PHN06: Iodine Deficiency Disorders: Interventions that Worked, Lessons Learnt

Transcription

1 PHN06: Iodine Deficiency Disorders: Interventions that Worked, Lessons Learnt Objectives The last years have seen a worldwide effort to reduce the massive number of people suffering from iodine deficiency disorders. These disorders, resulting from a diet containing insufficient iodine, are especially during early pregnancy as they retard fetal development, particularly the development of the brain, resulting in a broad spectrum of intellectual, motor and. The deficiency of iodine is the single greatest cause of preventable mental retardation, a problem that may be easily prevented through iodizing salt for human and animal consumption. The objectives of this chapter include: Describing successful interventions for prevention of iodine deficiency disorders Discussing the lessons learnt from these efforts 1. Introduction In the past few years, global iodine nutrition has improved considerably, with the number of. However, statistics still indicate that 1.88 billion people around the world have an insufficient iodine intake, of which 241 million are children [1]. Iodine deficiency manifests in a number of ways. The spectrum of health consequences resulting from inadequate intake of iodine is collectively termed iodine deficiency disorders (IDD). This includes goiter, cretinism, impaired growth, impaired cognitive function, low birth weight and stillbirth. Iodine deficiency is the single most preventable cause for neurological and intellectual impairment. iodine deficiency disorders disorders occur in infants and children through maternal iodine deficiency. Extreme iodine deficiency during pregnancy may result in stillbirth, spontaneous abortion and cretinism, an irreversible form of mental retardation. The most common indicators of IDD include Enlarged thyroid gland: prevalence of goiter or total goiter rate (TGR) Urinary iodine excretion Elevated levels of thyroid stimulating hormones (TSH) in neonates at the time of birth Iodine deficiency is when over % of the children in 6-12 years is affected. Table 1 shows the indicators for Prevalence of IDD as a Public Health Problem. 1

2 Table 1: Indicators for Prevalence of IDD as a Public Health Problem Indicator Normal Mild IDD Moderate IDD Severe IDD % Goiter in school children < > 30 % Thyroid volume in school children < > 30 > 97 th percentile Median urine iodine (μg/l) < 20 % Neonatal thyroid stimulating hormone (TSH) >5 μiu/ml blood < > 40 Source: Delange F (1999) 2. Iodine Deficiency Interventions Iodine deficiency mainly occurs because of inadequate amounts of iodine present in soil. It Strategic planning at the global, national, provincial and community level is vital to the success of intervention programmes for the elimination of iodine deficiency. The planning process should incorporate key change agents and be adaptable to the situation they will be introduced into. Its key elements include: Assessment Advocacy Interventions Communications Evaluation Each of these elements should be closely linked, and empowered by able management and ongoing applied research and development. Although various intervention strategies exist such as iodization of water and bio- fortification the most commonly practiced intervention is salt fortification 2.1 Salt Fortification Iodization of salt remains the most commonly applied practice for the correction of iodine deficiency, involving the addition of suitable amounts of potassium iodate to salt meant for human and livestock consumption. The concept of fortifying salt with iodine may be associated with the French chemist, Boussingault, in the beginning of the 19th century. Since then, salt iodization has become the most popular means of combating iodine deficiency across the globe. Salt was chosen because it is widely available and universally consumed regularly on a daily basis, regardless of socioeconomic status. There is no effect on the colour, taste or consistency of salt on addition of iodine. Another important factor was that the cost of iodizing it was extremely low. 2

3 Universal salt iodization has been adopted as a sustainable, long-term solution to the control and eventual elimination of IDD. Numerous studies have indicated the success of salt iodization in controlling iodine deficiency. With introduction of salt iodization in 1922, the prevalence of IDD dropped dramatically. Since then, iodized salt has been providing sufficient iodine to ensure adequate iodine status to the entire Swiss population [3]. Apart from salt, which seems the most ideal means to deliver iodine, other foods have been fortified with iodine to meet this micronutrient requirement in iodine-deficient populations. These include tea in Tibet, water supplies in parts of Asia and Africa, fish paste in Thailand and bread in Australia Ten Years of Iodized Salt Intervention in Bangladesh According to the WHO Global Database on Iodine Deficiency, 2005, 2.5 billion people across the globe have insufficient iodine intake. Of these, 313 million are in Southeast Asia, including Bangladesh [5]. In 1989, all salt was to be compulsorily iodized, according to a law passed by the Government of Bangladesh. This entailed that salt must contain parts per million (ppm) of iodine at production, with no less than 20ppm iodine at the stage of retail, in order to ensure 15ppm of iodine at household level. In accordance to this, a plan was formulated for Universal Salt Iodization in the country. However, salt iodization met with slow progress until the publication of results of the first National IDD Survey in 1993, which recorded a very high prevalence of total goiter (47.1%), visible goiter (8.8%), cretinism (0.5%), and biochemical iodine deficiency (68.9%), indicated through a low urinary iodine excretion (<100μg/L) [6][7]. On basis of these findings, the Salt Bye-Law was passed in Large investments were made towards infrastructure for salt iodization. By the beginning of 1995, with the assistance of UNICEF, all 267 registered factories salt factories in Bangladesh were well equipped with Salt Iodization Plants (SIP), making iodized salt available all through the country. Two surveys assessing the progress towards achieving USI were undertaken, once in 1996 and the other in The first survey revealed that from 1996 to 1999, there was 54-55% of adequately iodized salt at household level. The first follow-up National IDD Survey in 1999 measured progress in eliminating IDD, and revealed a substantial decrease in IDD through the increased consumption of iodized salt. Thus, from 1993 to 1999, the goiter rate among the population had reduced from 47.1% to 17%, and biochemical deficiency had fallen from 68.9% to 43.1% [8]. The National IDD and USI Survey were repeated in 2005, to assess the latest situation. In the 2005 survey, data was collected from a random sample of households in Bangladesh between September 2004 and March It followed a stratified multistage cluster sampling design in order to provide nationally representative data, with rural-urban disaggregation. The survey population comprised 7233 children aged 6-12 years and 6408 women between 15 to 44 years of age. Physicians, using physical observation and palpation, examined this population for thyroid enlargement, and graded goiter according to the criteria recommended by the Joint WHO/UNICEF/ICCIDD Technical Consultation Group. Information about households was obtained using questionnaires, while samples of the salt used for cooking in households were analyzed as well urine samples from the population group were collected and analyzed for iodine. 3

4 The results indicated a total goiter rate of 6.2% in children compared to 49.9% in 1993 and 11.7% among women as compared to the earlier 55.6%. The prevalence of iodine deficiency also reduced from 71% in children and 70.2% in women in 1993 to 33.8% in children and 38.6% in women in 2005 [8]. The iodine nutrition status was found to be better in urban areas, mainly because of better availability and higher consumption of 'packet' salt in urban than rural areas. A clear inverse relationship was also found to exist between iodine deficiency and use of iodized salt. The survey concluded that Bangladesh has benefited immensely from the universal salt iodization programme that was instituted a decade ago. However, physiological iodine deficiency still exists among over one-third of women and children, which serves as an indicator that added efforts are required for achieving universal salt iodization National Iodine Deficiency Disorders Elimination Programme, China, 1993 China is vastly affected by iodine deficiency, bearing the heaviest burden in the world. Studies in 1995 revealed that approximately 400 million people in China were estimated to be at risk of IDD, making up 40% of the global total. In 1993, in an effort to eliminate iodine deficiency, the Chinese government launched the National Iodine Deficiency Disorders Elimination Programme with assistance of the donor-funded Iodine Deficiency Disorders Control Project. During this time, there was limited awareness of the effects of iodine deficiency, especially in many regions in China that were at the highest risk, where goiter was considered normal. On the other hand, people living in salt-producing regions did not want to buy salt. These were certain challenges faced in the intervention for iodine deficiency in China. The nationwide public health campaign began with informing the public about the gravity of the deficiency and the need to buy only iodized salt. Newspaper editorials, posters on buses and television documentaries were used to inform people and to create a demand for iodized salt. Judicious interventions in the salt producing industry, enabled access to iodized salt all across the country. Pre-existing salt iodation factories were upgraded to increase production while 112 new iodation centres were established. New packaging technology was also adopted. By 1999, iodized salt had reached 94% of China, as compared to the earlier 80% in 1995 [9]. Substantial progress was made towards universal salt iodization by the end of 2000, wherein China was virtually free of iodine deficiency disorders. As a result of the programme, the quality of iodized salt also improved. The programme's impact on health has also been noteworthy. There was a dramatic reduction in iodine deficiency among schoolchildren, with much fewer children displaying signs of goiter across the country. The total goiter rate for children between 8 and 10 years of age fell from 20.4% in 1995 to 8.8% in Overall, the National Iodine Deficiency Disorders Elimination Programme was a huge success, offering valuable lessons for future public health campaigns National Iodine Deficiency Disorders Control Programme, India, 1962 India has been one of the foremost countries in the world to start a national IDD control programme. In India, this programme has evolved dynamically, becoming a success story from which to identify solutions for the future. Manifestations of iodine deficiency have been known for over 5,000 years now. Goiter finds mention in both Indian as well as Chinese scriptures. The Atharva Veda mentions 'Galanda' or swelling in the neck, and mentions it as treatable. As early as AD, goiter appears in the artwork depicting Buddha and his disciples. In more recent times, goiter was first documented in India as prevalent in the Gilgit and Chitral Valley of Kashmir, in 1905 by McCarrison [10]. 4

5 Using iodized salt as an intervention to address goiter was first initiated in Switzerland and USA in the 1920s. In India, the effectiveness of salt fortification for the control of IDD was established through the landmark study from in the Kangra Valley in Himachal Pradesh [11]. The success of this study paved the way for the establishment of the National Goiter Control Programme (NGCP) in India in The key strategy of the programme involved promoting the consumption of iodized salt in endemic areas for control of goiter. The programme was modified and renamed National Iodine Deficiency Disorders Control Programme (NIDDCP) in Important features of the NIDDCP: Surveys to assess magnitude of IDD Supply of iodized salt in place of common salt Re-survey after every five years to assess extent of IDD and the impact of iodized salt Laboratory monitoring of iodized salt and urinary iodine excretion Health education and publicity Goals of the NIDDCP according to the 11th Five-Year Plan of the Government of India: To reduce prevalence of IDD to below 10% in the country by 2012 To achieve universal access to iodized salt In 1986, the Government of India advised all states to make iodization of salt mandatory, for direct human consumption under provisions of the Prevention of Food Adulteration (PFA) Act 1954, in accordance with the advice of Central Committee for Food Standards. In 2011, regulations under the Food Safety and Standards Act, 2006, which has replaced the PFA Act 1954 were notified banning the sale of non-iodized salt for direct human consumption. Phases of IDD Control Programme in India (i) Phase 1: From research to policy ( ) The National Goiter Control Programme (NGCP) was established in 1962 following the success of the Kangra Valley study at the end of the second Five-Year Plan. The NGCP focused on endemic districts. Twelve salt iodization plants were established in this period, all in the public sector. Total salt production was estimated to be only 15% of the requirement. During this period, the NGCP had remained a low priority health programme due to its area specific approach and the fact that IDD was considered a mild cosmetic problem in the Himalayan regions only. (ii) Goiter to IDD ( ) Studies from India and around the globe shed new scientific evidence about iodine deficiency and the significance of impact of IDD on early brain development, cognition and learning abilities of children. The whole nation was shown to be endemic for IDD, with neonatal hypothyroidism being highly prevalent in certain parts of India [12]. This problem of deficiency cast a shadow on the achievement of the goal of "Education for All", and convinced political leadership of the critical nature of the problem, thereby also securing priority commitment. (iii) Lifting the ban on sale of non-iodized salt ( ) 5

6 In September 2000, the Government of India lifted the ban on sale of non-iodized salt for human consumption. This move caused a subsequent dip in the production of iodized salt to 4.1 million tons in 2003, and a reduction in the household coverage of iodized salt. (iv) Reinstatement of ban on sale of non-iodized salt and consolidation of sustainable elimination of IDD (Since 2005)[13,14]. In 2004, following sustained advocacy and mounting evidence, the Core Advisory Group on Public Health and Human Rights of National Human Rights Commission was requested to critically examine the public health consequence of lifting ban on mandatory salt iodization. In keeping with the recommendation by the Core Advisory Group, the ban on sale of non-iodized salt was reinstated in According to the Coverage Evaluation Survey 2009, 71% households were consuming adequately iodized salt, and another 20% were consuming salt with some iodine [15]. The production of iodized salt also increased to 6.2 million tons in The IDD control programme in India has been a success story, closing the gap between efforts and the target of greater than 90% household level coverage of adequately iodized salt of USI. The successful evolution of the IDD control programme provides valuable insight and lessons for the successful and sustainable implementation of similar health programmes in other regions in the world Persistence of Iodine Deficiency in Certain Areas in India While the IDD control programme in India has been largely successful, there are certain areas where USI is yet to be successful. Results for a study conducted in 24 districts in West Bengal revealed a combination of high goiter prevalence, and normal median urinary excretion [16]. This was indicative of the fact that these districts were in transition from iodine deficient to iodine sufficient state. The persistence of non-iodized salt consumption indicates that the universal salt iodization programme needs to be intensified. In another study to determine the impact of USI on the prevalence of iodine deficiency in an iodine deficiency area in northern India, it was found that though there was an overall improvement in iodine nutrition, as observed through decreased goiter prevalence and increased median urinary iodine levels. The major causes of IDD in these regions include: Poor coverage Use of unpackaged crystal salt with inadequate iodine Washing of salt before use The Goiter and Cretinism Eradication Project (GCEP), Nepal The GCEP was established in 1978 under the Expanded Immunization Programme of the Ministry of Health, Nepal. In this intervention, iodized oil injections were administered to people in 40 districts located in hill and mountain belts, every five years between 1983 and In 1993, the GCEP was integrated within the Nutrition Section of the Child Health Division, Department of Health Services in the Ministry of Health. Following this, iodine capsules were administered orally, delivered through the existing network of the Primary Health Care system including mobile Village Health Workers. The number of districts initially targeted reduced significantly in number through improvement in infrastructure, thereby allowing areas previously difficult to reach by road, access to iodized salt Iodination of Irrigation Water in Xinjiang, China,

7 After the failure of the salt iodization programme in southern Xinjiang, China, irrigation water was iodinated, in order to increase the iodine content in soil, crops, animals and human beings. A 5% potassium iodate solution was dripped into irrigation canals for either twelve or twenty-four days, to reach rural populations. The soil iodine remained stable over one winter, and following dripping of iodine in the second year, resulted in a 4-fold increase in soil iodine and a 1.8-fold increase in iodine in crops [27][28]. Iodine added to the soil in this way was found available for more than four years after a single application. Iodination of irrigation water was found to be an advantageous way of supplying iodine, one that could be carried out in other irrigation-dependent areas as well. It was also cost-effective, with the added benefit of improving livestock production. It was concluded that potassium iodate added to the soil appears to increase soluble iodine out of proportion to the amount added. To maximize the benefits of this intervention, it is recommended that agricultural practices, which enhance retention of soil iodine, be considered. Also, the factors that strongly fix iodine in the soil, thereby making iodine unavailable for uptake by plants, should be restricted. Such methods would include the addition of organic matter such as straw and manure to the soil, to retain iodine. It is also recommended that the long-term fate of soil iodine added by irrigation programmes be investigated more thoroughly Iodine Dripping Programme in Inner Mongolia The Inner Mongolia Centre for Endemic Diseases Prevention began a project involving iodination of irrigation water in 2002, similar to the one undertaken in the Xinjiang District in China. An additional feature in this programme was the measurement of total soil iodine in addition to the soluble iodine, in order to assess the fate of the iodate added to the soil. Potassium iodate was added in two townships, namely Nalinxili and Holosumu in Yijinholo country in central Mongolia. The soil and agricultural conditions were very similar to that in Xinjiang, China. After dripping potassium iodate, the indices were followed for four years. The results at the end of this time period were parallel to those found in Xinjiang [29]. The soluble iodine and total soil iodine were found to rise, and remain elevated for four years, with only a modest fall-off in that time. Iodine uptake by plants and poultry and animals was found to increase, and thus poultry and animal products contained iodine as well. This persisted for at least four years. Urinary iodine in human population groups was found to largely increase, and persist that way for four years. Before the dripping with potassium iodate, the population had been treated with oral iodized oil capsules because of which the urine iodine values were not low before the dripping, with the exception of nursing mothers. However, the oral capsules were discontinued after the start of dripping. The later values thereby represent the effect of dripping [30]. The results of the Iodine Dripping Programme in Inner Mongolia confirm the permanence of dripped potassium iodate for over four years in the desert soils of central Asia, thereby confirming this method of intervention as available for humans. Another benefit of this method was the improvement in livestock production and quality, bestowing an economic benefit as well. 3. Lessons Learned through Iodine Interventions Experience gleaned from over eight decades in implementing salt iodization programmes has provided a number of valuable lessons on how to achieve and sustain progress. These may be summarized into the following guiding principles 7

8 (i) Secure Political Commitment A combination of public policies, private sector dedication and civic commitment has resulted in the global success of salt iodization programmes. Of these, a strong, continuous government commitment and industry motivation remain paramount to continued efforts in eliminating IDD. This commitment requires regular advocacy in order to be maintained and strengthened. (ii) Form Partnerships and Coalitions Programmes of such magnitude require effective partnerships at all levels of operation and administration. These include partnerships between governments and salt producers, government and donors, between salt producers and traders, and among all the groups involved in supporting elimination efforts. These ties need to be strengthened at all levels. National and sub-national coalitions with clearly defined roles and responsibilities can provide a driving force in promoting collaboration. (iii) Ensure Availability of Adequately Iodized Salt When iodization is made mandatory, it will ensure universal access. The salt industry should treat iodization as its fundamental responsibility, while governments should collaborate with salt producers to help them improve their capacity, and producers should maintain this capacity. This will necessitate the close working and involvement of governments with manufacturers, small enterprises and traders. The government may also need to disburse revolving funds to keep the supply of iodized salt consistent. Marketing and sales should ensure that the iodized salt reaches socially and geographically isolated communities. (iv) Strengthen Monitoring and Surveillance Systems For the success of IDD intervention programmes, a continuous and effective monitoring system is required. This includes Covering salt iodine content, right from the point of production to the point of consumption Covering impact, to determine iodine nutrition status of consumers Covering overall programme sustainability, including elements such as legal mandated salt iodization, health education regarding iodine in schools etc. The results of these monitoring systems should be linked to information on iodine nutrition status, and should include efficient systems that convey these results to the concerned decision makers for their use. Results should also be shared with the general public. (v) Maintain Continuous Education and Communication Creating awareness about IDD and its consequences is an important factor in the success of iodine intervention programmes. Communication efforts should include specific messages tailored to various audiences including national leaders, the salt industry, technical and professional groups, teachers and families. These messages should be delivered via every possibly type of media, right from television to a person-to-person dissemination of information. Communication must be regular and ongoing. It should also articulate concrete accountabilities. 8

9 These guiding principles have underscored the actions responsible for raising the percentage of households consuming iodized salt from less than 20%, two decades back, to 70% in the present day. These lessons learned from iodine intervention programmes, when applied to future programmes, could help in the total elimination if IDD, through relentless, continued efforts [30]. 4. Summary Iodine deficiency leads to a range of health and developmental consequences termed Iodine Deficiency Disorders. It is especially damaging during early pregnancy and in early childhood, affecting brain development. In its most severe forms, IDD can lead to cretinism, stillbirth and miscarriage. Even a mild deficiency can interfere with learning abilities. Iodine deficiency is the single, greatest cause of preventable mental retardation across the globe. IID problem, however, may be easily prevented through the consumption of iodized salt. Although there has been considerable success in the universal salt iodization programme during the last two decades, there is still a long way to go before we can achieve the target goal, of consumption of adequately iodized salt in over 90% of the households. 9