Independent and combined effects of improved WASH and improved complementary feeding on child stunting and anaemia in rural Zimbabwe

Summary of research¹

Child stunting reduces survival and impairs neurodevelopment. Offspring of adults who were stunted as children are at increased risk of stunting. Targeted interventions have largely failed to address stunting. Childhood anaemia is also prevalent among children under two years old in Africa and Asia and is a primary cause of cognitive delay. Increasing dietary iron intake only reduces anaemia by 32-62% (SHINE, 2015). The UNICEF framework for undernutrition highlights inadequate dietary intake and disease as the immediate causes of child undernutrition and specifies that a multi-sector approach that addresses both proximal and distal determinants is required. Thus, integration of improved infant diets with improved water, sanitation and hygiene (WASH) is a logical approach, given the role of WASH in reducing morbidity, especially diarrhoea. In this study the independent and combined effects of improved WASH and improved infant and young child feeding (IYCF) on stunting and anaemia were tested in rural Zimbabwe (SHINE trial).

A cluster-randomised, community-based, 2 × 2 factorial trial was carried out in two rural districts in Zimbabwe. Clusters were defined as the catchment area of between one and four village health workers employed by the Zimbabwe Ministry of Health and Child Care. Women were eligible for inclusion if they permanently lived in clusters and were confirmed pregnant. Clusters were randomly assigned (1:1:1:1) to standard of care (52 clusters), IYCF (20 g of a small-quantity lipid-based nutrient supplement (LNS) per day from age 6 to 18 months plus complementary feeding counselling; 53 clusters), WASH (construction of a ventilated improved pit latrine, provision of two handwashing stations, liquid soap, chlorine, and play space plus hygiene counselling; 53 clusters), or IYCF plus WASH (53 clusters). A constrained randomisation technique was used to achieve balance across the groups for 14 variables related to geography, demography, water access and community-level sanitation coverage. Masking of participants and fieldworkers was not possible. The primary outcomes were infant length-for-age z-score (LAZ) and haemoglobin concentrations at 18 months of age among children born to mothers who were HIV negative during pregnancy. These outcomes were analysed in the intention-to-treat population. The authors estimated the effects of the interventions by comparing the two IYCF groups with the two non-IYCF groups and the two WASH groups with the two non-WASH groups, except for outcomes that had an important statistical interaction between the interventions.

Between 22 November 2012 and 27 March 2015, 5,280 pregnant women were enrolled from 211 clusters. A total of 3,686 children born to HIV-negative mothers were assessed at age 18 months (884 in the standard of care group from 52 clusters, 893 in the IYCF group from 53 clusters, 918 in the WASH group from 53 clusters, and 991 in the IYCF plus WASH group from 51 clusters). In the IYCF intervention groups, the mean LAZ was 0·16 (95% CI 0·08–0·23) higher and the mean haemoglobin concentration was 2·03 g/L (1·28–2·79) higher than those in the non-IYCF intervention groups. The IYCF intervention reduced the number of stunted children from 620 (35%) of 1,792 to 514 (27%) of 1,879 and the number of children with anaemia from 245 (13·9%) of 1,759 to 193 (10·5%) of 1,845 and significantly increased mean weight-for-age, weight-for-height and head-circumference-for-age Z scores compared with the non-IYCF interventions. The WASH intervention had no effect on either primary outcome. Neither the IYCF nor the WASH intervention reduced the prevalence of diarrhoea at 12 or 18 months of age. 

The authors discuss the fact that, consistent with decades of complementary feeding research, the IYCF interventions increased linear growth and haemoglobin concentrations, reduced stunting by 21%, reduced anaemia by 24% and increased head circumference and ponderal growth compared with the non-IYCF interventions. Although the effects of complementary feeding education could not be separated out from those of LNS, formative work shows that both components are important. In contrast, no benefit was detected for the WASH intervention on any reported child health outcomes. This finding is inconsistent with a previous review on water chlorination and handwashing promotion, which were estimated to reduce diarrhoea by around 25% (Ejemot-Nwadiaro et al, 2015); most studies in this review had very high intervention doses (daily to weekly contact between behaviour-change promoters and study participants), which was greater than the monthly contact delivered by SHINE. Thus, adherence may not be sufficient to reduce diarrhoea when intervention dose is less frequent than monthly, even when behaviour-change messages are based on extensive formative research, delivered by highly trained workers and accompanied by free provision of soap and chlorine, as in SHINE. 

Another important aspect may be that SHINE intervened at the household rather than community level as it was reasoned that young children spend most of their time within their own household. Increased community sanitation coverage, even in sparsely populated areas, may be required to affect growth. Also, although the SHINE WASH intervention considerably reduced geophagia and consumption of chicken faeces by maternal history, it did not prevent these behaviours (27% of WASH mothers still reported they had observed geophagia at the 12-month visit); more analysis of the data is needed to find out why.

SHINE is the third trial in which a WASH intervention alone or in combination with an IYCF intervention had no effect on linear growth (Luby et al, 2018; Null et al, 2018). Although these findings do not unequivocally prove that an integrated WASH-nutrition approach will never improve linear growth in any context, these trials included over 18,000 children in three diverse settings with prevalent stunting and poor environmental hygiene and infant diets. The authors propose that this may be because faecal ingestion does not reduce environmental enteric dysfunction (EED) (or prevention of EED does not improve linear growth); that WASH interventions used were not sufficiently effective to facilitate linear growth or reduce diarrhoea; or that the trials did not address intergenerational prenatal factors that could potentially be targeted by preconception dietary supplementation of mothers.

There is a large movement to scale up integrated WASH-nutrition interventions for stunting prevention. The SHINE trial provides high-level evidence that elementary WASH interventions delivered at the household level in rural areas of low-income and middle-income countries are unlikely to reduce stunting and might not reduce diarrhoea, and that implementation of these WASH interventions together with IYCF interventions will not reduce stunting more than implementation of IYCF alone. These findings provide an urgent call for greater investment in the WASH sector to identify and deliver more efficacious interventions.

Endnote

¹Humphrey, Mbuya, Ntozini, Moulton, et al. (2019). Independent and combined effects of improved water, sanitation, and hygiene, and improved complementary feeding, on child stunting and anaemia in rural Zimbabwe: a cluster-randomised trial. Lancet Glob Health. 2019 Jan;7(1):e132-e147. doi: 10.1016/S2214-109X(18)30374-7. www.thelancet.com/journals/langlo/article/PIIS2214-109X(18)30374-7/fulltext

References

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Luby SP, Rahman M, Arnold BF, et al. Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Bangladesh: a cluster randomised controlled trial. Lancet Glob Health 2018; 6: e302–15.

Null C, Stewart CP, Pickering AJ, et al. Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Kenya: a cluster-randomised controlled trial. Lancet Glob Health 2018; 6: e316–29.

SHINE Trial team. The Sanitation Hygiene Infant Nutrition Efficacy (SHINE) trial: rationale, design, and methods. Clin Infect Dis 2015; 61 (suppl 7): S685–702.