase weight gain over the next one to six months (627 participants, five trials, low quality evidence). The effect size varied across trials from an additional 0.2 kg gain to 1.3 kg. There is currently insufficient evidence to know whether treatment has additional effects on haemoglobin (247 participants, two trials, very low quality evidence); school attendance (0 trials); cognitive functioning (103 participants, two trials, very low quality evidence), or physical well-being (280 participants, three trials, very low quality evidence). Community deworming programmesTreating all children living in endemic areas with a dose of deworming drugs probably has little or no effect on average weight gain (MD 0.04 kg less, 95% CI 0.11 kg less to 0.04 kg more; trials 2719 participants, seven trials, moderate quality evidence), even in settings with high prevalence of infection (290 participants, two trials). A single dose also probably has no effect on average haemoglobin (MD 0.06 g/dL, 95% CI -0.05 lower to 0.17 higher; 1005 participants, three trials, moderate quality evidence), or average cognition (1361 participants, two trials, low quality evidence).Similiarly, regularly treating all children in endemic areas with deworming drugs, given every three to six months, may have little or no effect on average weight gain (MD 0.08 kg, 95% CI 0.11 kg less to 0.27 kg more; 38,392 participants, 10 trials, low quality evidence). The effects were variable across trials; one trial from a low prevalence setting carried out in 1995 found an increase in weight, but nine trials carried out since then found no effect, including five from moderate and high prevalence areas.There is also reasonable evidence that regular treatment probably has no effect on average height (MD 0.02 cm higher, 95% CI 0.14 lower to 0.17 cm higher; 7057 participants, seven trials, moderate quality evidence); average haemoglobin (MD 0.02 g/dL lower; 95% CI 0.08 g/dL lower to 0.04 g/dL higher; 3595 participants, seven trials, low quality evidence); formal tests of cognition (32,486 participants, five trials, moderate quality evidence); exam performance (32,659 participants, two trials, moderate quality evidence); or mortality (1,005,135 participants, three trials, low quality evidence). There is very limited evidence assessing an effect on school attendance and the findings are inconsistent, and at risk of bias (mean attendance 2% higher, 95% CI 4% lower to 8% higher; 20,243 participants, two trials, very low quality evidence).In a sensitivity analysis that only included trials with adequate allocation concealment, there was no evidence of any effect for the main outcomes.

AUTHORS' CONCLUSIONS

Treating children known to have worm infection may have some nutritional benefits for the individual. However, in mass treatment of all children in endemic areas, there is now substantial evidence that this does not improve average nutritional status, haemoglobin, cognition, school performance, or survival.

Multiparasitism and intensity of helminth infections in relation to symptoms and nutritional status among children: a cross-sectional study in southern Lao People's Democratic Republic

The occurrence and spatial distribution of intestinal helminth infection in children is fairly well understood. However, knowledge on how helminth infections govern intestinal morbidity is scarce. We conducted a cross-sectional study to assess and quantify the relationship between single and multiple species helminth infection with clinical and self-reported morbidity indicators and nutritional status in Champasack province, southern Lao People's Democratic Republic (Lao PDR). A random sample of 1313 children, aged 6 months to 12 years, from villages in nine rural districts were enrolled and examined for helminth infection using duplicate Kato-Katz thick smears. Morbidity was assessed by self-reported symptoms, coupled with clinical examination and appraisal of nutritional status and anaemia. Bivariate and multivariate logistic regression was employed to study associations between helminth infection and morbidity indicators and anaemia. We found considerable morbidity among the surveyed children, including hepatomegaly (13.7%), pale conjunctiva (13.2%) and abdominal pain (10.4%). Anaemia was recorded in 60.4% of the children, whilst signs of stunting and low body mass index (BMI) were observed in 49.8% and 33.3% of the surveyed children, respectively. Hookworm and Opisthorchis viverrini were the predominant helminth species with prevalences of 51.0% and 43.3%, respectively. The prevalence of Schistosoma mekongi in the surveyed children was 5.6%. Multiple species helminth infections were recorded in 40.4% of the study cohort. Morbidity was associated with specific helminth species infection (e.g. S. mekongi with hepatomegaly; adjusted odds ratio (aOR): 9.49, 95% confidence interval (CI): 2.07-43.51) and multiparasitism (e.g. two or more helminth species with abdominal pain; aOR: 2.40, 95% CI: 1.46-3.93). Anaemia was associated with hookworm infection (aOR: 1.64, 95% CI: 1.16-2.34) and multiparasitism (aOR: 1.64, 95% CI: 1.18-2.29). Low BMI was associated with O. viverrini infection (aOR: 1.68, 95% CI: 1.14-2.49) and multiparasitism (aOR: 1.42, 95% CI: 1.01-2.00). The multiple strong associations reported here between helminth infections (single or multiple species) and intestinal morbidity among children in rural parts of southern Lao PDR call for concerted efforts to control helminth infections, which in turn might improve children's health and development.

Geographical inequalities in use of improved drinking water supply and sanitation across Sub-Saharan Africa: mapping and spatial analysis of cross-sectional survey data

BACKGROUND

Understanding geographic inequalities in coverage of drinking-water supply and sanitation (WSS) will help track progress towards universal coverage of water and sanitation by identifying marginalized populations, thus helping to control a large number of infectious diseases. This paper uses household survey data to develop comprehensive maps of WSS coverage at high spatial resolution for sub-Saharan Africa (SSA). Analysis is extended to investigate geographic heterogeneity and relative geographic inequality within countries.

METHODS AND FINDINGS

Cluster-level data on household reported use of improved drinking-water supply, sanitation, and open defecation were abstracted from 138 national surveys undertaken from 1991-2012 in 41 countries. Spatially explicit logistic regression models were developed and fitted within a Bayesian framework, and used to predict coverage at the second administrative level (admin2, e.g., district) across SSA for 2012. Results reveal substantial geographical inequalities in predicted use of water and sanitation that exceed urban-rural disparities. The average range in coverage seen between admin2 within countries was 55% for improved drinking water, 54% for use of improved sanitation, and 59% for dependence upon open defecation. There was also some evidence that countries with higher levels of inequality relative to coverage in use of an improved drinking-water source also experienced higher levels of inequality in use of improved sanitation (rural populations r = 0.47, p = 0.002; urban populations r = 0.39, p = 0.01). Results are limited by the quantity of WSS data available, which varies considerably by country, and by the reliability and utility of available indicators.

CONCLUSIONS

This study identifies important geographic inequalities in use of WSS previously hidden within national statistics, confirming the necessity for targeted policies and metrics that reach the most marginalized populations. The presented maps and analysis approach can provide a mechanism for monitoring future reductions in inequality within countries, reflecting priorities of the post-2015 development agenda. Please see later in the article for the Editors' Summary.

Effects of geohelminth infections on neurological development

Published reviews vary on the question of whether geohelminth infections affect cognitive development: some claim that the scarcity of evidence means that it is unlikely that they do; others present modest evidence for an effect; and others raise the possibility that the damage is considerable but largely unresearched. This chapter reviews the characteristics of the geohelminths themselves and the pathways by which they could affect the development of children in endemic areas. It describes the progress made in the last decade in conceptualizing children's brains as complex adaptive systems, with the suggestion that infections at different stages in brain development might have different neurobehavioral consequences. An examination of research reports and review articles highlights the difficulties inherent in assessing the effects of geohelminth infections: other serious obstacles to healthy development in the same population may mask the effects of the geohelminths, and consequently the intensity and pathogenicity of the infection is probably an important issue. Selecting cognitive measures suitable for assessing development in very young children is no simple matter, and careful statistical analysis is required to tease out the primary and secondary factors at work. The insights gained from a broad range of relevant research reports have placed us in a better position to conduct more telling research into the effects of these widespread, but neglected, tropical diseases.

Global numbers of infection and disease burden of soil transmitted helminth infections in 2010

BACKGROUND

Quantifying the burden of parasitic diseases in relation to other diseases and injuries requires reliable estimates of prevalence for each disease and an analytic framework within which to estimate attributable morbidity and mortality. Here we use data included in the Global Atlas of Helminth Infection to derive new global estimates of numbers infected with intestinal nematodes (soil-transmitted helminths, STH: Ascaris lumbricoides, Trichuris trichiura and the hookworms) and use disability-adjusted life years (DALYs) to estimate disease burden.

METHODS

Prevalence data for 6,091 locations in 118 countries were sourced and used to estimate age-stratified mean prevalence for sub-national administrative units via a combination of model-based geostatistics (for sub-Saharan Africa) and empirical approaches (for all other regions). Geographical variation in infection prevalence within these units was approximated using modelled logit-normal distributions, and numbers of individuals with infection intensities above given thresholds estimated for each species using negative binomial distributions and age-specific worm/egg burden thresholds. Finally, age-stratified prevalence estimates for each level of infection intensity were incorporated into the Global Burden of Disease Study 2010 analytic framework to estimate the global burden of morbidity and mortality associated with each STH infection.

RESULTS

Globally, an estimated 438.9 million people (95% Credible Interval (CI), 406.3 - 480.2 million) were infected with hookworm in 2010, 819.0 million (95% CI, 771.7 - 891.6 million) with A. lumbricoides and 464.6 million (95% CI, 429.6 - 508.0 million) with T. trichiura. Of the 4.98 million years lived with disability (YLDs) attributable to STH, 65% were attributable to hookworm, 22% to A. lumbricoides and the remaining 13% to T. trichiura. The vast majority of STH infections (67%) and YLDs (68%) occurred in Asia. When considering YLDs relative to total populations at risk however, the burden distribution varied more considerably within major global regions than between them.

CONCLUSION

Improvements in the cartography of helminth infection, combined with mathematical modelling approaches, have resulted in the most comprehensive contemporary estimates for the public health burden of STH. These numbers form an important benchmark upon which to evaluate future scale-up of major control efforts.

Early childhood malaria prevention and children's patterns of school leaving in the Gambia

BACKGROUND

Early childhood malaria is often fatal, but its impact on the development and education of survivors has not received much attention. Malaria impacts cognitive development in a number of ways that may impact later educational participation.

AIMS

In this study, we examine the long-term educational effects of preventing early childhood malaria. Does intermittent preventive treatment (IPT) during early childhood reduce the risk of dropout? If so, does this effect vary by school type - government school versus madrassa?

SAMPLE

We use data from a 2001 follow-up of a 1985-1987 malaria prevention randomized controlled trial in the Gambia. The sample consists of 562 youth born between 1981 and 1986.

METHODS

We use discrete-time survival analysis to identify the impact of the intervention on dropout risk over time.

RESULTS

We find that IPT has a positive impact on dropout for government school students, but not for madrassa attendees. The difference was striking: in government schools, the odds of dropout in the treatment group were one third of those in the control group.

CONCLUSIONS

Our findings suggest that preventing early childhood malaria may reduce dropout at a relatively low cost. In this intervention, the drugs cost less than one dollar per year per child. While IPT is no longer practised in many countries due to concerns over drug resistance, these results support the conclusion that any type of effective malaria control programme protecting young children, such as consistent and correct use of bed nets, could improve educational attainment in areas where malaria is prevalent.

The significance of cerebral toxocariasis: a model system for exploring the link between brain involvement, behaviour and the immune response

Toxocara canis is a parasitic nematode that infects canines worldwide, and as a consequence of the widespread environmental dissemination of its ova in host faeces, other abnormal hosts including mice and humans are exposed to infection. In such abnormal or paratenic hosts, the immature third-stage larvae undergo a somatic migration through the organs of the body but fail to reach maturity as adult worms in the intestine. The presence of the migrating larvae contributes to pathology that is dependent upon the intensity of infection and the location of the larvae. A phenomenon of potential public health significance in humans and of ecological significance in mice is that T. canis larvae exhibit neurotrophic behaviour, which results in a greater concentration of parasites in the brain, as infection progresses. Toxocara larval burdens vary between individual outbred mice receiving the same inocula, suggesting a role for immunity in the establishment of cerebral infection. Although the systemic immune response to T. canis has been widely reported, the immune response in the brain has received little attention. Differential cytokine expression and other brain injury-associated biomarkers have been observed in infected versus uninfected outbred and inbred mice. Preliminary data have also suggested a possible link between significant memory impairment and cytokine production associated with T. canis infection. Mice provide a useful, replicable animal model with significant applicability and ease of manipulation. Understanding the cerebral host-parasite relationship may shed some light on the cryptic symptoms of human infection where patients often present with other CNS disorders such as epilepsy and mental retardation.

Population deworming every 6 months with albendazole in 1 million pre-school children in North India: DEVTA, a cluster-randomised trial

BACKGROUND

In north India many pre-school children are underweight, many have intestinal worms, and 2-3% die at ages 1·0-6·0 years. We used the state-wide Integrated Child Development Service (ICDS) infrastructure to help to assess any effects of regular deworming on mortality.

METHODS

Participants in this cluster-randomised study were children in catchment areas of 8338 ICDS-staffed village child-care centres (under-5 population 1 million) in 72 administrative blocks. Groups of four neighbouring blocks were cluster-randomly allocated in Oxford between 6-monthly vitamin A (retinol capsule of 200,000 IU retinyl acetate in oil, to be cut and dripped into the child's mouth every 6 months), albendazole (400 mg tablet every 6 months), both, or neither (open control). Analyses of albendazole effects are by block (36 vs 36 clusters). The study spanned 5 calendar years, with 11 6-monthly mass-treatment days for all children then aged 6-72 months. Annually, one centre per block was randomly selected and visited by a study team 1-5 months after any trial deworming to sample faeces (for presence of worm eggs, reliably assessed only after mid-study), weigh children, and interview caregivers. Separately, all 8338 centres were visited every 6 months to monitor pre-school deaths (100,000 visits, 25,000 deaths at age 1·0-6·0 years [the primary outcome]). This trial is registered at ClinicalTrials.gov, NCT00222547.

FINDINGS

Estimated compliance with 6-monthly albendazole was 86%. Among 2589 versus 2576 children surveyed during the second half of the study, nematode egg prevalence was 16% versus 36%, and most infection was light. After at least 2 years of treatment, weight at ages 3·0-6·0 years (standardised to age 4·0 years, 50% male) was 12·72 kg albendazole versus 12·68 kg control (difference 0·04 kg, 95% CI -0·14 to 0·21, p=0·66). Comparing the 36 albendazole-allocated versus 36 control blocks in analyses of the primary outcome, deaths per child-care centre at ages 1·0-6·0 years during the 5-year study were 3·00 (SE 0·07) albendazole versus 3·16 (SE 0·09) control, difference 0·16 (SE 0·11, mortality ratio 0·95, 95% CI 0·89 to 1·02, p=0·16), suggesting absolute risks of dying between ages 1·0 and 6·0 years of roughly 2·5% albendazole versus 2·6% control. No specific cause of death was significantly affected.

INTERPRETATION

Existing ICDS village staff can be organised to deliver simple pre-school interventions sustainably for many years at low cost, but regular deworming had little effect on mortality in this lightly infected pre-school population.

FUNDING

UK Medical Research Council, USAID, World Bank (albendazole donated by GlaxoSmithKline).

Deworming drugs for soil-transmitted intestinal worms in children: effects on nutritional indicators, haemoglobin and school performance

BACKGROUND

The World Health Organization (WHO) recommends treating all school children at regular intervals with deworming drugs in areas where helminth infection is common. The WHO state this will improve nutritional status, haemoglobin, and cognition and thus will improve health, intellect, and school attendance. Consequently, it is claimed that school performance will improve, child mortality will decline, and economic productivity will increase. Given the important health and societal benefits attributed to this intervention, we sought to determine whether they are based on reliable evidence.

OBJECTIVES

To summarize the effects of giving deworming drugs to children to treat soil-transmitted intestinal worms (nematode geohelminths) on weight, haemoglobin, and cognition; and the evidence of impact on physical well being, school attendance, school performance, and mortality.

SEARCH METHODS

In February 2012, we searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, EMBASE, LILACS, mRCT, and reference lists, and registers of ongoing and completed trials.

SELECTION CRITERIA

We selected randomized controlled trials (RCTs) and quasi-RCTs comparing deworming drugs for geohelminth worms with placebo or no treatment in children aged 16 years or less, reporting on weight, haemoglobin, and formal test of intellectual development. In cluster-RCTs treating communities or schools, we also sought data on school attendance, school performance, and mortality. We included trials that included health education with deworming.

DATA COLLECTION AND ANALYSIS

At least two authors independently assessed the trials, evaluated risk of bias, and extracted data. Continuous data were analysed using the mean difference (MD) with 95% confidence intervals (CI). Where data were missing, we contacted trial authors. We used GRADE to assess evidence quality, and this is reflected in the wording we used: high quality ("deworming improves...."); moderate quality ("deworming probably improves..."); low quality ("deworming may improve...."); and very low quality ("we don't know if deworming improves....").

MAIN RESULTS

We identified 42 trials, including eight cluster trials, that met the inclusion criteria. Excluding one trial where data are awaited, the 41 trials include 65,168 participants.Screening then treatingFor children known to be infected with worms (by screening), a single dose of deworming drugs may increase weight (0.58 kg, 95% CI 0.40 to 0.76, three trials, 139 participants; low quality evidence) and may increase haemoglobin (0.37 g/dL, 95% CI 0.1 to 0.64, two trials, 108 participants; low quality evidence), but we do not know if there is an effect on cognitive functioning (two trials, very low quality evidence).Single dose deworming for all childrenIn trials treating all children, a single dose of deworming drugs gave mixed effects on weight, with no effects evident in seven trials, but large effects in two (nine trials, 3058 participants, very low quality evidence). The two trials with a positive effect were from the same very high prevalence setting and may not be easily generalised elsewhere. Single dose deworming probably made little or no effect on haemoglobin (mean difference (MD) 0.06 g/dL, 95% CI -0.06 to 0.17, three trials, 1005 participants; moderate evidence), and may have little or no effect on cognition (two trials, low quality evidence).Mulitple dose deworming for all childrenOver the first year of follow up, multiple doses of deworming drugs given to all children may have little or no effect on weight (MD 0.06 kg, 95% CI -0.17 to 0.30; seven trials, 2460 participants; low quality evidence); haemoglobin, (mean 0.01 g/dL lower; 95% CI 0.14 lower to 0.13 higher; four trials, 807 participants; low quality evidence); cognition (three trials, 30,571 participants, low quality evidence); or school attendance (4% higher attendance; 95% CI -6 to 14; two trials, 30,243 participants; low quality evidence);For time periods beyond a year, there were five trials with weight measures. One cluster-RCT of 3712 children in a low prevalence area showed a large effect (average gain of 0.98 kg), whilst the other four trials did not show an effect, including a cluster-RCT of 27,995 children in a moderate prevalence area (five trials, 37,306 participants; low quality evidence). For height, we are uncertain whether there is an effect of deworming (-0.26 cm; 95% CI -0.84 to 0.31, three trials, 6652 participants; very low quality evidence). Deworming may have little or no effect on haemoglobin (0.00 g/dL, 95%CI -0.08 to 0.08, two trials, 1365 participants, low quality evidence); cognition (two trials, 3720 participants; moderate quality evidence). For school attendance, we are uncertain if there is an effect (mean attendance 5% higher, 95% CI -0.5 to 10.5, approximately 20,000 participants, very low quality evidence).Stratified analysis to seek subgroup effects into low, medium and high helminth endemicity areas did not demonstrate any pattern of effect. In a sensitivity analysis that only included trials with adequate allocation concealment, we detected no significant effects for any primary outcomes.One million children were randomized in a deworming trial from India with mortality as the primary outcome. This was completed in 2005 but the authors have not published the results.

AUTHORS' CONCLUSIONS

Screening children for intestinal helminths and then treating infected children appears promising, but the evidence base is small. Routine deworming drugs given to school children has been more extensively investigated, and has not shown benefit on weight in most studies, except for substantial weight changes in three trials conducted 15 years ago or more. Two of these trials were carried out in the same high prevalence setting. For haemoglobin and cognition, community deworming seems to have little or no effect, and the evidence in relation to school attendance, and school performance is generally poor, with no obvious or consistent effect. Our interpretation of this data is that it is probably misleading to justify contemporary deworming programmes based on evidence of consistent benefit on nutrition, haemoglobin, school attendance or school performance as there is simply insufficient reliable information to know whether this is so.

Deworming drugs for soil-transmitted intestinal worms in children: effects on nutritional indicators, haemoglobin and school performance

BACKGROUND

The World Health Organization (WHO) recommends treating all school children at regular intervals with deworming drugs in areas where helminth infection is common. The WHO state this will improve nutritional status, haemoglobin, and cognition and thus will improve health, intellect, and school attendance. Consequently, it is claimed that school performance will improve, child mortality will decline, and economic productivity will increase. Given the important health and societal benefits attributed to this intervention, we sought to determine whether they are based on reliable evidence.

OBJECTIVES

To summarize the effects of giving deworming drugs to children to treat soil-transmitted intestinal worms (nematode geohelminths) on weight, haemoglobin, and cognition; and the evidence of impact on physical well being, school attendance, school performance, and mortality.

SEARCH METHODS

In February 2012, we searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, EMBASE, LILACS, mRCT, and reference lists, and registers of ongoing and completed trials.

SELECTION CRITERIA

We selected randomized controlled trials (RCTs) and quasi-RCTs comparing deworming drugs for geohelminth worms with placebo or no treatment in children aged 16 years or less, reporting on weight, haemoglobin, and formal test of intellectual development. In cluster-RCTs treating communities or schools, we also sought data on school attendance, school performance, and mortality. We included trials that included health education with deworming.

DATA COLLECTION AND ANALYSIS

At least two authors independently assessed the trials, evaluated risk of bias, and extracted data. Continuous data were analysed using the mean difference (MD) with 95% confidence intervals (CI). Where data were missing, we contacted trial authors. We used GRADE to assess evidence quality, and this is reflected in the wording we used: high quality ("deworming improves...."); moderate quality ("deworming probably improves..."); low quality ("deworming may improve...."); and very low quality ("we don't know if deworming improves....").

MAIN RESULTS

We identified 42 trials, including eight cluster trials, that met the inclusion criteria. Excluding one trial where data are awaited, the 41 trials include 65,168 participants.For programmes that treat only children detected as infected (by screening), a single dose of deworming drugs probably increased weight (0.58 kg, 95% CI 0.40 to 0.76, three trials, 139 participants; moderate quality evidence) and may have increased haemoglobin (0.37 g/dL, 95% CI 0.1 to 0.64, two trials, 108 participants; low quality evidence), but we do not know if there is an effect on cognitive functioning (two trials, very low quality evidence).For a single dose of deworming drugs given to all children in endemic areas, there were mixed effects on weight, with no effects evident in seven trials, but large effects in two. Overall our analysis indicated that we are uncertain whether there was an effect on weight (nine trials, 3058 participants; very low quality evidence). For haemoglobin, deworming made little or no difference (0.02 g/dL, 95% CI -0.05 to 0.09, four trials, 1992 participants; low quality evidence), and we don't know if it improves cognition (one trial, very low quality evidence).For multiple doses of deworming drugs with follow up for up to one year given to all children in endemic areas, we are uncertain if there is an effect on weight (0.06 kg, 95% CI -0.17 to 0.30; seven trials, 2460 participants; very low quality evidence); cognition (three trials, very low quality evidence); or school attendance (4% higher attendance; 95% CI -6 to 14; two trials, 75 clusters and 143 individually randomized participants, very low quality evidence). For haemoglobin, the intervention may have little or no effect (mean 0.01 g/dL lower; 95% CI 0.14 lower to 0.13 higher; four trials, 807 participants; low quality evidence).For multiple doses of deworming drugs with follow up beyond one year given to all children in endemic areas there were five trials with weight measures. One cluster-RCT of 3712 children in a low prevalence area showed a large effect (average gain of 0.98kg), whilst the other four trials did not show an effect, including a cluster-RCT of 27,995 children in a moderate prevalence area. Overall, we are uncertain if there is an effect for weight (five trials, 302 clusters and 1045 individually randomized participants; very low quality evidence). For other outcomes, we are uncertain whether deworming affects height (-0.26 cm; 95%CI -0.84 to 0.31, three trials, 1219 participants); haemoglobin (0.02 g/dL, 95%CI 0.3 to 0.27, two trials, 1365 participants); cognition (two trials), or school attendance (mean attendance 5% higher, 95% CI -0.5 to 10.5, one trial, 50 clusters).Stratified analysis to seek subgroup effects into low, medium and high helminth endemicity areas did not demonstrate any pattern of effect. We did not detect any significant effects for any primary outcomes in a sensitivity analysis only including trials with adequate allocation concealment.One million children were randomized in a deworming trial from India with mortality as the primary outcome. This was completed in 2005 but the authors have not published the results.

AUTHORS' CONCLUSIONS

Screening children for intestinal helminths and then treating infected children appears promising, but the evidence base is small. Routine deworming drugs given to school children has been more extensively investigated, and has not shown benefit on weight in most studies, except for substantial weight changes in three trials conducted 15 years ago or more. Two of these trials were carried out in the same high prevalence setting. For haemoglobin, community deworming seems to have little or no effect, and the evidence in relation to cognition, school attendance, and school performance is generally poor, with no obvious or consistent effect. Our interpretation of this data is that it is probably misleading to justify contemporary deworming programmes based on evidence of consistent benefit on nutrition, haemoglobin, school attendance or school performance as there is simply insufficient reliable information to know whether this is so.

Epidemiology of hookworm infection in Kintampo North Municipality, Ghana: patterns of malaria coinfection, anemia, and albendazole treatment failure

A cross-sectional pilot study of hookworm infection was carried out among 292 subjects from 62 households in Kintampo North, Ghana. The overall prevalence of hookworm infection was 45%, peaking in those 11-20 years old (58.5%). In children, risk factors for hookworm infection included coinfection with malaria and increased serum immunoglobulin G reactivity to hookworm secretory antigens. Risk factors for infection in adults included poor nutritional status, not using a latrine, not wearing shoes, and occupation (farming). Although albendazole therapy was associated with an overall egg reduction rate of 82%, 37 subjects (39%) remained infected. Among those who failed therapy, treatment was not associated with a significant reduction in egg excretion, and nearly one-third had higher counts on repeat examination. These data confirm a high prevalence of low-intensity hookworm infection in central Ghana and its association with poor nutritional status. The high rate of albendazole failure raises concern about emerging resistance.

Turning neglected tropical diseases into forgotten maladies

Because they afflict mostly poor people in poor countries, killing relatively few compared to the many who suffer from severe chronic disabilities, a large cluster of infections deserve the label of neglected tropical diseases (NTDs). That is changing as these diseases' enormous health, educational, and economic toll is better understood, including how they interact with HIV/AIDS, malaria, and other illnesses. Several NTDs could be controlled or even eliminated within a decade, using integrated, highly cost-effective mass drug administration programs together with nondrug interventions. Research is needed to provide additional means of control for these conditions and make elimination feasible for still others.

Ascaris and ascariasis

Ascaris lumbricoides and Ascaris suum are widespread parasitic nematodes of humans and pigs respectively. Recent prevalence data suggests that approximately 1.2 billion people are infected. Adult worms exhibit an overdispersed frequency distribution in their hosts and individuals harbouring heavy burdens display associated morbidity. In this review, we describe the parasite, its distribution and measures undertaken to control infection.

Health, Human Capital, and Development

How much does disease depress development in human capital and income around the world? I discuss a range of micro evidence, which finds that health is both human capital itself and an input to producing other forms of human capital. I use a standard model to integrate these results, and suggest a re-interpretation of much of the micro literature. I then discuss the aggregate implications of micro estimates, but note the complications in extrapolating to general equilibrium, especially because of health's effect on population size. I also review the macro evidence on this topic, which consists of either cross-country comparisons or measuring responses to health shocks. Micro estimates are 1-2 orders of magnitude smaller than the cross-country relationship, but nevertheless imply high benefit-to-cost ratios from improving certain forms of health.

Impact of hookworm infection and deworming on anaemia in non-pregnant populations: a systematic review

Objectives

To summarise age- and intensity-stratified associations between human hookworm infection and anaemia and to quantify the impact of treatment with the benzimidazoles, albendazole and mebendazole, on haemoglobin and anaemia in non-pregnant populations.

Methods

Electronic databases (MEDLINE, EMBASE, PubMed) were searched for relevant studies published between 1980 and 2009, regardless of language, and researchers contacted about potential data. Haemoglobin concentration (Hb) was compared between uninfected individuals and individuals harbouring hookworm infections of different intensities, expressed as standardised mean differences (SMD) and 95% confidence intervals (CI). Meta-analysis of randomised control trials (RCTs) investigated the impact of treatment on Hb and anaemia.

Results

Twenty-three cross-sectional studies, six pre- and post-intervention studies and 14 trials were included. Among cross-sectional studies, moderate- and heavy-intensity hookworm infections were associated with lower Hb in school-aged children, while all levels of infection intensity were associated with lower Hb in adults. Among RCTs using albendazole, impact of treatment corresponded to a 1.89 g/l increase (95%CI: 0.13–3.63) in mean Hb while mebendazole had no impact. There was a positive impact of 2.37 g/l (95%CI: 1.33–3.50) on mean Hb when albendazole was co-administered with praziquantel, but no apparent additional benefit of treatment with benzimidazoles combined with iron supplementation. The mean impact of treatment with benzimidazoles alone on moderate anaemia was small (relative risk (RR) 0.87) with a larger effect when combined with praziquantel (RR 0.61).

Conclusions

Anaemia is most strongly associated with moderate and heavy hookworm infection. The impact of anthelmintic treatment is greatest when albendazole is co-administered with praziquantel.

Which new approaches to tackling neglected tropical diseases show promise?

This PLoS Medicine Debate examines the different approaches that can be taken to tackle neglected tropical diseases (NTDs). Some commentators, like Jerry Spiegel and colleagues from the University of British Columbia, feel there has been too much focus on the biomedical mechanisms and drug development for NTDs, at the expense of attention to the social determinants of disease. Burton Singer argues that this represents another example of the inappropriate "overmedicalization" of contemporary tropical disease control. Peter Hotez and colleagues, in contrast, argue that the best return on investment will continue to be mass drug administration for NTDs.

Socioeconomic aspects of neglected tropical diseases

Although many examples of highly cost-effective interventions to control neglected tropical diseases exist, our understanding of the full economic effect that these diseases have on individuals, households, and nations needs to be improved to target interventions more effectively and equitably. We review data for the effect of neglected tropical diseases on a population's health and economy. We also present evidence on the costs, cost-effectiveness, and financing of strategies to monitor, control, or reduce morbidity and mortality associated with these diseases. We explore the potential for economies of scale and scope in terms of the costs and benefits of successfully delivering large-scale and integrated interventions. The low cost of neglected tropical disease control is driven by four factors: the commitment of pharmaceutical companies to provide free drugs; the scale of programmes; the opportunities for synergising delivery modes; and the often non-remunerated volunteer contribution of communities and teachers in drug distribution. Finally, we make suggestions for future economic research.

Deworming helminth co-infected individuals for delaying HIV disease progression

BACKGROUND

The HIV-1 pandemic has disproportionately affected individuals in resource-constrained settings where other infectious diseases, such as helminth infections, also are highly prevalent. There are biologically plausible reasons for possible effects of helminth infection in HIV-1-infected individuals, and findings from multiple studies suggest that helminth infection may adversely affect HIV-1 progression. Since initial publication of this review (Walson 2007), additional data from randomized controlled trials (RCTs) has become available. We sought to evaluate all currently available evidence to determine if treatment of helminth infection in HIV-1 co-infected individuals impacts HIV-1 progression.

OBJECTIVES

To determine if treating helminth infection in individuals with HIV-1 can reduce the progression of HIV-1 as determined by changes in CD4 count, viral load, or clinical disease progression.

SEARCH STRATEGY

In this 2008 update, we searched online for published and unpublished studies in The Cochrane Library, MEDLINE, EMBASE, CENTRAL, and AIDSEARCH. We also searched databases listing conference abstracts, scanned reference lists of articles, and contacted authors of included studies.

SELECTION CRITERIA

We searched for RCTs and quasi-RCTs that compared HIV-1 progression as measured by changes in CD4 count, viral load, or clinical disease progression in HIV-1 infected individuals receiving anti-helminthic therapy.

DATA COLLECTION AND ANALYSIS

Data regarding changes in CD4 count, HIV-1 RNA levels, and/or clinical staging after treatment of helminth co-infection were extracted from identified studies.

MAIN RESULTS

Of 7,019 abstracts identified (6,384 from original searches plus 635 from updated searches), 17 abstracts were identified as meeting criteria for potential inclusion (15 from previous review plus an additional two RCTs). After restricting inclusion to RCTs, a total of three studies were eligible for inclusion in this updated review.All three trials showed individual beneficial effects of helminth eradication on markers of HIV-1 disease progression (HIV-1 RNA and/or CD4 counts). When data from these trials were pooled, the analysis demonstrated significant benefit of deworming on both plasma HIV-1 RNA and CD4 counts.

AUTHORS' CONCLUSIONS

To date, three RCTs have evaluated the effects of deworming on markers of HIV-1 disease progression in helminth and HIV-1 co-infected individuals. All trials demonstrate benefit in attenuating or reducing plasma viral load and/or increasing CD4 counts. When taken together, there is evidence of benefit for deworming HIV-1 co-infected adults. Given that these studies evaluated different helminth species and different interventions, further trials are warranted to evaluate species-specific effects and to document long-term clinical outcomes following deworming.