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南アジアにおける低栄養の気候変動インパクト

計画書

研究代表者
(所属)
我妻ゆき子(筑波大学 医学医療系)
研究関係者
(所属)
林 泰一(京都大学 防災研究所)、David Sack(The Johns Hopkins University) Md. Harunor Rahid (筑波大学 人間総合科学研究科)
研究期間 2014年7月~2015年3月
研究概要

 気候変動は今世紀最大のチャレンジ課題となっており、公衆衛生政策にもその重要性が年々高まっている。これまでの研究では、ある種の感染症や自然災害が増加することが言われている。しかし、多くの国ではそれらの被害を最小限にする対処については、まだ十分になされていないのが現状である。とくに重症化し、生命を脅かすような疾患については、小児や高齢者などが多くの被害を受けている。家庭内で十分に食糧の確保ができない際には、母親の健康状態に直接的に影響を及ぼし、特に妊産婦においては低体重児(出生体重が2500グラム以下)が増え、小児死亡率に直接影響している。低体重児の割合は世界では16%程であるが、その範囲は3~40%と大きく、特にバングラデシュなど南アジアで高くなっている。
 研究では、バングラデシュにおいて5,000人の女性を妊娠期から出生、その小児を10歳まで追跡した研究を国際共同研究として行った。今年は解析成果をセミナーや論文等で発表して行く予定である。
 この研究の成果が、新しいエビデンスの提供につながり、貧困や低栄養の多くの人口を抱える南アジア地域で、有効な介入手段に結びついてゆくことを期待している。

報告書

研究代表者
(所属)
我妻ゆき子(筑波大学 医学医療系)
研究関係者
(所属)
林 泰一(京都大学 防災研究所)、David Sack(The Johns Hopkins University) Md. Harunor Rahid (筑波大学 人間総合科学研究科)
研究期間 2014年7月~2015年3月
実績概要

 気候変動は今世紀最大のチャレンジ課題となっており、公衆衛生政策にもその重要性が年々高まっている。これまでの研究では、ある種の感染症や自然災害が増加することが言われている。しかし、多くの国ではそれらの被害を最小限にする対処については、まだ十分になされていないのが現状である。とくに重症化し、生命を脅かすような疾患については、小児や高齢者などが多くの被害を受けている。家庭内で十分に食糧の確保ができない際には、母親の健康状態に直接的に影響を及ぼし、特に妊産婦においては低体重児が増え、小児死亡率に直接影響している。低体重児の割合は世界では16%程であるが、その範囲は3~40%と大きく、特にバングラデシュなど南アジアで高くなっている。本研究では、バングラデシュにおいて5,000人の女性を妊娠期から出生、その小児を10歳まで追跡した研究を国際共同研究として行った。解析成果をセミナーや論文等で発表した。この研究の成果は、新しいエビデンスの提供につながり、貧困や低栄養の多くの人口を抱える南アジア地域で、有効な介入手段に結びついてゆくことが期待される。

活動内容・
研究成果

本研究の解析結果は、国際シンポジウムや、国際セミナー・ワークショップにて発表した。

・USJI Week 2015(ワシントンDC、2015年2月23日) において、日米研究者による気候変動に関する社会適応の政策決定について議論し成果発表を実施した。
セッション「貧困、低栄養と感染症制御への挑戦」
発表1: Malaria research in Bangladesh (David Sack, Johns Hopkins University)
発表2: Climate change impact on health (Yukiko Wagatsuma, University of Tsukuba)
発表3: Malnutrition and child health (Harunur Rashid, University of Tsukuba)

・2014 Global Health Workshop, organized by the Association of Pacific Rim Universities(Taipei, 2014年9月26日)
発表: Fetal growth and development: a life-course approach to health(Yukiko Wagatsuma, University of Tsukuba)

・Tsukuba Global Science Week 2014 “Solutions to Global Issues”(Tsukuba, 2014年9月29日)
発表1:Temperature during pregnancy influences birth size (Miki Kagami, University of Tsukuba)
発表2:The early marriage and maternal health care utilization in rural Bangladesh(Md. Harunor Rashid, University of Tsukuba

Policy Paper

研究代表者
(所属)
我妻ゆき子(筑波大学 医学医療系)
研究関係者
(所属)
林 泰一(京都大学 防災研究所)、David Sack(The Johns Hopkins University) Md. Harunor Rahid (筑波大学 人間総合科学研究科)
研究期間 2014年7月~2015年3月
タイトル Challenges against poverty, malnutrition and infectious diseases

Climate change is one of the defining challenges of the century and increasingly recognized as a public health policy. Previous studies reported the relationship between the increased risk of infections and climate related disasters. Many countries have a high burden of climate-sensitive diseases, but public health capability to respond is not always optimal. Major diseases that are sensitive to climate change often become serious among vulnerable population. Household food security and maternal malnutrition are known to be linked with child mortality and growth. Low birth weight (LBW; <2,500g) is a major determinant of mortality, morbidity and disability in neonates, infancy and childhood and has long term impact on health outcomes in adult life. The prevalence of LBW is estimated to be 16% worldwide with a range of 3-40% and occurs mostly in developing countries. The incidence of LBW in Bangladesh, predominantly the result of intrauterine growth restriction, is one of the highest in the world. This study aims to describe the impact of meteorological factors related to maternal and child malnutrition and child growth using a large birth cohort following 5,000 pregnancy mothers and their newborns in Bangladesh. The results would contribute to evidences on vicious cycle of poverty and malnutrition, and facilitate policies how to mitigate the impact of climate change among vulnerable population.

 

1.The Influence of Climatic Variability on Diarrheal Diseases

Introduction Diarrheal disease remains a remarkable factor that causes significant mortality annually, especially in developing countries. It is also anticipated that the global warming may further accelerate the increasing trend of epidemics in near future. Thus, it becomes more and more important to clarify the dynamics that control the epidemic of diarrheal diseases.

Objectives We aim to assess the impact of local and global climatic variability on diarrheal diseases.

Methods Diarrheal surveillance data used were daily diarrheal patient numbers from ICDDR,B Dhaka Hospital for over 22 years (1980-2001). Time scales of meteorological elements used were diurnal, intra-seasonal, seasonal and inter-annual variations. Lag-correlation and time-series regression models were used to assess an effect of meteorological phenomenon on the epidemiology of diarrheal diseases.

Results We identified several local, regional and global environmental factors that affect the epidemic peak of diarrheal patients. Regional climatologic and hydrological environmental factors associated with the late rainy epidemic correlate with regional anomalous atmospheric circulation patterns, i.e., stronger than normal local Hadley circulation, and stranger than normal Tibetan High. It indicates that El Niño/Southern Oscillation (ENSO) mode maturing in the preceding winter significantly correlates with the epidemics.

Conclusion The winter El Niño affects the epidemic in Dhaka in late rainy season, through the suppression of western North Pacific rainfall and the resultant anomalous South Asian monsoon circulation.

 

2.The Effect of Meteorological Factors on Fetal Growth

Introduction In the last decade, extreme weather events happened in various areas of the world. Many places recorded extremely hot summer in 2010. It has been concerned about the adverse effects of climate change on human health both directly and indirectly. Hajat et al. showed evidence of increased mortality in association with hot and cold weather [1]. Every person is at risk of climate change, and children are more vulnerable than adults to health risk from exposure to environmental hazards [2]. Low birth weight (LBW) is defined as a birth of less than 2500g and is a major determinant of mortality and morbidity in neonates, infancy and childhood. The incidence of LBW in the world is 16%, and most of LBW infants are born in developing countries [3]. Some studies reported seasonal variation of birth weight and length [4-7]. Murray et al. suggested that the relationship between lower birth weight and exposure to low winter temperature during mid-gestation [7]. However, it has not been certain whether which meteorological element has an effect upon birth weight and length. If meteorological elements have influence on fetal development, climate change will be a burden to fetus. The aim of this study is to examine whether temperature during pregnancy has an influence on fetal growth.

Materials and Methods

Study Area and Population Matlab is situated 50 km southeast of Dhaka, the capital city of Bangladesh. The area is a typical rural area of Bangladesh. The International Center for Diarrhoeal Disease Research, Bangladesh (ICDDR, B) has maintained a registration system of birth, death and migrations in Matlab Health and Demographic Surveillance (HDSS) site since 1966. In 2001, ICDDR, B and collaborative partners initiated the Maternal and Infant Nutrition Interventions in Matlab (MINIMat) study. It was a set of randomized trials that would improve maternal nutritional status through supplementation. Approximately 5,000 of pregnant women who lived in the area were recruited as early as 8 weeks of gestation from November 2001 to October 2003. This study used fetal growth data of 3,267 livebirth singleton infants. The study had fetal size parameters such as birth weight, birth length, head circumference (HC) and abdominal circumference (AC). HC and AC were measured by ultrasound at 14, 19 and 30 weeks of gestation. Mothers’ weight and height were also measured when they enrolled in the study, and the information such as age, parity and education status were collected. We also obtained meteorological data that included daily maximum and minimum temperatures, temperatures of every three hours, daily hours of sunlight, relative humidity and precipitation (every three hours) from 2001 to 2004, observed at Changpur observatory site of Bangladesh Meteorological Department.

Statistical Analysis First, the fetal data were divided into three categories by season (dry and cold; October – February, hot; March – May, monsoon; June – September) and into 12 categories by month at birth, then comparisons among group mean birth weight or length were conducted to see seasonal and monthly difference. Then, we calculated daily mean temperature and 2-week moving average temperature. Lag-correlation analyses were used to examine the relationship between birth weight and 2-week average temperature at different time points of gestation during pregnancy. The relationship for birth length was tested in a similar manner. Multivariate regression analyses was conducted to examine the relationship between birth size and 2-week moving average temperature, adjusted by sex of newborn, parity, BMI and education of mothers.

Results Of 3,267 livebirth singleton infants, about 30% of them were LBW. The incidence of preterm birth was 7.9%. Mean BMI of mothers was 20.2. 31% were primigrava. About one-third of mothers had received no formal schooling, and 27% had been educated for less than 6 years.

There were significant seasonal variation in birth weight and birth length (P<0.001). Infants born in winter were significantly shorter than those born in other seasons, and infants born in January and December had the shortest mean birth length. Winter-born infants, especially born in January and December, had also lower mean birth weight. However, infants with the lowest mean birth weight were observed in June and July (monsoon season). Significant negative correlation was observed between birth length and mean temperature at the 8 week to 26 week of gestation. On the other hand, for birth weight, significant negative correlation with temperature was found from 26 week to 30 week of gestation. After adjusted by sex of infant, BMI, parity and education of mother, the relationship was no more significant for birth weight.

Discussion Our study showed that if temperature increased at the 1st and the 2nd trimester, birth length was shorter. This is the first study to report the effect of temperature on birth length. Birth weight and birth length were vary by season as several studies reported in previous studies [4-7]. Seasonal variation was explained in a simple manner for birth length (colder is shorter). However, there was no significant seasonal difference for birth weight. It might be explained that birth weight is more affected by other meteorological elements such as precipitation than birth length.

Conclusion Fetal growth and size at birth are related to a variety of socioeconomic, nutritional, and environment factors. Yet, based on our result, higher mean temperature during pregnancy has negative association with size at birth. Although absolute effect in size is small, this effect is for everyone and possibly continues until adulthood (the theory of fetal origins of adult diseases has been confirmed [8-9]).

References

[1] Hajat, S., Kovats, R. and Lachowycz, K. (2007) Heat-related and cold-related deaths in England and Wales: who is at risk? Occup Environ Med.64,93-100.

[2] Pronczuk, J. and Surdu, S. (2008) Children’s environmental health in the twenty-first century. Ann. N. Y. Acad. Sci. 1140, 143-154.

[3] United Nations Children’s Fund (UNICEF). (2009) The State of the world’s children special edition statistics tables. p.15.

[4] Wohlfahrt, J., Melbye, M., Christens, P., Anderson, A. and Hjalgrim, H. (1998) Secular and seasonal variation of length and weight at birth. The Lancet. 352, 1990

[5] McGrath, J., Keeping, D., Saha, S., Chant, D., Lieberman, D. and O’Callaghan, M. (2005) Seasonal fluctuations in birth weight and neonatal limb length; does prenatal vitamin D influence neonatal size and shape? Early Human Development. 81, 609-618.

[6] Chodic, G., Shalev, V., Goren, I. and Inskip, P. (2007) Seasonality in birth weight in Israel: new evidence suggests several global patterns and different etiologies. Ann Epidemiol. 17, 440-446.

[7] Murray, L., O’Reilly, D.,Betts, N., Patterson, C., Smith, G. and Evans, A. (2000) Season and outdoor ambient temperature: effect on birth weight. Obstet Gynecol. 96, 689-695.

[8] Flouris, A., Spiropoulos, Y., Sakellariou, G. and Koutedakis, Y. (2009) Effect of seasonal programming

on fetal development and longevity: links with environment temperature. Am.J.Hum.Biol.21,214-216.

[9] Barker DJP. Mothers, babies, and diseases in later life. (1994). London:BMJ Publishing Group.

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