日本の小児患者におけるノロウイルスの研究 : 疫学、遺伝的多様性、組織血液型抗原との結合特異性の構造解析

学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 渡辺 知保, 東京大学講師 安岡 潤子, 東京大学准教授 渡邊 洋一, 東京大学教授 甲斐 知惠子, 東京大学講師 加藤 元博University of Tokyo(東京大学

A Qualitative Exploration of Exclusive Breastfeeding Practices Among Karen Ethnicity Mothers in Northern Thailand Remote Rural Areas

Low exclusive breastfeeding rates among the Karen ethnic group in Northern Thailand's remote rural areas underscore the need to understand knowledge, attitudes, and social support to develop targeted interventions. This qualitative study examined exclusive breastfeeding practices and the factors influencing breastfeeding behavior among 14 Karen Ethnicity Mothers (KEMs) in Northern Thailand. A structured interview was used to collect the data, a triangular method to determine the data's validity, and a content analysis method to examine the data revealed seven themes and 14 subthemes. This study identified three key factors for successful breastfeeding: self-motivation, social support, and effective problem management, which included overcoming the family's anti-breastfeeding beliefs. Conversely, unsuccessful breastfeeding stemmed from four issues: inadequate maternal knowledge and misconceptions, family beliefs and culture, maternal health problems, and economic constraints. Therefore, the success of breastfeeding was heavily influenced by both personal and environmental factors. As a result, every KEM should be encouraged to recognize the importance of breastfeeding and to exclusively breastfeed for at least six months, especially those living in remote rural areas and have a different way of life than the natives

Mandarin farmers' knowledge, attitudes, and practices related to antibiotic use in mandarin orchards and the presence of antibiotic-resistant bacteria in mandarin orchard workers in Fang district, Chiang Mai province, Thailand

Background and Aim: Inappropriate antibiotic use in the agricultural sector is a crucial driver of antibiotic resistance which is a global public health concern. Although there are many studies on antibiotic use in livestock production, studies on antibiotic use in crop production are relatively scarce. This study aimed to determine farmers' knowledge, attitudes, and practices (KAP) toward antibiotic use in Mandarin orchard and investigate their associations with the antibiotic susceptibility patterns among Mandarin orchard farmers in Fang District, Chiang Mai Province, Thailand. Materials and Methods: This cross-sectional study was conducted in Fang District between November and December 2021. The participants in this study were 151 farmers (farm owners and farm workers) in ten Mandarin orchards. All participants completed face-to-face interviews using a structured questionnaire. Nasal swabs were collected from 100 participants. The disk diffusion and staphylococcal chromosome cassette mec typing methods were used to test the antibiotic susceptibility of the isolates. Results: All farmers involved in the activities related to antibiotic exposure, 39.7% prepared or mixed antibiotics, and 82.8% injected antibiotics into Mandarin trees. Overall, farmers in this study had moderate levels of knowledge and attitudes and good antibiotic use practices. There was a significant association between attitudes and practices (r = 0.312, p < 0.001). In the analysis of drug resistance of the bacterial isolates, Staphylococcus aureus was detected in 16 of 100 nasal swab samples, with resistance to penicillin (16/16), methicillin (cefoxitin) (1/16), and tetracycline (6/16). Conclusion: This is the first report on farmers' and farm workers' KAP and antibiotic use in crop production, specifically Mandarin production. The findings of this research will help in developing plans and strategies to encourage the appropriate use of antibiotics and prevent antibiotic resistance or microbial resistance in plant production

Intergenogroup Recombinant Sapovirus in Japan, 2007–2008

We investigated the incidence of sapovirus (SaV)–associated gastroenteritis in infants and children in Japan during 2007–2008 and characterized the diversity of SaV-positive strains. SaV was detected in 19 (4%) of 477 fecal specimens. The leading genogroup (79%, 15 cases) comprised intergenogroup recombinant SaVs (GII/GIV)

Genetic characterisation of Norovirus strains in outpatient children from rural communities of Vhembe district / South Africa, 2014-2015

Background: Norovirus (NoV) is now the 24 most common causes of both outbreaks and sporadic non-bacterial gastroenteritis worldwide. However, data supporting the role of NoV in diarrheal disease are limited in the African continent. Objectives: This study investigates the distribution of NoV genotypes circulating in outpatient children from rural communities of Vhembe district / South Africa. Study design: Stool specimens were collected from children under five years of age with diarrhea, and controls without diarrhea, between July 2014 and April 2015. NoV positive samples, detected previously by Realtime PCR, were analysed using conventional RT-PCR targeting the partial capsid and polymerase genes. Nucleotide sequencing methods were performed to genotype the strains. Results: The sequence analyses demonstrated multiple NoV genotypes including GI.4 (13.8%), GI.5 (6.9%), GII.14 (6.9%), GII.4 (31%), GII.6 (3.4%), GII.P15 (3.4%), GII.P21 (3.4%) and GII.Pe (31%). The most prevalent NoV genotypes were GII.4 Sydney 2012 variants (n=7) among the capsid genotypes, GII.Pe (n=9) among the polymerase genotypes and GII.Pe/GII.4 Sydney 2012 (n=8) putative recombinants among the RdRp/Capsid genotypes. Two unassigned GII.4 variants were found. Conclusions: The findings highlighted NoV genetic diversity and revealed continuous pandemic spread and predominance of GII.Pe/GII.4 Sydney 2012, indicative of increased NoV activity. An unusual RdRp genotype GII.P15 and two unassigned GII.4 variants were also identified from rural settings of the Vhembe district/South Africa. NoV surveillance is warranted to help to inform investigations into NoV evolution and disease burden, and to support on-going vaccine development programmes

Increased Detection of Emergent Recombinant Norovirus GII.P16-GII.2 Strains in Young Adults, Hong Kong, China, 2016–2017

A new recombinant norovirus GII.P16-GII.2 outnumbered pandemic GII.4 as the predominant GII genotype in the winter of 2016–2017 in Hong Kong, China. Half of hospitalized case-patients were older children and adults, including 13 young adults. This emergent norovirus targets a wider age population compared with circulating pandemic GII.4 strains

Epidemiology of Sapovirus Infections in a Birth Cohort in Peru

Background: Sapovirus is one of the primary viral causes of acute gastroenteritis (AGE), especially where rotavirus vaccination has been implemented. The characteristics and impact of natural infection at the community level, however, have not been well documented. Methods: Stool samples were analyzed from 100 children randomly selected from a community-based birth cohort study in Peru. All diarrheal and 1 nondiarrheal stools collected trimonthly from children up to age 2 years (n = 1669) were tested for sapovirus detection. Viral shedding duration was determined by testing additional weekly samples (n = 440) collected before and after a sapovirus-positive sample. Results: The incidence of sapovirus infection in the first and second years of life was 4.3 and 11.1 per 100 child-months, respectively. By age 2 years, 82% of children had at least 1 sapovirus infection, and 64% had at least 1 sapovirus-associated diarrhea episode. The median shedding period was 18.5 days. In 112 of 175 infections, 14 genotypes from 4 genogroups (GI, GII, GIV, and GV) were determined. Among genogroups, GI were more frequently found in symptomatic infections than in asymptomatic infections (odds ratio, 3.1; 95% confidence interval, 1.3–7.4). Fifty-nine children had serial sapovirus infections, but only 3 had repeated infection of the same genotype. Conclusions: Sapovirus was frequently detected in children with AGE at the community level during the first 2 years of life. Serial sapovirus infections by multiple genotypes in a child suggest genotype-specific immunity from each infection, which needs to be taken into account for vaccine development