Evaluation of the iodine deficiency disorders control program in Lesotho

[摘要] The broad range of disorders in a population caused by an inadequate dietary supply of iodinewas denoted as iodine deficiency disorders (JDD), which include endemic goitre,hypothyroidism, cretinism and congenital anomalies. When iodine deficiency is widespread,mental retardation impedes national human resource development. Despite the knowneffective control measures, 130 WHO member states have a significant JDD problem. Severeto mild JDD have been reported in Lesotho since 1960.The most cost-effective and sustainable intervention to eliminate JDD is the iodisation of alledible salt. However, several countries with long standing salt iodisation programs havereported declining levels of urinary iodine. In Lesotho, the legislation on universal saltiodisation was promulgated in 2000. Therefore the aim of the study was to evaluate the saltiodisation program in Lesotho in terms of process, impact and sustainability indicators. A 30 cluster national survey was conducted where the proportion to population size methodwas administered. In each cluster, 30 women aged 15 to 30 years, and 30 primary schoolchildren aged 8 to 12 years, were randomly selected. The selected women and children werepalpated and thyroid size graded according to WHOIUNICEFIICCJDD (2001) criteria andurine samples collected. 30 salt samples were collected from these selected women, 6 samplesfrom 2 randomly selected retailers in each cluster, and 107 samples collected from all thecommercial entry points in the country. The salt samples were analysed using the iodometrictitration method while urine samples were analysed using the method using ammoniumpersulfate according to WHOIUNICEFIICCJDD (2001) recommendations. This analysis wasperformed at the Medical Research Council in Cape Town (South Africa) where theCoefficient of Variation for urinary iodine analysis was 7.7 at a concentration of IOug/l, andwas 2.7 at a concentration of 70ppm for titration method of salt analysis. The statisticalanalysis was done using the SAS program at the University of the Free State (South Africa).A total of927 children and 930 women who were palpated, and 912 children and 924 womenwho gave urine samples, were included in the analysis of the results. 930 salt samples from household level, 186 from retail level and 107 from entry point level were analysed. 3 saltsamples from entry point, 18 and 6 data sheets for urinary iodine of women and childrenrespectively were not included during statistical analysis. The median iodine concentration ofsalt was 36.2ppm (ranging from 30.5-55.4ppm in the different entry points), 37.3ppm (rangingfrom 12.4-50.2ppm in the different districts) and 38.5ppm (ranging from 29.2-43.2ppm in thedifferent districts) at entry point, retail level and household level respectively. At householdlevel only 1.6 percent used non iodised salt and 86.9 percent used adequately iodised salt. The analysis of the urine samples showed that the median urinary excretion was 214.7flg/1(ranging from 62.9flg/1 to 302.6flg/l in the different districts) for the children and 280.1flg/(ranging from 124.8flg/1 to 381.6flg/l in the different districts) for the women, indicating morethan adequate iodine intake according to the WHOIUNICEFIICCIDD (2001) report. Themedian iodine concentration was higher in boys (219.3flg/l) than in girls (212.6flg/I), higher inthe Lowlands (256.0 flg/l in children and 329.9 ug/l in women) than in the Mountains(99.30flg/l for children and 182.6flg/1 in women) and higher in non-pregnant women (283.0ug/l) than in pregnant women (212.1 ug/l). In the whole country, the prevalence of goitre was10.7 percent (ranging from 6.6% to 22.6 % in the different district) in children and 19.4percent (ranging from 6.7% to 36.7% in the different districts) in women, which indicatesmild IDD (WHOIUNICEFIICCIDD, 2001). IDD were observed more in females (14.0%)than in males (7.0%) and was less (4.3%) in children aged 8 than in children aged 12 years(12.9%). In women IDD increased with age from the age group of 15 to 19 (17.3%) to the agegroup of 20 to 25 (22 %) and decreased in the age group of 26 to 30 (18.4%). Similar tourinary iodine results, IDD was observed more in the Mountains (17.7% for women and18.1% for children) than in the Lowlands (14.3% for women and 6.7% for children). Only the urinary iodine excretion reached the WHOIUNICEFIICCIDD (2001) sustainabilitygoals. At household level, 86.9 percent of the households, which is slightly lower than therecommendation of at least 90 percent, use adequately iodised salt. Out of 10 programmaticindicators of sustainability, only 4 indicators have been attained by the salt iodisation programin Lesotho. According to the WHOIUNICEFIICCIDD (2001) at least 8 of the programmaticindicators should be attained for sustainable elimination ofIDD. The study demonstrates a major achievement in the household use of iodised salt andadequately iodised salt. However, salt is not iodised according to the legislation on universalsalt iodisation in Lesotho due to under iodisation and non- uniformity of salt iodisation at theproduction site. Iodine deficiency has been eliminated as a public health problem in Lesothoand this is due to the introduction of the legislation on universal salt iodisation. This studyhighlighted the effectiveness of iodised salt in increasing urinary iodine concentration.Iodine deficiency increased with age and was higher in girls than in boys, and higher in theMountains than in the Lowlands. IDD elimination in Lesotho will be sustainable if more than90 percent of the households use adequately iodised salt and the programmatic indicators suchas commitment to reassessment, political commitment, implementation of social mobilizationprogram and reqular monitoring are achieved by the IDD control task force. The administrative structure and activities of the IDD control task force need to be revised andstrengthened for the sustainable elimination ofIDD. The terms of reference of the committeeshould be revised, budgets for the activities be drawn, new members added and trained andresponsibilities given to each member. Awareness campaigns, which will start at policymakers' level, should be initiated. Law enforcement should be an integral part of the saltiodisation program. Effective regular monitoring of salt iodine content at all levels withspecial attention to iodisation of coarse salt is recommended together with periodic evaluationof the iodisation program.

[发布机构] University of the Free State