Hanako Iwashita

Hanako Iwashita


Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 February 2021 in Parasite Epidemiology and Control
Verified
Journal Article
Open access
HIHanako Iwashita
Hanako Iwashita
TSTetsuhiro Sugamoto
Tetsuhiro Sugamoto
TTTaichiro Takemura
Taichiro Takemura
ATAsako Tokizawa
Asako Tokizawa
TVThiem Dinh Vu
Thiem Dinh Vu
TYTetsu Yamashiro
Tetsu Yamashiro
Giardia spp. is detected frequently in humans and animals. Although many studies have been conducted on the epidemiology of giardiasis, there is a scarcity of information on the genetic diversity and the dynamics of transmission of Giardia spp. in Vietnam. The zoonotic potential of Giardia spp. remains elusive. The objective of this study was to determine the genetic diversity of Giardia spp. in both humans and livestock to assess the existence of a route of infection between livestock and humans. Our goal was to assess the role animals play in the epidemiology of human infection in northern Vietnam. In Hien Khanh commune in northern Vietnam, 311 households with 1508 residents were randomly selected for a diarrheal cohort study. Of these, 2120 human diarrheal samples were collected from 1508 residents in 2014 and 2017. Of these, non-diarrheal samples were cross-sectionally collected from 471 residents. At the same site, livestock samples from buffalo, dairy and beef cattle, pigs, and dogs were collected. All stool samples were examined for Giardia spp. by Direct Immunofluorescence Assay (DFA) using fluorescent microscope. DNA extraction, PCR analysis of the 3 genes (bg, gdh, tpi), and sequencing analysis were continuously carried out. A total of 23 animal stool samples, 8 human non-diarrheal samples, and 36 human diarrheal samples were Giardia spp. were positive by PCR using the bg and gdh genes. Giardia spp. assemblage AII and E were detected in both animal samples and human samples in this study site. The detection of assemblage E in human stool samples suggests the first human case report in Vietnam. We assume that the unexpected human infection of all Giardia assemblages including A, B, and E may be due to an environment contaminated with animal and human feces in this village.

1 August 2021 in Parasitology International
Verified
Journal Article
Closed access
HIHanako Iwashita
Hanako Iwashita
TTTaichiro Takemura
Taichiro Takemura
ATAsako Tokizawa
Asako Tokizawa
TSTetsuhiro Sugamoto
Tetsuhiro Sugamoto
VTVu Dinh Thiem
Vu Dinh Thiem
TYTetsu Yamashiro
Tetsu Yamashiro

HIHanako Iwashita
Hanako Iwashita
ATAsako Tokizawa
Asako Tokizawa
TVThiem Dinh Vu
Thiem Dinh Vu
TTTaichiro Takemura
Taichiro Takemura
TNTuan Hai Nguyen
Tuan Hai Nguyen
TYTetsu Yamashiro
Tetsu Yamashiro
In Vietnam, data on the risk factors for diarrhea at the community level remain sparse. This study aimed to provide an overview of diarrheal diseases in an agricultural community in Vietnam, targeting all age groups. Specifically, we investigated the incidence of diarrheal disease at the community level and described the potential risk factors associated with diarrheal diseases. In this prospective cohort study, a total of 1508 residents were enrolled during the 54-week study period in northern Vietnam. The observed diarrheal incidence per person-year was 0.51 episodes. For children aged <5 years, the incidence per person-year was 0.81 episodes. Unexpectedly, the frequency of diarrhea was significantly higher among participants who used tap water for drinking than among participants who used rainwater. Participants who used a flush toilet had less frequent diarrhea than those who used a pit latrine. The potential risk factors for diarrhea included the source of water used in daily life, drinking water, and type of toilet. However, the direct reason for the association between potential risk factors and diarrhea was not clear. The infection routes of diarrheal pathogens in the environment remain to be investigated at this study site.

19 July 2024 in PLOS Global Public Health
Verified
Journal Article
Open access
PDF file
HIHanako Iwashita
Hanako Iwashita
RSRabina Shrestha
Rabina Shrestha
UYUday Narayan Yadav
Uday Narayan Yadav
ASAbha Shrestha
Abha Shrestha
DMDeepa Makaju
Deepa Makaju
TSTomohiko Sugishita
Tomohiko Sugishita
Global healthcare systems have faced unprecedented strain due to the COVID-19 pandemic, with a profound impact on individuals with non-communicable diseases (NCDs), a scenario particularly pronounced in low-income countries like Nepal. This study aimed to understand the experiences of and challenges faced by patients with NCDs in Nepal during the pandemic, focusing on healthcare service availability and identifying factors affecting healthcare use, with the goal of being prepared for future emergencies. This study utilized a telephonic survey of 102 patients with NCDs and 10 qualitative interviews with healthcare providers in the Kavrepalanchok and Nuwakot districts of Nepal. We used mixed methods, with both qualitative and quantitative approaches. Specifically, multiple correspondence analysis, hierarchical cluster analysis, and classification tree analysis were used as exploratory methods. The study revealed that while 69.6% of the participants reported no difficulty in obtaining medication, other questions revealed that 58.8% experienced challenges in accessing routine medical care. Major barriers, such as fear of infection, unavailability of medicine in rural areas, and lack of transportation, were found through the qualitative interviews. Meanwhile, participants identified innovative strategies, such as telemedicine and community-based awareness programs, as potential facilitators for addressing barriers that arise during pandemic situations such as COVID-19. The COVID-19 pandemic exacerbated challenges in accessing healthcare services for patients with NCDs in Nepal. Our findings suggest the need to design and implement telemedicine services for patients with NCDs, as well as community-based programs that aim to improve health literacy, encourage healthy behavior, prevent development of NCDs, and ensure continuity of care during such crises, especially in countries with limited resources.

4 December 2020 in Research Square
Verified
Preprint
Open access
PDF file
HIHanako Iwashita
Hanako Iwashita
TTTaichiro Takemura
Taichiro Takemura
ATAsako Tokizawa
Asako Tokizawa
TSTetsuhiro Sugamoto
Tetsuhiro Sugamoto
DVDinh Thiem Vu
Dinh Thiem Vu
TYTetsu Yamashiro
Tetsu Yamashiro
BackgroundCryptosporidium spp. is a protozoan parasite with worldwide distribution that causes cryptosporidiosis in humans and other animals. In the countryside of northern Vietnam, where free-roaming livestock are widespread, cryptosporidiosis is an important zoonotic disease. However, there have been few studies of cryptosporidiosis in Southeast Asia from the perspective of zoonotic disease epidemiology. The purpose of this study was to investigate the occurrence of Cryptosporidium infection in both humans and animals and to gain an awareness of the potential threat posed by this zoonotic infection in northern Vietnam.Methods We conducted a community survey to collect information about cases of diarrhea in an agricultural area of northern Vietnam. For this study, a total of 2715 samples (2120 human diarrheal samples, 471 non-diarrheal human samples, and 124 animal stool samples) were collected. A direct immunofluorescence assay (DFA) was used to detect Cryptosporidium spp. oocysts in concentrated stool samples by observation under a fluorescent microscope. DNA extraction, PCR amplification of the three genes (COWP, SSU-rRNA, and GP60), and sequencing analysis were performed to identify Cryptosporidium spp.Results Of 2715 samples, 15 samples (10 diarrheal samples, 2 non-diarrheal samples, and 3 animal stool samples) tested positive by PCR for the COWP gene. Three species of Cryptosporidium spp. were detected; C. canis (from six human diarrheal samples, two human non-diarrheal samples, and one dog sample); C. hominis (from four human diarrheal samples); and C. suis (from two pig samples). In terms of C. hominis, the GP60 subtype IeA12G3T3 was detected in all four human diarrheal samples.Conclusions Although the number of positive samples was very small, our epidemiological data showed that the emerging pattern of each of the three species (C. canis, C. hominis, and C. suis) was different at this study site. For example, zoonotic transmission of C. canis, between dogs and humans was suspected. Further studies are needed to assess the risk of oocyst contamination in the wider environment, including water, in this study area.

22 October 2025 in Malaria Journal
Verified
Journal Article
Open access
PDF file
HIHanako Iwashita
Hanako Iwashita
SNSachiyo Nagi
Sachiyo Nagi
FBFelix Bahati
Felix Bahati
WKWataru Kagaya
Wataru Kagaya
PLPeter S. Larson
Peter S. Larson
AKAkira Kaneko
Akira Kaneko
Background: This study focused on the importance of long-lasting insecticide treated nets (LLINs) in malaria control in a study area where socio-economic disparities are widening. The objective was to assess the effectiveness of LLIN ownership when nets were available for no more than two people, controlling for differences in socio-economic status (SES). It was hypothesized that LLIN effectiveness would differ by SES and that LLIN effectiveness should be analysed with adjustment for differences in SES. Methods: A household level survey was conducted in an area in the Lake Victoria region in Suba North Sub-County, Homa Bay County, Western Kenya between June and September 2021. Through the household survey, the number of people living in the home, the number of LLINs, and demographic data were recorded. The ratio of the number of people reporting sleeping in the house to the total number of LLINs in the home was calculated. Through a school-based malaria survey, researchers administered blood-spot, PCR tests for Plasmodium infection. Community workers linked individual malaria tests to homes that were involved in the household survey through names and geographic identifiers. A generalized linear model (GLM) tested the associations between household parasitaemia risk in children and the ratio of people to LLINs, stratifying on asset-based household level SES measures. Results: The association between sufficient LLIN ownership and household malaria infection status was analysed across SES groups. In middle SES households, sufficient LLIN ownership was significantly associated with lower malaria infection status compared with insufficient LLIN ownership (OR 0.32, 95% CI 0.12–0.92). In the low SES group, a similar trend was observed, although it was not statistically significant (OR 0.59, 95% CI 0.15–2.91). When middle and low SES groups were combined, sufficient LLIN ownership remained significantly associated with lower incidence (OR 0.37, 95% CI 0.17–0.87). Conclusions: The results suggest that promoting the use of one LLIN by no more than two people, as recommended by WHO, can reduce the risk of malaria. Efforts to promote LLINs as an effective means of preventing malaria in children might encourage LLIN compliance and maintain community level control targets. If households have been excluded from LLIN distribution, LLINs should be distributed immediately along with information about their effectiveness. The effectiveness of LLINs varies by region, but strategies to sustain LLIN use should be recognized as contributing to benefits for the entire community.