A prevalence study of vitamin A deficiency and xerophthalmia in northeastern Thailand

Xerophthalmia and Its Associated Factors among School-Age Children in Amba Giorgis Town, Northwest Ethiopia, 2018

INTRODUCTION

Xerophthalmia is a general term applied to all the ocular manifestations from night blindness through complete corneal destruction (keratomalacia) due to vitamin A deficiency. Xerophthalmia is the main contributing factors for childhood blindness in developing countries. However, there is limited evidence that can implicate the current situation. This study aimed to determine the magnitude of xerophthalmia and associated factors among school-age children in Northwest Ethiopia.

METHODS

A community-based cross-sectional study was conducted on 490 children, age range of 6 to 12 years. The study participants were selected through systematic random sampling method. Data were collected using a pretested structured questionnaire and ophthalmic examination with different ophthalmic instruments. The analyzed result was summarized and presented using descriptive statistics. Binary logistic regression was used to determine the factors associated with xerophthalmia. Variables with a p value of <0.05 in the multivariable logistic regression analysis were considered as statistically significant.

RESULTS

A total of 484 study participants with a response rate of 98.8 were involved in this study, and their median age was 8 years with IQR of 4 years. The prevalence of xerophthalmia was 8.26% (95% CI: 5.8, 10.7). Family income less than 1000 Ethiopian birr (AOR = 4.65, 95% CI: 1.31, 16.4), presence of febrile illness (AOR = 2.8, 95% CI: 1.49, 6.11), poor consumption of fruits and vegetables (AOR = 3.18, 95% CI: 1.30, 7.80), and nonimmunized status (AOR = 3.43, 95% CI: 1.49, 7.89) were significantly associated with xerophthalmia.

CONCLUSIONS AND RECOMMENDATIONS

The prevalence of xerophthalmia was high as compared to the World Health Organization criteria for public health significance. Factors identified for xerophthalmia in this study are low income, the poor dietary practice of fruits and vegetables, and the presence of febrile illness and not immunized. Hence, it is a public problem that needs attention.

Moving a Health System from a Medical towards a Dietary Approach in Thailand

Amidst the picture of subclinical vitamin A deficiency in north and north-east Thailand, hospital records revealed 31 cases of infant xerophthalmia in the lower southern region in 1991. Major risk factors included inadequate breastfeeding, consumption of non-fortified sweetened condensed milk, and the presence of pneumonia, diarrhoea, or both. A survey conducted jointly by the Ministry of Public Health (MOPH) and the Institute of Nutrition, Mahidol University (INMU), indicated a public health problem of vitamin A deficiency in pre-school children. A partnership relationship was established between MOPH as an implementation agency and INMU in the technical support role towards alleviating vitamin A deficiency in the lower southern provinces. Intervention began with distribution of high-dose vitamin A capsules in the high-risk areas, followed by fortification of sweetened condensed milk with vitamin A (330 retinol equivalents/100 g). At the same time, a dietary diversification strategy was planned to promote consumption of vitamin A–rich foods in the local menus or fish chips enriched with chicken or beef liver. No new cases of xerophthalmia have been reported since 1995. Periodic subsample surveys indicated that the severity of the problem has declined to a subclinical stage. Key elements of progress include partnership between MOPH and INMU from planning to implementation, transition of MOPH to a more preventive and promotive approach, continuous communication from top to grass-roots-level officers, and coupling of research with programmes.

Retinoic acid modulates hepatic iron homeostasis in rats by attenuating the RNA-binding activity of iron regulatory proteins

Vitamin A deficiency has been widely associated with perturbations of iron homeostasis, a consequence that can be reversed by retinoid supplementation. Despite the numerous studies that demonstrate an interaction between these 2 nutrients, the mechanistic basis for this relation has not been well characterized. Because iron regulatory proteins (IRP) have been established as central regulators of iron homeostasis, we investigated the potential role of IRP in the regulation of iron homeostasis under conditions of vitamin A deficiency and supplementation with all-trans-retinoic acid (atRA). Rats were fed a control diet or a diet deficient in either vitamin A or iron or both micronutrients. Four parallel groups of rats were supplemented with atRA daily (30 micromol/kg body weight) during the final week of this study. As expected, iron-deficient (-Fe) rats exhibited a decrease in hepatic nonheme iron levels and a subsequent increase in IRP RNA-binding activity, resulting in diminished ferritin abundance. Interestingly, atRA supplementation inhibited the increase in IRP RNA-binding activity in -Fe rats to a level that was not significantly (P = 0.139) different from control values, and it partially restored ferritin abundance. This inhibition of IRP RNA-binding activity by atRA supplementation was also associated with a 40% reduction in transferrin receptor abundance. Taken together, these results indicate that IRP represent a mechanistic link between vitamin A and the regulation of iron homeostasis, a key finding toward further understanding this important nutrient-nutrient interaction.

Does zinc deficiency play a role in stunting among primary school children in NE Thailand?

Stunting in school-age years may result in a decrease in adult size, and thus reduced work capacity and adverse reproductive outcomes. We have compared the mean intakes of energy, protein and selected growth-limiting nutrients in fifty-eight stunted children and 172 non-stunted controls drawn from 567 children aged 6–13 years attending ten rural schools in NE Thailand. Control children were selected randomly after stratifying children by age in each school. Dietary data were calculated from 24-h recalls using nutrient values from Thai food composition data and chemical analysis. Inter-relationships between stunting and sociodemographic, anthropometric and biochemical variables were also examined. Biochemical variables investigated were serum albumin, zinc, ferritin, transferrin receptor and retinol, and iodine in casual urine samples. Significantly more males than females were stunted (males, n 38, 65·5 % v. females, n 20, 34·5 %; P = 0·025). Stunted males had lower mean intakes of energy, protein, calcium, phosphorus and zinc, and a lower mean (95 % CI) serum zinc (9·19 (8·53, 9·84) v. 9·70 (8·53, 9·29) μmol/l) than non-stunted males; no other biochemical differences were noted. Stunted males also had a lower mean arm muscle area (P = 0·015), after adjusting for age, than non-stunted males. In conclusion, the lower dietary intakes of the stunted males compared to their non-stunted counterparts may be associated with anorexia and hypogeusia induced by zinc deficiency. Hence, zinc deficiency may be a factor limiting linear growth, especially among boys in NE Thailand, but more research is needed to establish whether other factors also play a role.

Clinical disorders affecting mesopic vision

Vision in the mesopic range is affected by a number of inherited and acquired clinical disorders. We review these conditions and summarize the historical background, describing the clinical characteristics alongside the genetic basis and molecular biological mechanisms giving rise to rod and cone dysfunction relevant to twilight vision. The current diagnostic gold standards for each disease are discussed and curative and symptomatic treatment strategies are summarized.

Risk of zinc, iodine and other micronutrient deficiencies among school children in North East Thailand

INTRODUCTION

Micronutrient deficiencies during childhood can contribute to impairments in growth, immune competence, and mental and physical development, and the coexistence of several such deficiencies can adversely affect the efficacy of single micronutrient interventions.

OBJECTIVE

To assess the prevalence of zinc and iodine deficiency and their interrelationships with vitamin A deficiency and anemia and associations with socio-economic status, hemoglobin type, and anthropometry in a cross-sectional study.

SETTING

A total of 10 primary schools in North East Thailand.

METHODS

Non-fasting venipuncture blood samples and casual urine samples were collected from 567 children aged 6-13 years. Anthropometric measures and serum zinc, albumin, C-reactive protein and urinary iodine, are reported here and integrated with published data on vitamin A, anemia, and socio-economic status.

RESULTS

Of the children, 57% had low serum zinc and 83% had urinary iodine levels below the 100 microg/l cutoff. Suboptimal serum zinc and urinary iodine concentrations may result from low intakes of zinc and iodized salt. Significant risk factors for low serum zinc were serum retinol <1.05 micromol/l and being male. Those for urinary iodine <100 microg/l were height-for-age score>median and being female. For serum retinol <1.05 micromol/l, risk factors were low hemoglobin, low serum zinc, and <9 years, and for low hemoglobin indicative of anemia risk factors were <9 years, AE hemoglobinopathy, and serum retinol <1.05 micromol/l. Of the children, 60% were at risk of two or more coexisting micronutrient deficiencies, most commonly suboptimal urinary iodine and low serum zinc.

CONCLUSION

The findings emphasize the need for multimicronutrient interventions in North East Thailand.

Hipovitaminose A em pré-escolares de creches públicas do Recife: indicadores bioquímico e dietético

OBJETIVO: Estimar a prevalência de hipovitaminose A em pré-escolares de creches públicas da cidade do Recife, Estado de Pernambuco, Brasil. MÉTODOS: Estudo de corte transversal, envolvendo 311 crianças menores de cinco anos, de ambos os sexos, aleatoriamente selecionadas, e avaliadas pelos indicadores bioquímico (retinol sérico), dietético (inquérito de consumo alimentar) e antropométrico (peso/idade, altura/idade e peso/altura). RESULTADOS: A prevalência de níveis de retinol sérico baixos (<0,70µmol/L) foi de 7,0%, caracterizando a deficiência de vitamina A como problema de saúde pública do tipo leve, segundo critérios da Organização Mundial de Saúde. Cerca de 78,0% das crianças apresentaram adequação do consumo de vitamina A, considerando-se as cifras recomendadas pela Dietary Reference Intakes, 2001. A distribuição dos níveis séricos de retinol e do consumo alimentar de vitamina A foi homogênea, segundo o sexo. No entanto, crianças na faixa etária de 12 a 48 meses mostraram menor consumo de alimentos fonte de vitamina A em relação às crianças das demais faixas etárias (p<0,05). A prevalência de baixo peso foi de 7,5%, de retardo do crescimento linear de 8,1% e de desnutrição aguda de 1,8%. A hipovitaminose A não mostrou correlação com a desnutrição energético-protéica (p>0,05). O consumo dietético de vitamina A mostrou sensibilidade reduzida (43,0%) e baixíssimo valor preditivo positivo (6,8%) no diagnóstico da hiporretinolemia. CONCLUSÃO: A identificação de grupos populacionais vulneráveis, bem como a seleção de indicadores fidedignos do estado nutricional de vitamina A, são elementos essenciais para o diagnóstico e o planejamento de ações visando à prevenção e ao controle dessa carência nutricional específica.

Vitamin A deficiency and xerophthalmia among school-aged children in Southeastern Asia

OBJECTIVE

To determine provisional estimates of the extent of vitamin A (VA) deficiency and xerophthalmia among school-aged children.

DESIGN

Literature search of published, unpublished and website-based population survey and study reports, with country-specific imputation of prevalence rates and numbers of children affected by: (1) VA deficiency based on measured or imputed distributions of serum retinol concentration < 0.70 micromol/l (equivalent to < 20 microg/dl) and (2) xerophthalmia, by country.

SETTING

Countries within the WHO South-East Asian Region.

SUBJECTS

The target group for estimation was children 5-15 y of age.

INTERVENTIONS

None.

RESULTS

The estimated prevalence of VA deficiency is 23.4%, suggesting that there are approximately 83 million VA-deficient school-aged children in the region, of whom 10.9% (9 million, at an overall prevalence of 2.6%) have mild xerophthalmia (night blindness or Bitot's spot). Potentially blinding corneal xerophthalmia appears to be negligible at this age.

CONCLUSIONS

VA deficiency, including mild xerophthalmia, appears to affect large numbers of school-aged children in South-East Asia. However, nationally representative data on the prevalence, risk factors and health consequences of VA deficiency among school-aged children are lacking within the region and globally, representing a future public health research priority.

Ocular manifestation of vitamin A deficiency among Orang asli (Aborigine) children in Malaysia

This study determined the prevalence of ocular manifestation of vitamin A deficiency in Orang Asli (Aborigine) children. Night blindness was found in 16.0% of the children, conjunctiva xerosis in 57.3%, Bitot's spot in 2.8%, corneal xerosis in 0.5% and corneal scars in 5.6%. These findings show that history of night blindness had sensitivity, specificity and predictive value (positive) of 47.2, 98.1 and 96.2%, respectively, compared with the standard diagnosis procedure using luxometer readings.

Iron deficiency and marginal vitamin A deficiency affect growth, hematological indices and the regulation of iron metabolism genes in rats

Iron deficiency and marginal vitamin A (VA) deficiency frequently coexist and affect billions of people, mostly children and women, worldwide. The effects of these micronutrient deficiencies alone and in combination on hematologic, biochemical and molecular indices of iron and VA status were investigated in a 2 x 2 randomized blocked study conducted in growing male Sprague-Dawley rats. From 3-8 wk of age, rats were fed one of four purified diets that were either adequate or restricted in iron (Fe) and adequate or marginal in VA: (+)Fe(+)VA, 20.3 and 0.367 micro g/g, respectively, denoted control diet; (-)Fe(+)VA, 3.34 and 0.405 micro g/g; (+)FeVA(m), 22.2 and 0.051 micro g/g; or (-)FeVA(m), 3.03 and 0.055 micro g/g. Weight-matched rats fed adequate micronutrients were included to control for possible confounding effects of Fe deficiency on growth and feed efficiency. Iron restriction reduced (P < 0.05) weight gain, feed efficiency, blood hemoglobin and hematocrit. Plasma and liver iron and plasma transferrin saturation were reduced by approximately 50%, whereas liver transferrin mRNA and protein and transferrin receptor mRNA were elevated, as was liver ferritin light-chain protein and light-chain mRNA. Liver heavy-chain ferritin mRNA, hemopexin, ceruloplasmin and cellular retinol-binding protein mRNA were not affected by iron or VA restriction. Although marginal VA deficiency did not exacerbate indices of poor iron status during iron deficiency, iron deficiency was associated with lower plasma retinol and elevated liver VA concentrations. These results are consistent with an impaired mobilization of liver retinol during iron deficiency as well as multiple alterations in iron metabolism.

Recommendations for indicators: night blindness during pregnancy--a simple tool to assess vitamin A deficiency in a population

Night blindness during pregnancy caused by vitamin A deficiency is associated with an increased risk of morbidity and mortality among women. Because a history of maternal night blindness is simple and reliable to use, it is recommended as a population-based indicator of vitamin A deficiency. Furthermore, a maternal night blindness prevalence of >/=5% is recommended as a cut-off at which vitamin A deficiency may be considered to be a problem of public health significance within the community. This paper provides the justification for these recommendations. Night blindness during pregnancy is strongly associated with low serum and breast milk vitamin A concentration, abnormal conjunctival impression cytology and impaired dark adaptation, which suggests that it is a valid indicator of vitamin A deficiency. The prevalence of night blindness during pregnancy tends to be high in countries where the prevalence of xerophthalmia in children is high and in countries where interventions are in place to reduce childhood vitamin A deficiency. Existing data suggest that misclassification of self-reported maternal night blindness may account for a prevalence of up to 3%. The suggested cut-off, 5%, is set higher than this potential level of false-positive prevalence (3%). Illustrative data from India and Cambodia on childhood xerophthalmia and maternal night blindness rates are used to demonstrate the validity of using a 5% prevalence of maternal night blindness as indicative of a community vitamin A deficiency problem. Finally, it is recommended that night blindness history be elicited for a previous pregnancy that ended in a live birth in the past 3 y, using the local term for night blindness whenever possible.

Dietary intake and nutritional status of young children in families practicing mixed home gardening in northeast Thailand

One current initiative to assist rural Thai families to increase home food production and security is the implementation of home gardens that produce fish, small animals, and vegetables. This paper presents the results of an investigation comparing seasonal dietary intake and nutritional status among northeastern Thai children in mixed-gardening and nongardening families (n = 30 for each group). Assignment to the gardening group was based on the presence of a mixed garden, whereas nongardening subjects were randomly selected and matched for comparison. Statistical analysis (paired t-test) indicated that there was no significant difference in the observed biochemical variables (serum retinol, ferritin, hemoglobin) between groups at the p < or = .05 level. Nutritional status in regard to height-for-weight, weight-for-age, and weight-for-height Z scores was better among children of gardening families, although the differences were not significant. The small sample size and reported results indicate that the relationship between the practice of mixed home gardening and dietary intake and nutritional status needs further investigation.

Exposure to N-nitroso compounds in a population of high liver cancer regions in Thailand: volatile nitrosamine (VNA) levels in Thai food

The recent case-control studies in Thailand indicate that a high incidence of liver cancer in Thailand has not been associated with common risk factors such as hepatitis B infection, aflatoxin intake and alcohol consumption. While the infestation by the liver fluke Opisthorchis viverrini (OV) accounted for the high risk in north-east Thailand, there was no such exposure in the other regions of the country where the incidence of liver cancer is also high. Case-control studies suggest that exposure to exogenous and possibly endogenous nitrosamines in food or tobacco in betel nut and cigarettes may play a role in the development of hepatocellular carcinoma (HCC), while OV infestation and chemical interaction of nitrosamines may also be aetiological factors in the development of cholangiocarcinoma (CCA). Over 1800 samples of fresh and preserved food were systematically collected and tested between 1988 and 1996. All the food items identified by anthropological studies to be consumed frequently in four major regions of Thailand were analysed for volatile nitrosamines using gas chromatography combined with a thermal energy analyser. Relatively high levels of N-nitrosodimethylamine (NDMA), N-nitrosopiperidine (NPIP) and N-nitrosopyrrolidine (NPYR) were detected in fermented fish ("Plasalid"). NDMA was also detected at levels ranging from trace amounts to 66.5 microg/kg in several salted and dried fish ("Larb-pla" and "Pla-siu"). NDMA and NPYR were frequently detected in several vegetables, particularly fermented beans ("Tau-chiau") at levels ranging between 1 and 95.1 microg/kg and 0-146 microg/kg, respectively. The possible role of nitrosamines in Thai food in the aetiology of liver cancer (HCC, CCA) is discussed.

Prevalência de hipovitaminose a em crianças da periferia do município de Campinas, São Paulo, Brasil

A prevalência de hipovitaminose A foi determinada pelos níveis séricos de retinol por cromatografia líquida de alta eficiência (Clae) em 131 crianças com idade entre 3 e 10 anos, residentes em 18 favelas do Município de Campinas, São Paulo, no período de abril de 1991 a fevereiro de 1992. A prevalência encontrada foi 17,6% com níveis entre 0,35 e 0,70 µmol/L (IC=11,1-24,1; 95%), o que indica a existência de certo risco de saúde pública. Entretanto, exames clínicos oftalmológicos não detectaram nenhum caso de xeroftalmia. Informações complementares sobre as características da amostra foram obtidas para 341 crianças. A renda per capita mostrou-se surpreendentemente alta. O consumo alimentar, segundo os critérios da FAO/WHO, só foi adequado para proteínas (133,96%), sendo os menores valores de adequação aqueles encontrados para energia (87,76%) e, principalmente, para vitamina A (66,13%) e ferro (42,14%). Os indicadores altura/idade e peso/altura identificaram muitas crianças abaixo de -1 desvio padrão.

A clinical and cytological study of vitamin A deficiency in Kiribati

Vitamin A status was assessed clinically and by conjunctival impression cytology in a selected group under seven years of age in the Republic of Kiribati. A total of 230 children were studied. Of 185 with readable histology, 14.6% were clinically and histologically abnormal; 19.5% were clinically abnormal but histologically normal; and 15.7% were clinically normal and histologically abnormal. The remainder (50.3%) were clinically and histologically normal. There was a significant correlation between clinical disease and histology (P < 0.001). The prevalence of the disease in males was 45.8% and 26.3% in females. The risk of deficiency appeared to increase with advancing age. There was no significant difference between the two villages studied.

Response of Bitot's spots in preschool children to vitamin A treatment

In a double-masked, placebo-controlled, clinical trial in Indonesia, 88 preschool children between the ages of 36 and 72 months with Bitot's spots were randomly assigned to 200,000 IU of oral vitamin A or placebo and followed up for five weeks. Baseline and follow-up serum vitamin A levels were obtained. Of the 45 children receiving vitamin A, 33 (73.3%) showed complete cure and disappearance of Bitot's spots, six (13.3%) had disappearance of some but not all Bitot's spots, and six (13.3%) were unresponsive to treatment. The nonresponsive children were older, all male, and had higher initial mean serum vitamin A levels, 23.0 micrograms/dl, compared to 15.9 micrograms/dl in the cured group (P = .017). These data suggest that normal vitamin A status may be found in approximately 13% of children with Bitot's spots before vitamin A intervention and that one fourth of those who had Bitot's spots originally will not be cured of all Bitot's spots after intervention. These are important factors to consider when using Bitot's spots in prevalence surveys as a clinical sign of vitamin A deficiency.