A Comparison of Aquatic Invertebrate Diversity between Paddy Fields under Traditional and Modern Management in Western Japan

We compared aquatic invertebrate diversity in paddy fields under traditional and modern management practices. We also examined the general factors that may be related to diversity within each paddy field. The Kitadan area was farmed with traditional management practices, with much longer periods of irrigations compared with the Kahoku area, which was farmed with modern agricultural practices using intermittent irrigation. We measured physicochemical factors and collected aquatic invertebrates from the two areas. Collected animal specimens were taxonomically identified and classified based by desiccation tolerance ability. At Kitadan, the total biodiversity parameters increased over time, while, biodiversity fluctuated temporally at Kahoku. The mean Shannon-Wiener diversity index was higher at Kitadan than at Kahoku. However, the mean taxon richness was not significantly different between locations. Both paddy fields were dominated by highly desiccation-tolerant invertebrates at the beginning of the rice cultivation period. Over time, the ratio of desiccation-sensitive invertebrates increased more at Kitadan than at Kahoku. Our canonical correspondence analysis showed that the time since rice transplanting, water permanence, pH, water depth, and chlorophyll a were significant factors affecting faunal assemblage composition. Our results indicate that water management practices have important roles in the aquatic biodiversity of paddy-field ecosystems

Determining the efficacy of guppies and pyriproxyfen (Sumilarv® 2MR) combined with community engagement on dengue vectors in Cambodia: study protocol for a randomized controlled trial.

BACKGROUND: Evidence on the effectiveness of low-cost, sustainable, biological vector-control tools for the Aedes mosquitoes is limited. Therefore, the purpose of this trial is to estimate the impact of guppy fish (guppies), in combination with the use of the larvicide pyriproxyfen (Sumilarv® 2MR), and Communication for Behavioral Impact (COMBI) activities to reduce entomological indices in Cambodia. METHODS/DESIGN: In this cluster randomized controlled, superiority trial, 30 clusters comprising one or more villages each (with approximately 170 households) will be allocated, in a 1:1:1 ratio, to receive either (1) three interventions (guppies, Sumilarv® 2MR, and COMBI activities), (2) two interventions (guppies and COMBI activities), or (3) control (standard vector control). Households will be invited to participate, and entomology surveys among 40 randomly selected households per cluster will be carried out quarterly. The primary outcome will be the population density of adult female Aedes mosquitoes (i.e., number per house) trapped using adult resting collections. Secondary outcome measures will include the House Index, Container Index, Breteau Index, Pupae Per House, Pupae Per Person, mosquito infection rate, guppy fish coverage, Sumilarv® 2MR coverage, and percentage of respondents with knowledge about Aedes mosquitoes causing dengue. In the primary analysis, adult female Aedes density and mosquito infection rates will be aggregated over follow-up time points to give a single rate per cluster. This will be analyzed by negative binomial regression, yielding density ratios. DISCUSSION: This trial is expected to provide robust estimates of the intervention effect. A rigorous evaluation of these vector-control interventions is vital to developing an evidence-based dengue control strategy and to help direct government resources. TRIAL REGISTRATION: Current Controlled Trials, ID: ISRCTN85307778 . Registered on 25 October 2015

Entomological outcomes of cluster-randomised, community-driven dengue vector-suppression interventions in Kampong Cham province, Cambodia

Cambodia has one of the highest dengue infection rates in Southeast Asia. Here we report quantitative entomological results of a large-scale cluster-randomised trial assessing the impact on vector populations of a package of vector control interventions including larvivorous guppy fish in household water containers, mosquito trapping with gravid-ovitraps, solid waste management, breeding-container coverage through community education and engagement for behavioural change, particularly through the participation of school children. These activities resulted in major reductions in Container Index, House Index, Breteau Index, Pupal Index and Adult Index (all p-values 0.002 or lower) in the Intervention Arm compared with the Control Arm in a series of household surveys conducted over a follow-up period of more than one year, although the project was not able to measure the longer-term sustainability of the interventions. Despite comparative reductions in Adult Index between the study arms, the Adult Index was higher in the Intervention Arm in the final household survey than in the first household survey. This package of biophysical and community engagement interventions was highly effective in reducing entomological indices for dengue compared with the control group, but caution is required in extrapolating the reduction in household Adult Index to a reduction in the overall population of adult Aedes mosquitoes, and in interpreting the relationship between a reduction in entomological indices and a reduction in the number of dengue cases. The package of interventions should be trialled in other locations

Ability of the Premise Condition Index to Identify Premises with Adult and Immature Aedes Mosquitoes in Kampong Cham, Cambodia.

Aedes-transmitted diseases, especially dengue, are increasing throughout the world and the main preventive methods include vector control and the avoidance of mosquito bites. A simple Premise Condition Index (PCI) categorizing shade, house, and yard conditions was previously developed to help prioritize households or geographical areas where resources are limited. However, evidence about the accuracy of the PCI is mixed. The current study aimed to contribute to a better understanding of the relevance by collecting data from 2,400 premises at four time points over 1 year in Kampong Cham, Cambodia. Regression models were then used to identify associations between PCI and Aedes adult female mosquitoes and pupae. In addition, receiver operating characteristic curves were used to measure the ability of PCI to identify premises in the top quartile of mosquito abundance. The density of adult Aedes females was positively associated with PCI at the household (ratio of means = 1.16 per point on the PCI scale) and cluster level (ratio of means = 1.54). However, the number of Aedes pupae was negatively associated with PCI at the household level (rate ratio = 0.74) and did not have a statistically significant association at the cluster level. Receiver operating characteristic curves suggest the PCI score had "rather low accuracy" (area under the ROC curve = 0.52 and 0.54) at identifying top-quartile premises in terms of adult female Aedes and pupae, respectively. These results suggest that caution is warranted in the programmatic use of PCI in areas of similar geography and mosquito abundance

Dengue knowledge, attitudes and practices and their impact on community-based vector control in rural Cambodia.

BACKGROUND: Globally there are an estimated 390 million dengue infections per year, of which 96 million are clinically apparent. In Cambodia, estimates suggest as many as 185,850 cases annually. The World Health Organization global strategy for dengue prevention aims to reduce mortality rates by 50% and morbidity by 25% by 2020. The adoption of integrated vector management approach using community-based methods tailored to the local context is one of the recommended strategies to achieve these objectives. Understanding local knowledge, attitudes and practices is therefore essential to designing suitable strategies to fit each local context. METHODS AND FINDINGS: A Knowledge, Attitudes and Practices survey in 600 randomly chosen households was administered in 30 villages in Kampong Cham which is one of the most populated provinces of Cambodia. KAP surveys were administered to a sub-sample of households where an entomology survey was conducted (1200 households), during which Aedes larval/pupae and adult female Aedes mosquito densities were recorded. Participants had high levels of knowledge regarding the transmission of dengue, Aedes breeding, and biting prevention methods; the majority of participants believed they were at risk and that dengue transmission is preventable. However, self-reported vector control practices did not match observed practices recorded in our surveys. No correlation was found between knowledge and observed practices either. CONCLUSION: An education campaign regarding dengue prevention in this setting with high knowledge levels is unlikely to have any significant effect on practices unless it is incorporated in a more comprehensive strategy for behavioural change, such a COMBI method, which includes behavioural models as well as communication and marketing theory and practice. TRIAL REGISTRATION: ISRCTN85307778

Entomological outcomes of clusterrandomised, community-driven dengue vector-suppression interventions in Kampong Cham province, Cambodia

Cambodia has one of the highest dengue infection rates in Southeast Asia. Here we report quantitative entomological results of a large-scale cluster-randomised trial assessing the impact on vector populations of a package of vector control interventions including larvivorous guppy fish in household water containers, mosquito trapping with gravid-ovitraps, solid waste management, breeding-container coverage through community education and engagement for behavioural change, particularly through the participation of school children. These activities resulted in major reductions in Container Index, House Index, Breteau Index, Pupal Index and Adult Index (all p-values 0.002 or lower) in the Intervention Arm compared with the Control Arm in a series of household surveys conducted over a follow-up period of more than one year, although the project was not able to measure the longer-term sustainability of the interventions. Despite comparative reductions in Adult Index between the study arms, the Adult Index was higher in the Intervention Arm in the final household survey than in the first household survey. This package of biophysical and community engagement interventions was highly effective in reducing entomological indices for dengue compared with the control group, but caution is required in extrapolating the reduction in household Adult Index to a reduction in the overall population of adult Aedes mosquitoes, and in interpreting the relationship between a reduction in entomological indices and a reduction in the number of dengue cases. The package of interventions should be trialled in other locations.The WHO Special Programme for Research and Training in Tropical Diseases (TDR).https://journals.plos.org/plosntdsdm2022UP Centre for Sustainable Malaria Control (UP CSMC

Field Efficacy of Larvivorous Fish and Pyriproxyfen Combined with Community Engagement on Dengue Vectors in Cambodia: A Randomized Controlled Trial.

Evidence on the effectiveness of low-cost, sustainable biological vector control tools for Aedes mosquitoes is limited. Therefore, the purpose of this trial was to estimate the impact of guppy fish in combination with the larvicide pyriproxyfen (PPF) (Sumilarv® 2MR) and communication for behavioral impact (COMBI) activities to reduce entomological indices in Cambodia. In this cluster randomized, controlled superiority trial, 30 clusters comprised of one or more villages each was allocated in a 1:1:1 ratio to receive either 1) all three interventions (guppies, PPF, and COMBI), 2) two interventions (guppies and COMBI), or 3) control (standard vector control). Entomological surveys among 40 randomly selected households per cluster were carried out quarterly. The primary outcome was the population abundance of adult female Aedes mosquitoes trapped using adult resting collections. In the primary analysis, adult female Aedes abundance and mosquito infection rates was aggregated over follow-up time points to give a single rate per cluster. These data were analyzed by negative binomial regression, yielding abundance ratios (ARs). The number of Aedes females was reduced roughly by half compared with the control in both the guppy, PPF, and COMBI arm (AR = 0.54; 95% CI, 0.34-0.85; P = 0.0073); and the guppy and COMBI arm (AR = 0.49; 95% CI, 0.31-0.77; P = 0.0021). The effectiveness demonstrated and extremely low cost of including fish rearing in community-based health structures suggest they should be considered as a vector control tool as long as the benefits outweigh any potential environmental concerns. Sumilarv® 2MR was also highly accepted and preferred over current vector control tools used in Cambodia

Location of the study site in a periurban area of Phnom Penh, Cambodia.

<p>Population density data are extracted from the WorldPop project [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005149#pntd.0005149.ref041" target="_blank">41</a>].</p

Summary of the ELISA and RT-PCR results of pig sera tested for Japanese encephalitis antibodies and virus RNA.

<p>Summary of the ELISA and RT-PCR results of pig sera tested for Japanese encephalitis antibodies and virus RNA.</p