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- Assey, Vincent D., et al.
(författare)
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Improved salt iodation methods for small-scale salt producers in low-resource settings in Tanzania
- 2009
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 9, s. 187-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Universal salt iodation will prevent iodine deficiency disorders (IDD). Globally, salt-iodation technologies mostly target large and medium-scale salt-producers. Since most producers in low-income countries are small-scale, we examined and improved the performance of hand and knapsack-sprayers used locally in Tanzania. METHODS: We studied three salt facilities on the Bagamoyo coast, investigating procedures for preparing potassium-iodate solution, salt spraying and mixing. Different concentrations of solution were prepared and tested using different iodation methods, with the aim of attaining correct and homogeneous iodine levels under real-life conditions. Levels achieved by manual mixing were compared to those achieved by machine mixing. RESULTS: The overall median iodation level in samples of salt iodated using previously existing methods was 10.6 ppm (range 1.1 - 110.0 ppm), with much higher levels in the top than the bottom layers of the salt bags, p < 0.0001. Experimentation using knapsack-sprayers and manual mixing led to the reliable achievement of levels (60.9 ppm +/- 7.4) that fell within the recommended range of 40 - 80 ppm. The improved methods yielded homogenous iodine concentrations in all layers of salt-bags (p = 0.58) with 96% of the samples (n = 45) falling within 40 - 80 ppm compared to only 9% (n = 45) before the experiment and training (p < 0.0001). For knapsack-spraying, a machine mixer improved the iodine levels and homogeneity slightly compared to manual mixing (p = 0.05). CONCLUSION: Supervised, standardized salt iodation procedures adapted to local circumstances can yield homogeneous iodine levels within the required range, overcoming a major obstacle to universal salt iodation.
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- Assey, Vincent D., et al.
(författare)
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Iodine deficiency persists in the Zanzibar Islands of Tanzania
- 2006
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Ingår i: Food and Nutrition Bulletin. - : SAGE Publications. - 0379-5721 .- 1564-8265. ; 27:4, s. 292-299
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Tidskriftsartikel (refereegranskat)abstract
- Background. Iodine is an essential micronutrient for normal human growth and development. It is estimated that more than 1.6 billion people live in iodine-deficient environments, yet there are still some countries and areas where the prevalence of iodine-deficiency disorders is unknown. Objective. To establish the prevalence of iodine-deficiency disorders in the Zanzibar Islands, a community assumed to have ready access to iodine-rich seafoods. Methods. In a cross-sectional study, 11, 967 schoolchildren were Palpated for goiter prevalence, a subsample was evaluated for urinary iodine concentration, and the availability of iodated salt was assessed at the household and retail levels. Results. The mean total goiter prevalence was 21.3% for Unguja and 32.0% for Pemba. The overall median urinary iodine concentration was 127.5 ug/L. For Unguja the median was 185.7 mu g/L, a higher value than the median of 53.4 mu g/L for Pemba (p <.01). The household availability of iodated salt was 63.5% in Unguja and 1.0% in Pemba. The community was not aware of the iodine-deficiency problem and had never heard of iodated salt. Conclusions. The inadequate intake of iodine documented in the Zanzibar Islands belies the common assumption that an island population with access to seafood is not at risk for iodine-deficiency disorders. We urge health planners to implement mandatory salt iodation and education efforts to alleviate the situation.
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- Assey, Vincent D., et al.
(författare)
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Remaining challenges in Tanzania's efforts to eliminate iodine deficiency
- 2007
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Ingår i: Public Health Nutrition. - 1368-9800 .- 1475-2727. ; 10:10, s. 1032-1038
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To determine iodine levels in salt and iodine deficiency prevalence in school-aged children in 16 districts in Tanzania with previous severe iodine deficiency. Design: A cross-sectional study in schoolchildren. Systematic probability sampling was used to select schools and subjects for goitre assessment and urinary iodine determination. Setting: Sixteen districts randomly selected from the 27 categorised as severely iodine-deficient in Tanzania. Subjects: The stndy population was primary-school children aged 6-18 years who were examined for goitre prevalence and urinary, iodine concentration (UIC). Salt samples from schoolchildren's homes and from shops were tested for iodine content. Results. The study revealed that 83.3% of households (n = 21 160) in the surveyed districts used iodised salt. Also, 94% of sampled shops (n = 397) sold iodised salt, with a median iodine level of 37.0 ppm (range 4.2-240 ppm). Median UIC in 2089 schoolchildren vas 235.0 mu g 1(-1) and 9.3% had UIC values below 50 mu g 1(-1). The overall unweighted mean visible and total goitre prevalence was 6.7% and 24.3%, respectively (n = 16 222). The age group 6-12 Nears had the lowest goitre prevalence (3.6% visible and 18.0% total goitre, 11 = 7147). The total goitre prevalence had decreased significantly in all districts from an unweighted mean of 65.4% in the 1980s to 24.3% in 1999 (P < 0.05). We believe this difference was also biologically significant. Conclusion: These findings indicate that iodine deficiency is largely eliminated in the 16 districts categorised as severely iodine-deficient in Tanzania, and that the iodine content of salt purchased from shops is highly variable.
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- Assey, V. D., et al.
(författare)
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Sustainable universal salt iodization in low-income countries : time to re-think strategies?
- 2008
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 0954-3007 .- 1476-5640. ; 62:2, s. 292-294
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Sustained iodine deficiency control requires sustainable mechanisms for iodine supplementation. We aim to describe the status of salt iodation machines, salt producers' experiences and quality of salt produced in Tanzania. Methods: Qualitative and quantitative data was collected from the factory sites, observations were made on the status of UNICEF-supplied assisted-iodation machines and convenience samples of salt from 85 salt production facilities were analysed for iodine content. Results: A total of 140 salt works visited had received 72 salt iodation machines in 1990s, but had largely abandoned them due to high running and maintenance costs. Locally devised simple technology was instead being used to iodate salt. High variability of salt iodine content was found and only 7% of samples fell within the required iodation range. Conclusion: Although iodine content at factory level is highly variable, overall iodine supply to the population has been deemed largely sufficient. The need for perpetual iodine fortification requires reassessment of salt iodation techniques and production-monitoring systems to ensure sustainability. The emerging local technologies need evaluation as alternative approaches for sustaining universal salt iodation in low-income countries with many small-scale salt producers.
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- Assey, Vincent D, et al.
(författare)
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Tanzania national survey on iodine deficiency : impact after twelve years of salt iodation.
- 2009
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 55, s. 295-295
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In many low-income countries, children are at high risk of iodine deficiency disorders, including brain damage. In the early 1990s, Tanzania, a country that previously suffered from moderate to severe iodine deficiency, adopted universal salt iodation (USI) as an intervention strategy, but its impact remained unknown. METHODS: We report on the first national survey in mainland Tanzania, conducted in 2004 to assess the extent to which iodated salt was used and its apparent impact on the total goitre prevalence (TGP) and urinary iodine concentrations (UIC) among the schoolchildren after USI was initiated. In 2004, a cross-sectional goitre survey was conducted; covering 140,758 schoolchildren aged 6 - 18 years were graded for goitre according to new WHO goitre classification system. Comparisons were made with district surveys conducted throughout most of the country during the 1980s and 90s. 131,941 salt samples from households were tested for iodine using rapid field test kits. UIC was determined spectrophotometrically using the ammonium persulfate digestion method in 4523 sub-sampled children. RESULTS: 83.6% (95% CI: 83.4 - 83.8) of salt samples tested positive for iodine. Whereas the TGP was about 25% on average in the earlier surveys, it was 6.9% (95%CI: 6.8-7.0) in 2004. The TGP for the younger children, 6-9 years old, was 4.2% (95%CI: 4.0-4.4), n = 41,965. In the 27 goitre-endemic districts, TGP decreased from 61% (1980s) to 12.3% (2004). The median UIC was 204 (95% CF: 192-215) microg/L. Only 25% of children had UIC <100 microg/L and 35% were > or = 300 microg/L, indicating low and excess iodine intake, respectively. CONCLUSION: Our study demonstrates a marked improvement in iodine nutrition in Tanzania, twelve years after the initiation of salt iodation programme. The challenge in sustaining IDD elimination in Tanzania is now two-fold: to better reach the areas with low coverage of iodated salt, and to reduce iodine intake in areas where it is excessive. Particular attention is needed in improving quality control at production level and perhaps the national salt iodation regulations may need to be reviewed.
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- Chopra, Mickey, 1967-
(författare)
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Prevention of Mother to Child Transmission of HIV in Africa : Operational Research to Reduce Post-natal Transmission and Infant Mortality
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis assesses the effectiveness of the National Prevention of Mother to Child Transmission of HIV (PMTCT) programme in 3 sites in South Africa, and the quality of infant feeding counselling across four countries, Botswana, Kenya, Malawi and Uganda . Implementation and outcome of PMTCT services were very different across the 3 sites. The Paarl site is achieving results comparable to clinical trial studies with a HIV-free survival rate of 85% at 36 weeks, while Umlazi is somewhat lower (74%) and Rietvlei, with HIV-free survival of 64%. Maternal viral load, prematurity and site were independent risk factors for infection and/or death. The regression analysis suggests that some of this difference is explained by the differences in quality of health systems across the sites. Traditional risk factors (e.g. viral load, prematurity) do not seem to explain the substantial differences in HIV-free survival between the Paarl and Rietvlei sites.The overall mortality rate for HIV exposed infants in this cohort was 155 per 1000 live births at 36 weeks, a level higher than most other HIV exposed cohorts. The excess mortality is occurring almost completely amongst HIV infected infants who had a nine fold increased risk of mortality compared with HIV exposed but HIV negative infants. There was no significant difference in 36 week survival rates between those HIV exposed but uninfected infants and those who were not HIV exposed, Hazard ratio 0.7 (95% CI 0.3-1.5).With respect to HIV and infant feeding most health workers across the four countries (234/334, 70%) were unable to correctly estimate the transmission risks of breastfeeding. Exposure to PMTCT training made little difference to this. Infant feeding options were mentioned in 307 out of 640 (48%) observations of PMTCT counselling session and in only 35 (5.5%) were infant feeding issues discussed in any depth; of these 19 (54.3%) were rated as poor. South Africa was similar with only two out of thirty four HIV positive mothers being asked about essential conditions for safe formula feeding before a decision was made. This body of work has demonstrated that the gap between efficacy and effectiveness can be significant.
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