Rural Gambian Villages Research Articles

Does ethnic diversity decrease economic interactions? Evidence from exchange networks in rural Gambia

AbstractUsing a unique dataset collected in 59 rural Gambian villages, we study how ethnic heterogeneity is related to the structure of four economic exchange networks: land, labour, inputs and credit. We find that different measures of village‐level ethnic fragmentation are mostly uncorrelated with network structure. At a more disaggregated level, household heads belonging to ethnic minorities are not less central than those from the predominant ethnicity in any of the networks and, at the dyadic level, the fact that two households share ethnicity is not an economically significant predictor of link formation. Our results indicate that, in the particular setting of our study, the structure of the exchange networks is better defined by other variables than ethnicity and that ethnic heterogeneity is unlikely to be a driver for sub‐optimal economic exchanges.

Growth faltering in rural Gambian children after four decades of interventions: a retrospective cohort study

SummaryBackgroundGrowth faltering remains common in children in sub-Saharan Africa and is associated with substantial morbidity and mortality. Due to a very slow decline in the prevalence of stunting, the total number of children with stunting continues to rise in sub-Saharan Africa. Identification of effective interventions remains a challenge.MethodsWe analysed the effect of 36 years of intensive health interventions on growth in infants and young children from three rural Gambian villages. Routine growth data from birth to age 2 years were available for 3659 children between 1976 and 2012. Z scores for weight-for-age, length-for-age, weight-for-length, mid-upper-arm circumference, and head circumference were calculated using the WHO 2006 growth standards. Seasonal patterns of mean Z scores were obtained by Fourier regression. We additionally defined growth faltering as fall in Z score between 3 months and 21 months of age.FindingsWe noted secular improvements in all postnatal growth parameters (except weight-for-length), accompanied by declines over time in seasonal variability. The proportion of children with underweight or stunting at 2 years of age halved during four decades of the study period, from 38·7% (95% CI 33·5–44·0) for underweight and 57·1% (51·9–62·4) for stunting. However, despite unprecedented levels of intervention, postnatal growth faltering persisted, leading to poor nutritional status at 24 months (length-for-age Z score −1·36, 95% CI −1·44 to −1·27, weight-for-age Z score −1·20, −1·28 to −1·11, and head circumference Z score −0·51, −0·59 to −0·43). The prevalence of stunting and underweight remained unacceptably high (30·0%, 95% CI 27·0–33·0, for stunting and 22·1%, 19·4 to 24·8, for underweight).InterpretationA combination of nutrition-sensitive and nutrition-specific interventions has achieved a halving of undernutrition rates, but despite these intensive interventions substantial growth faltering remains. We need to understand the missing contributors to growth faltering to guide development of new interventions.FundingUK Medical Research Council, UK Department for International Development.

Rope Pump Modifications to Reach Greater Depths: A Service Project for Clean Water in The Gambia

Rope pumps are a locally adaptable and relatively simple technology for water retrieval that are easy to understand and repair and perform well with respect to water quality. Concern Universal - an NGO with offices in Banjul, The Gambia - was introducing the rope pump into The Gambia and needed assistance in designing a rope pump that could lift water from greater depths. Modifications to the rope pump would be needed, which became the basis of an opportunity for a student service-learning project / capstone design experience for students to develop a solution. More specifically, the design criteria were to develop an affordable, easy to use rope pump that could be used to pump water from a depth of 30 m to a storage tank 5 m above ground with a constraint of human power by a single operator. A team of undergraduate students and faculty designed, built and tested a rope pump that was similar to those used in rural Gambian villages. The team’s rope pump design, analyze, build and test process is described in this paper. The design solution began by first modeling the rope pump in a user-defined MATLAB routine to effectively determine the effects of parameters and constraints. A parametric study, where pipe diameter, number of pistons per meter of rope length, well depth and input rotational speeds were varied, was conducted. These results provide a range of conditions for using a rope pump at various depths and provided a basis for designing a pump. Experimental tests were conducted, and the results were compared to theoretical predictions. Experimental results for flow rate were within 3-18% of predicted values. To meet the client’s needs, it was determined that a rope pump with 1.27 cm (0.5 in) diameter piping, two pistons per meter, and a belt drive with gears of ratio of 1.5:1 to increase torque could raise water 35 m using operator under human-power. Additionally, alternative forms of power that would be available to the region are briefly investigated and discussed as potential future work, although further development was beyond the scope of this design project.

Missing Links, Missing Markets: Internal Exchanges, Reciprocity and External Connections in the Economic Networks of Gambian Villages

A unique dataset of social and economic networks collected in 60 rural Gambian villages is used to study the ways in which households with links outside the village (that are considered as a proxy for market connections) behave in the locally available exchange networks for land, labor, input and credit. Using measures gleaned from the social network analysis literature, the econometric results at both household and link (dyadic) level provide evidence of: (i) substitutability between internal and external links, and (ii) substitutability between internal reciprocation and external links. These findings provide support for the transformation process of primitive economies described in a long tradition of anthropological work as well as recent theoretical models.

Long‐Term Protection against Carriage of Hepatitis B Virus after Infant Vaccination

Carriage of hepatitis B virus (HBV) is a major risk factor for liver cirrhosis and hepatocellular carcinoma. Infant vaccination has been effective in preventing horizontal transmission during early childhood. It is unknown whether protection is maintained into early adulthood. In 1984, early childhood vaccination was introduced in 2 rural Gambian villages. In 2003, serological assessment of 81.5% of 1,350 eligible participants 1-24 years old was done, to determine vaccine efficacy against infection and carriage. Overall vaccine efficacy against infection and carriage was 83.4% (95% confidence interval [CI], 79.8%-86.6%) and 96.5% (85% CI, 93.9%-98.9%), respectively. Vaccine efficacy against infection was similar when restricted to primary responders (85.3%), but a significant effect of peak antibody concentration was found. Both vaccine efficacy and levels of hepatitis B surface antibody (anti-HBs) decreased with age, resulting in a vaccine efficacy against infection and carriage among 20-24-year-old participants of 70.9% (95% CI, 60.4%-80.5%) and 91.1% (95% CI, 75.8%-100%), respectively. Fifteen years after vaccination, fewer than half of the vaccinees had detectable anti-HBs. The prevalence of carriage in the unvaccinated population was similar to the prevalence 20 years earlier. HBV vaccination early during life can provide long-lasting protection against carriage, despite decreasing antibody levels. The role played by subclinical boosting and the necessity of a booster need to be evaluated.

Fifty‐year mortality trends in three rural African villages

To determine differential improvements in mortality rates according to age, and to discuss differences in neonatal and post-neonatal mortality rates, using longitudinal data from the past 50 years in three rural Gambian villages. All villagers whose date of birth was recorded were followed up until death or October 1997. A Lexis expansion was performed to categorize age: early neonatal, late neonatal, infant, 1-4 years, 5-14 years and 15 or more years. Calendar time was divided into three periods -- prior to 1975, 1975-1984 and after 1985, representing different levels of clinical care. Cox regression and likelihood-ratio test were used to model the hazards ratios. There were 3981 subjects included in the analysis with a total of 59 002 person-years follow-up. There was a dramatic decrease in neonatal (44 to 15), infant (162 to 36) and under-five mortality rates (397-66 per 1000) from pre-1975 to the present. The disproportionate decrease in the mortality rates means that neonatal deaths accounted for a greater percentage of post-natal deaths in later years. There was a marked seasonality in mortality rates with significantly more deaths in the 'hungry' season prior to 1975 (odds = 1.87; 95% CI = 1.62-2.17) and from 1975 to 1984 (odds = 1.84; 95% CI = 1.34-2.53). This seasonality of death has diminished in recent years (odds = 1.23; 95% CI = 0.85-1.76). Our analysis indicates a dramatic reduction in mortality rates and an attenuation in the seasonality of death. It is likely that the efficient implementation of basic currently available health measures was one of the key elements in achieving such a major reduction in mortality.

Intestinal inflammation measured by fecal neopterin in Gambian children with enteropathy: association with growth failure, Giardia lamblia, and intestinal permeability.

Investigate whether fecal neopterin concentration (a potential marker of gut inflammation) in Gambian children with enteropathy was associated with growth failure. Secondary outcome measures tested the associations between Giardia lamblia infestation, fecal neopterin and lactulose mannitol absorption ratio(L:M), a measure of intestinal permeability. Seventy-two children had height and weight measured every 6 to 8 weeks until 15 months of age in a rural Gambian village. L:M ratio, a measure of small intestinal permeability and fecal neopterin were measured at these times. Stool was examined by immunofluorescence and light microscope for Giardia cysts. Long-term height and weight gains were negatively associated with mean subject fecal neopterin concentration (r = -0.29 and -0.36, respectively; P < 0.001). There was no correlation between fecal neopterin and intestinal permeability or history of diarrhea. Of 72 children studied, 19 had Giardia cysts in stool and 38 had negative stool examinations. Infected children had a mean of 0.7 days of diarrhea/week (95% confidence interval [CI], 0.31-1.03) versus 0.8 days/week (95% CI, 0.71-0.85) in uninfected children. No difference in growth was detected between those with positive or negative fecal smears. Mean L:M ratio was the same in both groups (0.31; 95% CI, 0.26-0.34). Consistent with the theory that intestinal inflammation in tropical infants may impair growth, fecal neopterin concentrations were inversely associated with growth. Factors other than Giardia are causing enteropathy and growth failure in Gambian infants.

Intestinal Inflammation Measured by Fecal Neopterin in Gambian Children With Enteropathy: Association With Growth Failure, Giardia lamblia, and Intestinal Permeability

ABSTRACTObjectives:Investigate whether fecal neopterin concentration (a potential marker of gut inflammation) in Gambian children with enteropathy was associated with growth failure. Secondary outcome measures tested the associations between Giardia lamblia infestation, fecal neopterin and lactulose mannitol absorption ratio(L:M), a measure of intestinal permeability.Methods:Seventy‐two children had height and weight measured every 6 to 8 weeks until 15 months of age in a rural Gambian village. L:M ratio, a measure of small intestinal permeability and fecal neopterin were measured at these times. Stool was examined by immunoflorescence and light microscope for Giardia cysts.Results:Long‐term height and weight gains were negatively associated with mean subject fecal neopterin concentration (r = −0.29 and −0.36, respectively; P &lt; 0.001). There was no correlation between fecal neopterin and intestinal permeability or history of diarrhea. Of 72 children studied, 19 had Giardia cysts in stool and 38 had negative stool examinations. Infected children had a mean of 0.7 days of diarrhea/week (95% confidence interval [CI], 0.31–1.03) versus 0.8 days/week (95% CI, 0.71–0.85) in uninfected children. No difference in growth was detected between those with positive or negative fecal smears. Mean L:M ratio was the same in both groups (0.31; 95% CI, 0.26–0.34).Conclusions:Consistent with the theory that intestinal inflammation in tropical infants may impair growth, fecal neopterin concentrations were inversely associated with growth. Factors other than Giardia are causing enteropathy and growth failure in Gambian infants.

Human and other faeces as breeding media of the trachoma vector Musca sorbens.

The fly Musca sorbens Wiedemann (Diptera: Muscidae) apparently transmits Chlamydia trachomatis, causing human trachoma. The literature indicates that M. sorbens breeds predominantly in isolated human faeces on the soil surface, but not in covered pit latrines. We sought to identify breeding media of M. sorbens in a rural Gambian village endemic for trachoma. Test breeding media were presented for oviposition on soil-filled buckets and monitored for adult emergence. Musca sorbens emerged from human (6/9 trials), calf (3/9), cow (3/9), dog (2/9) and goat (1/9) faeces, but not from horse faeces, composting kitchen scraps or a soil control (0/9 of each). After adjusting for mass of medium, the greatest number of flies emerged from human faeces (1426 flies/kg). Median time for emergence was 9 (inter quartile range = 8-9.75) days post-oviposition. Of all flies emerging from faeces 81% were M. sorbens. Male and female flies emerging from human faeces were significantly larger than those from other media, suggesting that they would be more fecund and live longer than smaller flies from other sources. Female flies caught from children's eyes were of a similar size to those from human faeces, but significantly larger than those from other media. We consider that human faeces are the best larval medium for M. sorbens, although some breeding also occurs in animal faeces. Removal of human faeces from the environment, through the provision of basic sanitation, is likely to greatly reduce fly density, eye contact and hence trachoma transmission, but if faeces of other animals are present M. sorbens will persist.

Prenatal or early postnatal events predict infectious deaths in young adulthood in rural Africa.

Research over the past decade has suggested that prenatal and early postnatal nutrition influence the risk of developing chronic degenerative diseases up to 60 years later. We now present evidence that risk of death from infectious diseases in young adulthood is similarly programmed by early life events. In three rural Gambian villages, affected by a marked annual seasonality in diet and disease, we have kept detailed demographic, anthropometric and health records since 1949. Fate was known with certainty for 3,162 individuals (2,059 alive/1,103 dead, most dying in childhood). For this case-control analysis of antecedent predictors of premature mortality, all adult deaths (n = 61) were paired with two randomly selected controls matched for sex and year of birth. Mean age at death was 25 (SD: 8) years. Adult death was associated with a profound bias in month of birth with 49 cases born in the nutritionally-debilitating hungry season (Jul-Dec) versus 12 in the harvest season (Jan-Jun). Relative to harvest season the hazard ratio for early death in hungry-season births rose from 3.7 (for deaths >14.5 years, P = 0.000013) to 10.3 (for deaths >25 years, P = 0.00002). Anthropometric and haematological status at 18 months of age was identical in cases and controls, indicating an earlier origin to the defect. Most deaths for which cause was known had a definite or possible infectious aetiology; none were from degenerative diseases of affluence. Early life exposures, correlated with season of birth, strongly influence susceptibility to fatal infections in young adulthood. The evidence suggests that nutritionally-mediated intrauterine growth retardation may permanently impair the development of immune function.

Impact of community-based mass treatment for trachoma with oral azithromycin on general morbidity in Gambian children.

The World Health Organization has recently targeted the elimination of trachoma as a public health problem by the year 2020. Community-based treatment with antibiotics, including oral azithromycin, is recommended for severely affected communities. The incidence of adverse effects after azithromycin treatment is not known in trachoma endemic communities. We compared the effects of azithromycin with those of topical tetracycline given as mass treatment for trachoma on childhood morbidity in eight rural Gambian villages. The entire population of four villages received oral azithromycin suspension (Zithromax, Pfizer) in doses of 20 mg/kg on Days 1, 8 and 15; the other four villages received topical tetracycline eye ointment for 42 days. Morbidity surveys of subjects 3 months to 14 years old were conducted on Days 0, 7, 14, 21 and 28. Of the 804 subjects recruited complete follow-up data were available on 791 (412 azithromycin, 379 tetracycline). Fever and headache were the most common complaints. Apart from cough other symptoms were equally prevalent in both groups at baseline. The azithromycin group had 20% fewer illness, fever and headache episodes and 40% fewer diarrhea and vomiting episodes at follow-up than did the tetracycline group. Azithromycin treatment for trachoma had favorable short term effects on childhood morbidity in rural Gambian villages, particularly in the high malaria transmission season, and adverse effects were not a problem.

Energy-sparing strategies to protect human fetal growth

Our purpose was to test whether energy-sensitive adjustments in gestational metabolism, previously observed in studies of Gambian and British women, are a general phenomenon and to define the nutritional factors that direct them. Retrospective analysis of data on basal metabolic rate and fat deposition in 360 pregnancies from 10 studies in a wide range of nutritional settings was performed. The energy costs of pregnancy varied widely between different communities: maintenance costs from -45 to +210 MJ, fat deposition from -23 to +267 MJ, and total energy costs from -20 to +523 MJ. Total costs were correlated with prepregnancy fatness (r = 0.80, p < 0.01) and pregnancy weight gain (r = 0.94, p < 0.001). Marginally nourished women conserved energy by suppressing metabolic rate and by gaining little fat. The energy needs of pregnancy are modulated over a wide range in response to maternal energy status. This may be an important means of protecting fetal growth.

Is cow's milk suitable for the dietary supplementation of rural Gambian children? 1. Prevalence of lactose maldigestion.

To define the age-related prevalence of lactose maldigestion (LM), 218 children aged 13-72 months from a rural Gambian village were studied using a lactose breath hydrogen test. There was a significant rise in LM from 21% to 76% between the 2nd and 3rd-5th years of life (p < 0.001). Only eight children had diarrhoea within 2 weeks before the test. Diarrhoea and abdominal discomfort followed in only seven children (3%). There was no difference in mean time of introduction of supplementary diet or cessation of breastfeeding between children aged 12-36 months with lactose digestion and LM. There was a greater proportion of children with normal lactose digestion than with LM in those still receiving breast milk (85% vs 15%), and a greater proportion of LM in the fully weaned group (63% vs 37%) (p < 0.001). There was no relation between weight-for-age or weight-for-height and the ability to digest lactose. The ability to digest lactose is lost in the majority of children during the 2nd year, coincident with the cessation of breastfeeding, but is not a major factor associated with growth failure thereafter.

Raised urinary secretory IgA in chronic diarrhoea.

Secretory IgA outputs in urine have been measured in 24 malnourished Gambian children who had been admitted to hospital with chronic diarrhoea and in 43 children from a rural Gambian village. Village children of poor nutritional state (less than or equal to 74% weight for age compared with the National Center for Health Statistics reference curve) had secretory IgA outputs that were only one third of those of better nourished individuals. In contrast, the patients with chronic diarrhoea had secretory IgA outputs that were significantly raised compared with village children, regardless of nutritional state. These results demonstrate that secretory IgA production in the urinary tract can be stimulated by intestinal disease, suggesting that malnourished children are able to mount a response to mucosal infection and supporting the hypothesis of a common secretory immune system.

Seasonal variations in the nutritional status of urban Gambian children.

1. Children aged 6-35 months in an urban community in The Gambia, West Africa, were weighed and their lengths measured at four surveys over an 18-month period, twice towards the end of the rains, and twice during the dry season. 2. Relative to international standards, height-for-age deteriorated steadily with age, while weight-for-age fell sharply in the second-half of infancy but showed no further deterioration from 12 to 35 months of age. 3. Height-for-age showed little seasonal variation, but weight-for-age and weight-for-height were lower at the end of the rains than during the dry season. Weight and height velocities were much lower during the rains than in the dry season, with more than 20% of the children losing weight during the rains. Possible reasons for these seasonal variations are discussed. Compensatory weight gain in the dry season exceeded the velocity expected from the standards in children aged 12 months or more, but height velocity fell below the standards all year. 4. The results are compared with previous findings from Keneba, a rural Gambian village. Weight velocity during the dry season was similar in the two communities, but the village children experienced a sharper decline in weight gain during the rains. 5. These results suggest that seasonal ecological factors may seriously influence the nutritional status of children living in an urban environment with adequate availability of food.

Susceptibility of Plasmodium falciparum in The Gambia to pyrimethamine, Maloprim and chloroquine

A five-year malaria chemoprophylaxis study has begun with Maloprim in children aged three months to five years and pregnant women in a population of 13,000 in the area of Farafenni, The Gambia. Sensitivity of Plasmodium falciparum to pyrimethamine, Maloprim and chloroquine was assessed in vivo and in vitro in rural Gambian villages before drug intervention. 569 children aged one to seven years inclusive were sampled at the end of the wet season of 1982; 46% had positive blood films. All afebrile children were treated with a single dose of one of the antimalarials under study. Febrile children were treated with chloroquine. 109 infected children were retested 7 to 10 days after treatment and none showed asexual parasitaemia. 83 micro in vitro tests were successfully performed from fingerprick blood samples and the results confirmed the in vivo study. Pyrimethamine in combination with dapsone, in the proportion present in Maloprim, i.e., 1:8, showed a synergistic effect, the mean effective dose of pyrimethamine being reduced 13 times at the 50% inhibitory level.

CHANGES IN MATERNAL AND CHILD MORTALITY RATES IN THREE ISOLATED GAMBIAN VILLAGES OVER TEN YEARS

As an adjunct to the general nutrition research programme, the MRC Dunn Nutrition Unit has provided for the past 10 years a continuous medical service to three adjacent rural Gambian villages. There have been substantial reductions in annual childhood mortality rates. Perinatal mortality fell from 109·6 to 45·5 per 1000 births, infant mortality from 148·5 to 24·5 per 1000 live births, and mortality in children aged 1-4 years from 109·1 to 13·3 per 1000. There have been no pregnancy-related maternal deaths in the community for 8 years; 16 could have been expected given current estimates of maternal mortality elsewhere in rural Gambia. Of all the health and nutritional interventions introduced the single most important factor has apparently been the on-the-spot, 24 h availability of a physician or qualified midwife.

Seasonal variations in plasma retinol and carotenoid levels in rural Gambian women

Plasma carotenoid levels exhibited a major seasonal variation in pregnant and lactating women in Keneba, a rural Gambian village. This is probably due mainly to the seasonally related contribution of mangoes, which are a major dietary component during May and June, but are essentially unavailable for the remainder of the year. Plasma retinol levels, on the other hand, exhibited much less seasonal variation, although a trend towards higher levels in May and June was just discernible. Plasma retinol levels were significantly lower than those observed in a group of pregnant and lactating women living in the UK.

Riboflavin status in infants born in rural Gambia, and the effect of a weaning food supplement

Riboflavin status was measured in infants between birth and two years of age, by the erythrocyte glutathione reductase (NAD(P)H 2: glutathione oxidoreductase, EC 1.6.4.2) test on finger-prick blood samples. The infants were living in three rural Gambian villages: Keneba, Manduar and Kanton Kundar; those in Keneba were receiving a weaning food supplement between three and 12 months, which provided 0.15 to 0.20 mg riboflavin per day, in addition to their normal intake from breast milk and locally available weaning foods, which provided 0.13 to 0.21 mg/day over the same age range. On the basis of currently accepted criteria of biochemical normality, the unsupplemented infants were born deficient and, in the absence of a supplement, remained so throughout their first two years of life, with only a minor, short-lived improvement during the first few months. In the supplemented group, however, riboflavin status fell within normal limits for the duration of the supplement, but rapidly deteriorated again once the supplement was withdrawn. It is concluded that infants born to deficient mothers are usually deficient at birth, and remain so throughout suckling and weaning on to locally available foods. The daily requirement, to achieve satisfactory biochemical status, is thus greater than 0.13 to 0.21 mg/day, and probably approaches 0.4 mg/day, for most individuals up to the age of one year.

Seasonal variations in ascorbic acid status and breast milk ascorbic acid levels in rural Gambian women in relation to dietary intake

Vitamin C intakes from mangoes and oranges, and plasma and breast milk ascorbic acid concentrations were measured at regular intervals in a cohort of pregnant and lactating women in Keneba and Manduar, two neighbouring rural Gambian villages. Extremely wide seasonal variations in plasma ascorbic acid levels were observed, the peak during the mango season in May and June attaining mean levels of 1·4 mg/dl, while the lowest levels, averaging only 0·2 mg/dl, were observed during the rainy season, during September and October. Parallel, but less pronounced variations were observed in breast milk ascorbate levels. A vitamin-fortified milk and biscuit supplement, given first to the lactating, and later to the pregnant, mothers in Keneba, which provided about 35 mg ascorbic acid per day, failed to produce any major improvement in plasma ascorbic acid levels during the rainy season, although there was some evidence for an improvement in breast milk levels. It is therefore likely that considerably greater intakes are required to maintain satisfactory maternal circulating levels and biochemical status during this critical period.