Essays on immigrant integration, remittances, and agricultural policies in developing countries

This thesis is organised into two main parts; the first part relates to immigrants - their economic integration in the host country and their role in mitigating the effects of disasters in their home countries through remittances. The second part of this thesis is a policy evaluation of the effect of export bans on prices and food security. In the first chapter, I describe and investigate the role of informal institutions in the labour market integration of immigrants. I exploit a law in France, that was implemented in 1981 when the socialist government came to power, which allowed individuals including immigrants to organise themselves into groups or associations. North African immigrants mainly originating from Morocco, Tunisia and Algeria capitalised on this law to establish several community based organisations in various locations in France. A particular type that is of interest to this paper are those engaged in the economic integration of immigrants. These organisations mainly seek to assist immigrants in improving their labour market outcomes through the provision of language training classes, CV preparations, information about job opportunities and so on. I collect information on all such organisations registered in France between 1996 - the year in which the first organisation was recorded to 2012. I combine it with data from the French labour force survey between 1990 and 2012 to asses its effect on labour force participation, employment, and earnings of these immigrants using a difference-in-differences strategy combined with a Heckman selection model. I find that these organisations improve labour force participation rates and the probability of obtaining a job for Maghreb women without a corresponding reduction in earnings. %The impact of these organisations is driven by the larger impact on women, people who had stayed long in the destination country levels of education and immigrants arriving newly. In the second chapter, using monthly remittance flows from Italy to a number of developing countries, we investigate the impact of natural disasters on remittances with the aim of improving identification by adapting an event study design. This allows us to flexibly document the immediate response of remittances and to test if there exists any anticipatory or lag effect in the way in which remittances responds to natural disasters. The use of monthly data further allows us to clearly distinguish the response of remittances depending on the nature of the disaster. Our analyses uses various alternative specifications of the disaster measure and varying lengths of the response period. Our findings reveal that remittances increases significantly in the months following the occurrence of a disaster peaking at an average of 2.7 percent, four months following the disaster and averaging about 2 percent over the 12 months window. Controlling for disasters occurring outside our sample period to eliminate any remaining trend in remittance flows and capture any potential dynamics that might be attributed to disasters does not affect neither the magnitude or significance of our coefficients, rather it allows for a clear breakthrough in the dynamics of remittance flows around the time of the disaster. All our findings are robust to controlling for other shocks in the receiving country such as the trend and cyclical fluctuation in the monthly terms of trade, monthly rainfall and temperature as well as a proxy for the economic condition in the sending country and a host of country and time fixed effects. Further carrying out several heterogeneity analyses reveal that the response of remittances is higher for countries with a relatively larger stock of immigrants and that the observed effect is largely driven by the response to disasters occurring in upper middle-income developing countries. We also find a differential response in timing based on the nature of the disaster, slow or sudden. %, for instance, restricting our analyses to only countries with a relatively larger stock of immigrants, we find that the response of remittances is much higher for these countries. When we dis-aggregate in terms of countries level of development, we find that the observed effect is largely driven by the response to disasters occurring in upper middle-income developing countries. We also find a differential response in timing based on the nature of the disaster. Finally, in the third chapter I conduct a policy evaluation of the effect of an export ban on maize instituted by the Malawian government. Using monthly price and annual harvest data from the Malawian ministry of agriculture, I investigate the effect of the policy on maize prices and its volatility as well as on maize production. I extend this literature by further distinguishing the export bans based on whether they are internally induced - supply shock or externally induced demand shock. To account for the endogeneity of the ban, I Use monthly rainfall data and global maize prices as instruments for the ban. I find the export bans on aggregate to be unsuccessful in preventing a rise in maize prices, though to some extent it stabilises maize prices. Once we distinguish the ban based on factors inducing it, we find two opposing results. First, that export bans are ineffective against a demand induced export ban but very effective against a supply induced export ban. Based on anecdotal evidence, it seems that traders hoard these goods in anticipation of a lifting of the ban to get access to better prices for their products, hence the ineffectiveness f the ban in the midst of rising global prices. Furthermore, there is also evidence that despite the ban, positive quantities of maize continues to be exported illegally rendering the policies ineffective and thereby failing to mitigate the effect of the shock on prices. In terms of food security, we use the share of acreage dedicated to maize production as a proxy for food security. Here, I argue that the ad-hoc nature in which the policy is imposed and lifted creates a source of uncertainty in maize prices which may have consequent effect on farmers maize cultivation decisions, especially for large scale commercial farmers. Estimating a dynamic system GMM model, I find that the ban induces farmers to reduce the acreage share allocated to maize production. However, since we do not observe the variety of maize being cultivated or the inputs used in production, we cannot really conclude on whether there is a decline in maize production or a shift towards cultivating higher yielding maize varieties

Trypanosomosis in The Gambia: prevalence in working horses and donkeys detected by whole genome amplification and PCR, and evidence for interactions between trypanosome species

<p>Abstract</p> <p>Background</p> <p>The Gambia has an increasing population of <it>equidae </it>largely used for agriculture and transportation. A review of cases at The Gambian Horse and Donkey Trust (GHDT) indicated that a common reason for presentation is a poorly defined medical condition often attributed to trypanosomosis. There are few reports describing the prevalence or the range of clinical signs associated with infection with different species of trypanosomes in horses and donkeys, but given the importance of these animals, the role of trypanosomosis requires investigation.</p> <p>Results</p> <p>In total 241 animals from the Central River Division in The Gambia (183 horses and 58 donkeys) were screened using Whole Genome Amplification (WGA) followed by trypanosome species identification using polymerase chain reaction (PCR). The results indicated overall trypanosome prevalence of 91%; with an infection rate of 31% for <it>Trypanosoma congolense </it>Savannah, 87% for <it>Trypanosoma vivax </it>and 18% for <it>Trypanosoma brucei </it>sp. Multiple species were present in 43% of infections. Microscopy had a good specificity (100%) and positive predictive value (100%) for trypanosome detection, but the sensitivity (20%) and negative predictive value (10.5%) were low relative to PCR-based diagnosis.</p> <p>Infection with <it>T congolense </it>showed the greatest negative effect on packed cell volume (PCV), while infection with <it>T. brucei </it>sp also had a significant, although lesser, negative effect on PCV. In addition, cases positive by microscopy were associated with significantly lower PCV. However, concurrent infection with <it>T. vivax </it>appeared to cause less effect on PCV, compared to animals infected with <it>T. congolense </it>alone.</p> <p>Conclusion</p> <p>The prevalence of Trypanosomosis was high in both horses and donkeys. Infection with <it>T. congolense </it>appeared to have the greatest clinical significance, while <it>T. vivax </it>infection may be of limited clinical significance in this population. Indeed, there is evidence of <it>T. vivax </it>co-infection ameliorating the pathology caused by <it>T. congolense</it>. WGA and PCR allowed a more comprehensive analysis of field infections with the detection of infections below the threshold of microscopy, and provided indications of interactions between parasite species that would otherwise remain undetected. The study raises important questions about the epidemiology of trypanosome infection in relation to disease that require a full scale longitudinal analysis.</p

Oral iron acutely elevates bacterial growth in human serum.

Iron deficiency is the most common nutrient deficiency worldwide and routine supplementation is standard policy for pregnant mothers and children in most low-income countries. However, iron lies at the center of host-pathogen competition for nutritional resources and recent trials of iron administration in African and Asian children have resulted in significant excesses of serious adverse events including hospitalizations and deaths. Increased rates of malaria, respiratory infections, severe diarrhea and febrile illnesses of unknown origin have all been reported, but the mechanisms are unclear. We here investigated the ex vivo growth characteristics of exemplar sentinel bacteria in adult sera collected before and 4 h after oral supplementation with 2 mg/kg iron as ferrous sulfate. Escherichia coli, Yersinia enterocolitica and Salmonella enterica serovar Typhimurium (all gram-negative bacteria) and Staphylococcus epidermidis (gram-positive) showed markedly elevated growth in serum collected after iron supplementation. Growth rates were very strongly correlated with transferrin saturation (p < 0.0001 in all cases). Growth of Staphylococcus aureus, which preferentially scavenges heme iron, was unaffected. These data suggest that even modest oral supplements with highly soluble (non-physiological) iron, as typically used in low-income settings, could promote bacteremia by accelerating early phase bacterial growth prior to the induction of immune defenses

Hepcidin mediates hypoferremia and reduces the growth potential of bacteria in the immediate post-natal period in human neonates.

Septicemia is a leading cause of death among neonates in low-income settings, a situation that is deteriorating due to high levels of antimicrobial resistance. Novel interventions are urgently needed. Iron stimulates the growth of most bacteria and hypoferremia induced by the acute phase response is a key element of innate immunity. Cord blood, which has high levels of hemoglobin, iron and transferrin saturation, has hitherto been used as a proxy for the iron status of neonates. We investigated hepcidin-mediated redistribution of iron in the immediate post-natal period and tested the effect of the observed hypoferremia on the growth of pathogens frequently associated with neonatal sepsis. Healthy, vaginally delivered neonates were enrolled in a cohort study at a single center in rural Gambia (N = 120). Cord blood and two further blood samples up to 96 hours of age were analyzed for markers of iron metabolism. Samples pooled by transferrin saturation were used to conduct ex-vivo growth assays with Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli and Klebsiella pneumonia. A profound reduction in transferrin saturation occurred within the first 12 h of life, from high mean levels in cord blood (47.6% (95% CI 43.7-51.5%)) to levels at the lower end of the normal reference range by 24 h of age (24.4% (21.2-27.6%)). These levels remained suppressed to 48 h of age with some recovery by 96 h. Reductions in serum iron were associated with high hepcidin and IL-6 levels. Ex-vivo growth of all sentinel pathogens was strongly associated with serum transferrin saturation. These results suggest the possibility that the hypoferremia could be augmented (e.g. by mini-hepcidins) as a novel therapeutic option that would not be vulnerable to antimicrobial resistance. Trial registration: The original trial in which this study was nested is registered at ISRCTN, number 93854442

A novel nano-iron supplement to safely combat iron deficiency and anaemia in young children: The IHAT-GUT double-blind, randomised, placebo-controlled trial protocol.

Background: Iron deficiency and its associated anaemia (IDA) are the leading forms of micronutrient malnutrition worldwide. Here we describe the rationale and design of the first clinical trial evaluating the efficacy and safety of an innovative nano iron supplement, iron hydroxide adipate tartrate (IHAT), for the treatment of IDA in young children (IHAT-GUT trial). Oral iron is often ineffective due to poor absorption and/or gastrointestinal adverse effects. IHAT is novel since it is effectively absorbed whilst remaining nanoparticulate in the gut, therefore should enable supplementation with fewer symptoms. Methods: IHAT-GUT is a three-arm, double-blind, randomised, placebo-controlled phase II trial conducted in Gambian children 6-35 months of age. The intervention consists of a 12-week supplementation with either IHAT, ferrous sulphate (both at doses bioequivalent to 12.5 mg Fe/day) or placebo. The trial aims to include 705 children with IDA who will be randomly assigned (1:1:1) to each arm. The primary objectives are to test non-inferiority of IHAT in relation to ferrous sulphate at treating IDA, and to test superiority of IHAT in relation to ferrous sulphate and non-inferiority in relation to placebo in terms of diarrhoea incidence and prevalence. Secondary objectives are mechanistic assessments, to test whether IHAT reduces the burden of enteric pathogens, morbidity, and intestinal inflammation, and that it does not cause detrimental changes to the gut microbiome, particularly in relation to Lactobacillaceae, Bifidobacteriaceae and Enterobacteriaceae. Discussion: This trial will test the hypothesis that supplementation with IHAT eliminates iron deficiency and improves haemoglobin levels without inducing gastrointestinal adverse effects. If shown to be the case, this would open the possibility for further testing and use of IHAT as a novel iron source for micronutrient intervention strategies in resource-poor countries, with the ultimate aim to help reduce the IDA global burden. Registration: This trial is registered at clinicaltrials.gov ( NCT02941081)

Gut microbiomes from Gambian infants reveal the development of a non-industrialized Prevotella-based trophic network.

Funder: Bill &amp; Melinda Gates Foundation Grand Challenges New Interventions in Global Health awardFunder: MRC Unit The Gambia/MRC International Nutrition Group by the UK MRC and the UK Department for the International DevelopmentDistinct bacterial trophic networks exist in the gut microbiota of individuals in industrialized and non-industrialized countries. In particular, non-industrialized gut microbiomes tend to be enriched with Prevotella species. To study the development of these Prevotella-rich compositions, we investigated the gut microbiota of children aged between 7 and 37 months living in rural Gambia (616 children, 1,389 stool samples, stratified by 3-month age groups). These infants, who typically eat a high-fibre, low-protein diet, were part of a double-blind, randomized iron intervention trial (NCT02941081) and here we report the secondary outcome. We found that child age was the largest discriminating factor between samples and that anthropometric indices (collection time points, season, geographic collection site, and iron supplementation) did not significantly influence the gut microbiome. Prevotella copri, Faecalibacterium prausnitzii and Prevotella stercorea were, on average, the most abundant species in these 1,389 samples (35%, 11% and 7%, respectively). Distinct bacterial trophic network clusters were identified, centred around either P. stercorea or F. prausnitzii and were found to develop steadily with age, whereas P. copri, independently of other species, rapidly became dominant after weaning. This dataset, set within a critical gut microbial developmental time frame, provides insights into the development of Prevotella-rich gut microbiomes, which are typically understudied and are underrepresented in western populations

Gut microbiomes from Gambian infants reveal the development of a non-industrialized Prevotella-based trophic network.

Funder: Bill &amp; Melinda Gates Foundation Grand Challenges New Interventions in Global Health awardFunder: MRC Unit The Gambia/MRC International Nutrition Group by the UK MRC and the UK Department for the International DevelopmentDistinct bacterial trophic networks exist in the gut microbiota of individuals in industrialized and non-industrialized countries. In particular, non-industrialized gut microbiomes tend to be enriched with Prevotella species. To study the development of these Prevotella-rich compositions, we investigated the gut microbiota of children aged between 7 and 37 months living in rural Gambia (616 children, 1,389 stool samples, stratified by 3-month age groups). These infants, who typically eat a high-fibre, low-protein diet, were part of a double-blind, randomized iron intervention trial (NCT02941081) and here we report the secondary outcome. We found that child age was the largest discriminating factor between samples and that anthropometric indices (collection time points, season, geographic collection site, and iron supplementation) did not significantly influence the gut microbiome. Prevotella copri, Faecalibacterium prausnitzii and Prevotella stercorea were, on average, the most abundant species in these 1,389 samples (35%, 11% and 7%, respectively). Distinct bacterial trophic network clusters were identified, centred around either P. stercorea or F. prausnitzii and were found to develop steadily with age, whereas P. copri, independently of other species, rapidly became dominant after weaning. This dataset, set within a critical gut microbial developmental time frame, provides insights into the development of Prevotella-rich gut microbiomes, which are typically understudied and are underrepresented in western populations

Hormonal Correlates and Predictors of Nutritional Recovery in Malnourished African Children.

Background: Malnourished children show variable growth responses to nutritional rehabilitation. We aimed to investigate whether these differences could be explained by variations in growth and energy-regulating hormones. Methods: Quasi-experimental study: Children aged 6-24 months in rural Gambia were recruited to controls if weight-for-height z-score (WHZ) > -2 (n = 22), moderate acute malnutrition if WHZ  -3 (n = 18) or severe acute malnutrition if WHZ < -3 (n = 20). Plasma hormone and salivary CRP levels were determined by ELISA. Results: In univariable analyses, increases in weight-for-age z-score (WAZ) in malnourished children were positively correlated with insulin (F-ratio 7.8, p = 0.006), C-peptide (F-ratio 12.2, p < 0.001) and cortisol (F-ratio 5.0, p = 0.03). In multivariable analysis, only baseline C-peptide (F-ratio 7.6, p = 0.009) predicted the changes in WAZ over 28 days of interventions. Conclusion: In rural Gambian, malnourished children, although it cannot be used in isolation, baseline C-peptide was a predictor of future response to rehabilitation

Respiratory infections drive hepcidin-mediated blockade of iron absorption leading to iron deficiency anemia in African children.

Iron deficiency anemia (IDA) is the most prevalent nutritional condition worldwide. We studied the contribution of hepcidin-mediated iron blockade to IDA in African children. We measured hepcidin and hemoglobin weekly, and hematological, inflammatory, and iron biomarkers at baseline, 7 weeks, and 12 weeks in 407 anemic (hemoglobin < 11 g/dl), otherwise healthy Gambian children (6 to 27 months). Each child maintained remarkably constant hepcidin levels (P < 0.0001 for between-child variance), with half consistently maintaining levels that indicate physiological blockade of iron absorption. Hepcidin was strongly predicted by nurse-ascribed adverse events with dominant signals from respiratory infections and fevers (all P < 0.0001). Diarrhea and fecal calprotectin were not associated with hepcidin. In multivariate analysis, C-reactive protein was the dominant predictor of hepcidin and contributed to iron blockade even at very low levels. We conclude that even low-grade inflammation, especially associated with respiratory infections, contributes to IDA in African children

Interactions between fecal gut microbiome, enteric pathogens, and energy regulating hormones among acutely malnourished rural Gambian children.

BACKGROUND: The specific roles that gut microbiota, known pathogens, and host energy-regulating hormones play in the pathogenesis of non-edematous severe acute malnutrition (marasmus SAM) and moderate acute malnutrition (MAM) during outpatient nutritional rehabilitation are yet to be explored. METHODS: We applied an ensemble of sample-specific (intra- and inter-modality) association networks to gain deeper insights into the pathogenesis of acute malnutrition and its severity among children under 5 years of age in rural Gambia, where marasmus SAM is most prevalent. FINDINGS: Children with marasmus SAM have distinct microbiome characteristics and biologically-relevant multimodal biomarkers not observed among children with moderate acute malnutrition. Marasmus SAM was characterized by lower microbial richness and biomass, significant enrichments in Enterobacteriaceae, altered interactions between specific Enterobacteriaceae and key energy regulating hormones and their receptors. INTERPRETATION: Our findings suggest that marasmus SAM is characterized by the collapse of a complex system with nested interactions and key associations between the gut microbiome, enteric pathogens, and energy regulating hormones.  Further exploration of these systems will help inform innovative preventive and therapeutic interventions. FUNDING: The work was supported by the UK Medical Research Council (MRC; MC-A760-5QX00) and the UK Department for International Development (DFID) under the MRC/DFID Concordat agreement; Bill and Melinda Gates Foundation (OPP 1066932) and the National Institute of Medical Research (NIMR), UK. This network analysis was supported by NIH U54GH009824 [CLD] and NSF OCE-1558453 [CLD]