Maternal Deworming Research Study (MADRES) protocol: a double-blind, placebo-controlled randomised trial to determine the effectiveness of deworming in the immediate postpartum period

Parasites and childhood stunting - a mechanistic interplay with nutrition, anaemia, gut health, microbiota, and epigenetics

Globally, stunting affects approximately 149.2 million children under 5 years of age. The underlying aetiology and pathophysiological mechanisms leading to stunting remain elusive, and therefore few effective treatment and prevention strategies exist. Crucial evidence directly linking parasites to stunting is often lacking - in part due to the complex nature of stunting, as well as a lack of critical multidisciplinary research amongst key age groups. Here, based on available studies, we present potential mechanistic pathways by which parasitic infection of mother and/or infant may lead to childhood stunting. We highlight the need for future multidisciplinary longitudinal studies and clinical trials aimed at elucidating the most influential factors, and synergies therein, that can lead to stunting, and ultimately towards finding solutions to successfully mitigate against it.

Effect of mass deworming with antihelminthics for soil-transmitted helminths during pregnancy

BACKGROUND

Helminthiasis is an infestation of the human body with parasitic worms. It is estimated to affect 44 million pregnancies, globally, each year. Intestinal helminthiasis (hookworm infestation) is associated with blood loss and decreased supply of nutrients for erythropoiesis, resulting in iron-deficiency anaemia. Over 50% of the pregnant women in low- and middle-income countries (LMIC) suffer from iron-deficiency anaemia. Though iron-deficiency anaemia is multifactorial, hookworm infestation is a major contributory cause in women of reproductive age in endemic areas. Antihelminthics are highly efficacious, but evidence of their beneficial effect and safety when given during pregnancy has not been established. This is an update of a Cochrane Review last published in 2015.

OBJECTIVES

To determine the effects of mass deworming with antihelminthics for soil-transmitted helminths (STH) during the second or third trimester of pregnancy on maternal and pregnancy outcomes.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP) (8 March 2021) and reference lists of retrieved studies.

SELECTION CRITERIA

We included all prospective randomised controlled trials evaluating the effect of administration of antihelminthics versus placebo or no treatment during the second or third trimester of pregnancy; both individual-randomised and cluster-randomised trials were eligible. We excluded quasi-randomised trials and studies that were only available as abstracts with insufficient information.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data, checked accuracy and assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included a total of six trials (24 reports) that randomised 7873 pregnant women. All of the included trials were conducted in antenatal clinics within hospitals in LMICs (Uganda, Nigeria, Peru, India, Sierra Leone and Tanzania). Among primary outcomes, five trials reported maternal anaemia, one trial reported preterm birth and three trials reported perinatal mortality. Among secondary outcomes, included trials reported maternal worm prevalence, low birthweight (LBW) and birthweight. None of the included studies reported maternal anthropometric measures or infant survival at six months. Overall, we judged the included trials to be generally at low risk of bias for most domains, while the certainty of evidence ranged from low to moderate. Analysis suggests that administration of a single dose of antihelminthics in the second trimester of pregnancy may reduce maternal anaemia by 15% (average risk ratio (RR) 0.85, 95% confidence interval (CI) 0.72 to 1.00; I²= 86%; 5 trials, 5745 participants; low-certainty evidence). We are uncertain of the effect of antihelminthics during pregnancy on preterm birth (RR 0.84, 95% CI 0.38 to 1.86; 1 trial, 1042 participants; low-certainty evidence) or perinatal mortality (RR 1.01, 95% CI 0.67 to 1.52; 3 trials, 3356 participants; low-certainty evidence). We are uncertain of the effect of antihelminthics during pregnancy on hookworm (average RR 0.31, 95% CI 0.05 to 1.93; Tau² = 1.76, I² = 99%; 2 trials, 2488 participants; low-certainty evidence). Among other secondary outcomes, findings suggest that administration of antihelminthics during pregnancy may reduce the prevalence of trichuris (average RR 0.68, 95% CI 0.48 to 0.98; I²=75%; 2 trials, 2488 participants; low-certainty evidence) and ascaris (RR 0.24, 95% CI 0.19 to 0.29; I²= 0%; 2 trials, 2488 participants; moderate-certainty evidence). Antihelminthics during pregnancy probably make little or no difference to LBW (RR 0.89, 95% CI 0.69 to 1.16; 3 trials, 2960 participants; moderate-certainty evidence) and birthweight (mean difference 0.00 kg, 95% CI -0.03 kg to 0.04 kg; 3 trials, 2960 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

The evidence suggests that administration of a single dose of antihelminthics in the second trimester of pregnancy may reduce maternal anaemia and worm prevalence when used in settings with high prevalence of maternal helminthiasis. Further data is needed to establish the benefit of antihelminthic treatment on other maternal and pregnancy outcomes. Future research should focus on evaluating the effect of these antihelminthics among various subgroups in order to assess whether the effect varies. Future studies could also assess the effectiveness of co-interventions and health education along with antihelminthics for maternal and pregnancy outcomes.

Maternal postpartum deworming and infant milk intake: Secondary outcomes from a trial

The World Health Organization recommends deworming to reduce soil-transmitted helminth (STH)-attributable morbidity in women of reproductive age, including pregnant and lactating women, to reduce blood loss, iron deficiency anaemia and nutrient malabsorption. This study assessed the impact of maternal postpartum deworming with albendazole approximately 1 day after delivery on infant milk intake among a subset of 216 randomly selected mother-infant pairs recruited into a large trial in Peru. Infant milk intake was measured using the deuterium-oxide method at 1- and 6-month postpartum. Maternal STH infection was measured at 6-month postpartum. At 1-month postpartum, mean intake was 756 ± 16 and 774 ± 18 mL day^-1 in the albendazole and placebo groups, respectively (mean difference: -18 mL day^-1 ; 95% CI: -65, 30). At 6-month postpartum, mean intake was 903 ± 16 and 908 ± 18 mL day^-1 in the albendazole and placebo groups, respectively (mean difference: -5 mL day^-1 ; 95% CI: -52, 43). There was no statistically significant difference in milk intake between groups at either time point. At 6-month postpartum, mothers infected with Trichuris trichiura had infants with higher milk intakes (adjusted mean difference: 70 mL day^-1 ; 95% CI: 20, 120) compared with uninfected mothers. However, there was no statistically significant difference in infant milk intake between mothers who had moderate-and-heavy intensity infection compared with the comparison group (mothers with no and light intensity infection). A lower prevalence and intensity of infection, and inclusion of uninfected mothers in both arms of the trial, resulting in effect dilution, may explain the null findings.

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.

A Double-Blind Randomized Controlled Trial of Maternal Postpartum Deworming to Improve Infant Weight Gain in the Peruvian Amazon

Background

Nutritional interventions targeting the critical growth and development period before two years of age can have the greatest impact on health trajectories over the life course. Compelling evidence has demonstrated that interventions investing in maternal health in the first 1000 days of life are beneficial for both mothers and their children. One such potential intervention is deworming integrated into maternal postpartum care in areas where soil-transmitted helminth (STH) infections are endemic.

Methodology/Principal Findings

From February to August 2014, 1010 mother-infant pairs were recruited into a trial aimed at assessing the effectiveness of maternal postpartum deworming on infant and maternal health outcomes. Following delivery, mothers were randomly assigned to receive either single-dose 400 mg albendazole or placebo. Participants were followed-up at 1 and 6 months postpartum. There was no statistically significant difference in mean weight gain between infants in the experimental and control groups (mean difference: -0.02; 95% CI: -0.1, 0.08) at 6 months of age. Further, deworming had no effect on measured infant morbidity indicators. However, ad hoc analyses restricted to mothers who tested positive for STHs at baseline suggest that infants of mothers in the experimental group had greater mean length gain in cm (mean difference: 0.8; 95% CI: 0.1, 1.4) and length-for-age z-score (mean difference: 0.5; 95% CI: 0.2, 0.8) at 6 months of age.

Conclusions/Significance

In a study population composed of both STH-infected and uninfected mothers, maternal postpartum deworming was insufficient to impact infant growth and morbidity indicators up to 6 months postpartum. Among STH-infected mothers, however, important improvements in infant length gain and length-for-age were observed. The benefits of maternal postpartum deworming should be further investigated in study populations having higher overall prevalences and intensities of STH infections and, in particular, where whipworm and hookworm infections are of public health concern.

Trial registration

ClinicalTrials.gov (NCT01748929).

Worldwide, over one billion people are infected with intestinal worms (roundworms, whipworms, and hookworms). In worm-endemic areas, women of reproductive age are a high risk group for infection because of their poor nutritional status and increased physiological needs during pre-pregnancy, pregnancy, and lactation. To measure the effect of providing mothers with deworming treatment soon after delivery, we conducted a trial in 1010 mother-infant pairs. Mothers were randomly assigned to receive either a single-dose deworming tablet or a placebo tablet. Mothers and their infants were visited in their homes at 1 and 6 months following delivery. At the 6-month time point, among all mother-infant pairs, we could not detect an effect of deworming on infant growth or morbidity. We did, however, observe that, among women who were infected with intestinal worms at baseline, deworming had a beneficial effect on important infant growth outcomes. The potential benefit of maternal postpartum deworming in populations with higher prevalences and intensities of intestinal worms, particularly where infections with whipworm and hookworm predominate, warrants further investigation.

Governance, organization, accountability and sustainability of a region-wide school-based deworming program in Loreto, Peru

Chau Cuica was the name given by the regional government of Loreto in Peru for its school-based deworming program which was initiated in 2012 with a donation of mebendazole from an international non-governmental organization. Embedded in the program from the start was a sentinel surveillance component which consisted of 16 sentinel schools representing Loreto's seven provinces. Coverage rates varied between 35% and 61% over the first two years of the program (and seven deworming cycles). Initial prevalences of soil-transmitted helminth infections were high, with 82.4% of schoolchildren having at least one infection and prevalences of both Ascaris lumbricoides and Trichuris trichiura infections both exceeding 60%. After two years, these prevalences had dropped to 56% for any STH infection, 38% for A. lumbricoides and 34% for T. trichiura. Importantly, the proportions of children with moderate and heavy infections also dropped. Both the regional Ministry of Health and the Ministry of Education were jointly charged to implement this deworming program. The program's costs were estimated to be approximately 22 cents (USD) per child per deworming cycle. The responsibility for the surveillance component was initially undertaken by research partners from a local NGO and a Canadian university, which transferred gradually over the course of the deworming program to being entirely the responsibility of the Ministry of Health. This regional deworming program may serve as a model for other jurisdictions that are planning a school-based deworming program with an integrated surveillance component to monitor impact.