フィリピン・パラワン州におけるマラリア顕微鏡検査技師の役割と限界

学位の種別:課程博士University of Tokyo(東京大学

フィリピン・パラワン州におけるマラリア顕微鏡検査技師の役割と限界

学位の種別:課程博士University of Tokyo(東京大学

Deforestation inhibits malaria transmission in Lao PDR: a spatial epidemiology using Earth observation satellites

Abstract Background The present study aimed to analyze the impact of deforestation on the malaria distribution in the Lao People’s Democratic Republic (Lao PDR), with consideration of climate change. Methods Malaria distribution data from 2002 to 2015 were obtained from the Ministry of Health of Lao PDR and each indicator was calculated. Earth observation satellite data (forested area, land surface temperature, and precipitation) were obtained from the Japan Aerospace Exploration Agency (JAXA). Structured equation modeling (SEM) was conducted to clarify the relationship between the malaria incidence and Earth observation satellite data. Results As a result, SEM identified two factors that were independently associated with the malaria incidence: area and proportion of forest. Specifically, malaria was found to be more prevalent in the southern region, with the malaria incidence increasing as the percentage of forested land increased (both p < 0.01). With global warming steadily progressing, forested areas are expected to play an important role in the incidence of malaria in Lao PDR. This is believed because malaria in Lao PDR is mainly forest malaria transmitted by Anopheles dirus. Conclusion To accelerate the elimination of malaria in Lao PDR, it is important to identify, prevent, and intervene in places with increased forest coverage (e.g., plantations) and in low-temperature areas adjacent to malaria-endemic areas, where the vegetation is similar to that in malaria-endemic areas

Bottom-up approach to strengthen community-based malaria control strategy from community health workers’ perceptions of their past, present, and future: a qualitative study in Palawan, Philippines

Abstract Background Microscopists have active roles in bringing malaria diagnosis and treatment closer to households in Palawan, the highest malaria-endemic province in the Philippines. To accelerate the elimination of malaria in Palawan, we performed a study based on the bottom-up approach to provide profound data to strengthen this community-based malaria control from the microscopists’ point of view. Methods We performed a qualitative cross-sectional study in Palawan. Four focus group discussions with 50 microscopists were conducted in Palawan from November 2010 to February 2011. During the discussions, the following open-ended questions were addressed: motivation for applying to be microscopists in the “Past” category; job satisfaction, role, problems, and saddest and happiest experiences working as microscopists in the “Present” category; and willingness towards task shifting in the “Future” category. Data were transcribed and analyzed by framework analysis using the NVivo software program. Results The present study innovatively proposed the following strategies: reinforcement strategy (adequate supplies and settings), highly prioritized additional strategies (improving social status of microscopists, issuing a travel budget, and including indigenous populations), regional additional strategies (additional malaria control in the southern region and task shifting in the northern region), and less prioritized additional strategies (employment policy and health checkup). Conclusion A bottom-up approach using microscopists’ perceptions would be a valuable method to propose practical and effective additional strategies for strengthening community-based malaria control

Impact of precipitation on the prevalence of schistosomiasis mekongi in Lao PDR: Structural equation modelling using Earth observation satellite data

Increasing attention is being given to the effect of climate change on schistosomiasis, but the impact is currently unknown. As the intermediate snail host (Neotricula aperta) of Schistosoma mekongi inhabits the Mekong River, it is thought that environmental factors affecting the area of water will have an impact on the occurrence of schistosomiasis mekongi. The aim of the present study was to assess the impact of precipitation on the prevalence of human schistosomiasis mekongi using epidemiological data and Earth observation satellite data in Khong district, Champasak province, Lao PDR. Structural equation modelling (SEM) using epidemiological data and Earth observation satellite data was conducted to determine the factors associated with the number of schistosomiasis mekongi patients. As a result, SEM identified 3 significant factors independently associated with schistosomiasis mekongi: (1) a negative association with mass drug administration (MDA); (2) negative association with total precipitation per year; and (3) positive association with precipitation during the dry season. Precisely, regardless of MDA, the increase in total yearly precipitation was suggested to decrease the number of schistosomiasis patients, whereas an increase in precipitation in the dry season increased the number of schistosomiasis patients. This is probably because when total precipitation increases, the water level of the Mekong River rises, thus decreasing the density of infected larvae, cercaria, in the water, and the frequency of humans entering the river would also decrease. In contrast, when precipitation in the dry season is higher, the water level of the Mekong River also rises, which expands the snail habitant, and thus water contact between humans and the snails would also increase. The present study results suggest that increasing precipitation would impact the prevalence of schistosomiasis both positively and negatively, and precipitation should also be considered in the policy to eliminate schistosomiasis mekongi in Lao PDR

Patient Knowledge on Malaria Symptoms Is a Key to Promoting Universal Access of Patients to Effective Malaria Treatment in Palawan, the Philippines

<div><p>Introduction</p><p>Palawan, where health care facilities are still limited, is one of the most malaria endemic provinces in the Philippines. Since 1999, microscopists (community health workers) have been trained in malaria diagnosis and feasibility of early diagnosis and treatments have been enhanced throughout the province. To accelerate the universal access of malaria patients to diagnostic testing in Palawan, positive health seeking behavior should be encouraged when malaria infection is suspected.</p><p>Methods</p><p>In this cross-sectional study, structured interviews were carried out with residents (N = 218) of 20 remote malaria-endemic villages throughout Palawan with a history of suspected malaria from January to February in 2012. Structural equation modeling (SEM) was conducted to determine factors associated with appropriate treatment, which included: (1) socio-demographic characteristics; (2) proximity to a health facility; (3) health seeking behavior; (4) knowledge on malaria; (5) participation in community awareness-raising activities.</p><p>Results</p><p>Three factors independently associated with appropriate treatment were identified by SEM (CMIN = 10.5, df = 11, CFI = 1.000, RMSEA = .000): “living near microscopist” (<i>p</i> < 0.001), “not living near private pharmacy” (<i>p</i> < 0.01), and “having severe symptoms” (<i>p</i> < 0.01). “Severe symptoms” were positively correlated with more “knowledge on malaria symptoms” (<i>p</i> < 0.001). This knowledge was significantly increased by attending “community awareness-raising activities by microscopists” (<i>p</i> < 0.001).</p><p>Conclusions</p><p>In the resource-limited settings, microscopists played a significant role in providing appropriate treatment to all participants with severe malaria symptoms. However, it was considered that knowledge on malaria symptoms made participants more aware of their symptoms, and further progressed self-triage. Strengthening this recognition sensitivity and making residents aware of nearby microscopists may be the keys to accelerating universal access to effective malaria treatment in Palawan.</p></div

The detection of cryptic Plasmodium infection among villagers in Attapeu province, Lao PDR.

Although the malaria burden in the Lao PDR has gradually decreased, the elimination of malaria by 2030 presents many challenges. Microscopy and malaria rapid diagnostic tests (RDTs) are used to diagnose malaria in the Lao PDR; however, some studies have reported the prevalence of sub-microscopic Plasmodium infections or asymptomatic Plasmodium carriers in endemic areas. Thus, highly sensitive detection methods are needed to understand the precise malaria situation in these areas.A cross-sectional malaria field survey was conducted in 3 highly endemic malaria districts (Xaysetha, Sanamxay, Phouvong) in Attapeu province, Lao PDR in 2015, to investigate the precise malaria endemicity in the area; 719 volunteers from these villages participated in the survey. Microscopy, RDTs and a real-time nested PCR were used to detect Plasmodium infections and their results were compared. A questionnaire survey of all participants was also conducted to estimate risk factors of Plasmodium infection. Numbers of infections detected by the three methods were microscopy: P. falciparum (n = 1), P. vivax (n = 2); RDTs: P. falciparum (n = 2), P. vivax (n = 3); PCR: Plasmodium (n = 47; P. falciparum [n = 4], P. vivax [n = 41], mixed infection [n = 2]; 6.5%, 47/719). Using PCR as a reference, the sensitivity and specificity of microscopy were 33.3% and 100.0%, respectively, for detecting P. falciparum infection, and 7.0% and 100.0%, for detecting P. vivax infection. Among the 47 participants with parasitemia, only one had a fever (≥37.5°C) and 31 (66.0%) were adult males. Risk factors of Plasmodium infection were males and soldiers, whereas a risk factor of asymptomatic Plasmodium infection was a history of ≥3 malaria episodes.There were many asymptomatic Plasmodium carriers in the study areas of Attapeu province in 2015. Adult males, probably soldiers, were at high risk for malaria infection. P. vivax, the dominant species, accounted for 87.2% of the Plasmodium infections among the participants. To achieve malaria elimination in the Lao PDR, highly sensitive diagnostic tests, including PCR-based diagnostic methods should be used, and plans targeting high-risk populations and elimination of P. vivax should be designed and implemented

Map of Annual Parasite Incidence (API) (confirmed infections/1,000 population at risk) by municipalities, 2010.

<p>This map was constructed by the authors based on the data of provincial health report 2010 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127858#pone.0127858.ref005" target="_blank">5</a>].</p