from EVIDENCE to POLICY THWBN S~BR IDmSS*A Learning what works for better programs and policies June 2015 KENYA: Do Infants Benefit When Older Siblings are Dewormed? Early childhood is a crucial window of opportunity for im- provide the evidence of impact. In Kenya, a World Bank re- proving lives. It's a time when children's brains and bod- searcher went back after a decade to measure the impact of a ies rely on good nutrition, health care and stimulation for deworming campaign on young children whose older siblings proper development. and neighbors had received the deworming medication. The The impacts, as a recent younger children hadn't received the parasite-killing drugs evaluation of an early themselves. These younger siblings, now around 11 and childhood stimulation 12 years old, did better on cognitive tests than young chil- program in Jamaica dren whose older siblings hadt received the medication showed (see Evidence at that time. The evaluation indicates that having fewer to Policy: Can Dis- worms in their communities gave these younger children advantaged Kids Ever a boost, most likely because they faced lower risk of infec- Catch Up with Better- tion during a vital period of development. The results are off Peers?), can be life- a reminder of the importance of following up on devel- long. The challenge for policymakers and development opment programs to measure long-term impacts that can experts is knowing which programs give children's develop- show lasting improvements in the lives of millions. Cur- ment the best boost and how to implement them. rently, deworming in Kenya has been scaled up nation- The World Bank is committed to helping governments wide, giving primary school age children better health understand whether programs to improve lives are succeed- and, as this evaluation shows, the chance for cognitive ing. Rigorous impact evaluations are often carried out to improvement for the youngest family members too. Intestinal worms are among the most common infections with at least one parasite, and most infections werent treat- in the world. More than one billion people are infected, ed despite the availability of medicines. Between 1998 and mainly children in Asia and Sub-Saharan Africa. The 2001, a deworming program was randomly phased in among worms live in the human gut and absorb key nutrients, 75 primary schools in western Kenya. An impact evaluation like iron, that would otherwise nourish their human host, found that moderate-to-heavy infections were reduced and While infection is rarely fatal, worms can cause diarrhea, school attendance went up among children who received the abdominal pain, anemia, general malaise, and weakness. deworming treatment. Importantly, the relatively low-cost Two decades ago, researchers Edward Miguel of the Uni- program also raised school attendance for children who didnt versity of California, Berkeley, and Michael Kremer of Har- get the drugs and lived in the same community indicating yard University, sought to reduce worm infections among that these children were less likely to get infected and suffer children in western Kenya. The problem was particularly the effects that could keep them from schoo l A recent repli- acute there-more than 92 percent of children were infected cation study upheld these main results of this paper. * "Worms: Identifying impacts on education and health in the presence of treatment externalities", Econometrica, Vol. 72, No. 1 (January, 2004), 159-217, Edwad Mgue an Mihae Krmer,htt://egabererently,sstsdewormingc-prjein/llKenyaig-hascs-beencato scaledalt- upth nation--of Edwar igrulan ipatelutosaeoencriduto imrveetfoheyugetfaiymebrsto Treatment-Externalities.pdfC ** I Re-analysis of health and educational impacts of a school-based deworming programme in western Kenya: a pure replication," It. J. Epidemiology. First published onine July 22, 2015, Alexander M Aiken, Calu Davey, James R Hargreaves, and Richard J Hayes, http:Thije.oxfordjournals.orgcontent/early2015/07/21ije. dyv e 27.abstract Longer term follow-up surveys on children eligible for Recently, a World Bank research team decided to deworming didn't find evidence of improvements in general take a long-term look at children in the same commu- intelligence as a result of the intervention, but did detect in- nities who didn't receive the treatment because they creased time spent in school and work, and higher earnings were infants or toddlers at the time. Given the well- among wage workers. Since the window considered most known spillover effects on primary school aged chil- important for child cognitive development had already dren who didn't get treated, the question was whether passed at the time of the intervention, the lack of impact on there was any similar impact on very young children intelligence isn't surprising. The labor market improvements and whether improved health then might have boosted are attributed to the childhood health improvements chang- their achievement later on. ing both child and later adult time allocations.* Evaluationi The impact evaluation, carried out in 2009-20 10, focused project schools in Samia and Bunyala districts of Ke- on children who were infants when the deworming start- nya's Western Province. Cognitive tests were conducted ed. These children didn't get the deworming treatment among a subset of slightly more than 2,400 children. themselves during the original deworming study, because The researchers wanted to know if better health in early the treatment was aimed at primary school children. childhood produced a long-term impact on cognition, The original deworming project's randomized design- given that these children's older siblings and neighbors treatment was phased in across entire communities over a had received deworming drugs. period of a few years-allowed researchers to avoid prob- The children were tested for "verbal fluency," in lems that hampered earlier studies, which lacked true con- which children name as many items in a category-in trol groups. In the communities where deworming began this case food and animals-as they can in a minute. in 1998, children born that same year were identified as the Researchers also used the Peabody Picture Vocabulary treatment group because the deworming program started Test to measure "receptive vocabulary," in which chil- when they were under the age of one. In the communities dren point to one of four pictures that best matches a where the phased-in deworming didn't start until 2001, word read aloud to them. To test reasoning, research- children born in 1998 were three years old before they could ers relied on a set of questions from Raven's Progressive potentially experience any of the effects from siblings' be- Matrices, a series of puzzles that measure nonverbal ing dewormed. For the purpose of this evaluation they were soning and general intelligence. For short-term mem- classified as "untreated" and used as a control group. ory, children were asked to try and repeat a gradually Height, weight, and migration data was collected increasing string of numbers back to the interviewer, from more than 20,000 children at all the deworming either forwards or backwards. A decade later, children who were infants when Children who were infants when their siblings received their siblings were treated for worms showed the deworming medication scored much better on tests of large gains in cognitive skills, reasoning than children who were around three years old when deworming was introduced in their communities. *Bairdt Sarah, Joan Hamory Hicks, Michael Kremer, and Edward Miguel (2015). "Worms at Work: Long-Run Impacts of Child Health Gains." Unpublished Manuscript. The cognitive gains were comparable to a half year of People who had the most physical contact with schooling. Infants in the communities where deworming infants were an important link through which took place faced a lower risk of infection during a crucial infants and toddlers received the health benefits period when brains and bodies develop. This likely helped of deworming. their development, giving them a boost that was reflected in tests of their cognitive abilities years later. The physical contact may have been key to why young children were either more, or less, vulnerable to worms. The biggest gain was seen among children who In other words, the infants could have faced greater risk of had older siblings in primary schools where the infection if the person in physical contact with them had deworming program in the community took place. worms, and lower risk if that person was free of worms. The gains were nearly twice as large for children who had an older sibling in school at the time when compared with children who lived in the community where the deworm- ing was happening but didn't have older siblings who would have received the treatment in school. Identifying which children had older siblings in school at the time wasn't always easy. Children gener- ally weren't sure of the ages of their older siblings. As a result, the evaluation assumed that a child with three or more older siblings who had gone to primary school had at least one sibling who was part of the deworm- ing program. The larger cognitive gains among children with older siblings in school makes sense because fewer worms among people who live together reduces the Deworming produced the biggest cognitive gains chance of infection. among children less than a year old... Infants with older sisters in school appeared to The largest gains from community-wide deworming of show the biggest cognitive gains. primary school children were found among children who were under the age of one when the deworming took The larger impact for children with older sisters could re- place. The impact on children between the ages of one flect that girls more often than boys are asked to care for and three years old proved to be no different statistically younger siblings. This care pattern is common across many from the impact of community deworming on much cultures, and stands out in Kenya in particular. In west- older children. In other words, there were no big gains ern Kenya, where the predominant ethnic group is Luhya, in cognitive skills, though there may still be school atten- older female siblings are more than twice as likely as male dance gains and long-term health gains from deworming siblings to care for infants. later in childhood. However there was no effect on physical ... and it's both cost-effective and a potential development. revenue booster for governments. Deworming of children in the community didn't show any A variety of studies have calculated that deworming a child impact at the time on physical development and likewise costs about $0.59 a year. If the cognitive gains made by in- didn't have an impact on those who were infants at the time. fants exposed to deworming through their older siblings lead The follow-up measured height, height-for-age, and stunt- to increased earnings then governments stand to gain addi- ing, and didn't find any impact. tionally from increased tax revenue and productivity. This policy note is based on "Exploiting Externalities to Estimate the Long-Term Effects of Early Childhood Deworming," Owen Ozier (World Bank's Development Research Group), October 2014, Policy Research Working Paper 7052.Available at: http://www-wds.worldbank.org/external/default/WDSContentServer/WDSP/IB /2014/10/01/00015834920141001145539/Rendered/PDF/WPS7052.pdf Children who were infants when deworming was administered ing occurred, especially if that sibling was female. The to older children in primary school scored higher on cognitive findings reinforce evidence that children's cognitive de- tests a decade later, even though they had not received the de- velopment is particularly active during early childhood. worming drugs at that time. The results are significant, sug- The results also provide evidence that an inexpensive gesting deworming does have a long-term impact on cogni- program like deworming can deliver big, lasting ben- tion-contrary to earlier findings-and underscoring the value efits. Together with other recent studies, this evaluation of long-term follow-up evaluations. In this case, the infants helps paint a complete picture of the long-term benefits benefited from fewer worms in the community, reducing their of deworming in developing countries. It also points to risk of infection during a critical period in development. the usefulness of long term follow-up studies to truly The biggest gains occurred among infants who had understand a program's impact. an older sibling in primary school when the deworm- The Strategic Impact Evaluation Fund, part of the World Bank Group, supports and disseminates research evaluating the impact of development projects to help alleviate poverty. The goal is to collect and build empirical evidence that can help governments and development organizations design and implement the most appropriate and effective policies for better educational, health and job opportunities for people in developing countries. For more information about who we are and what we do, go to: http://www.worldbank.org/sief. The Evidence to Policy note series is produced by SIEF with generous support from the British government's Department for International Development. THE WORLD BANK THE WORLD BANK, STRATEGIC IMPACT EVALUATION FUND 1818 H STREET, NW WASHINGTON, DC 20433 Produced by the Strategic Impact Evaluation Fund Series Editor and Writer: Aliza Marcus