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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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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