Detecting Foci of Malaria Transmission with School Surveys: A Pilot Study in the Gambia.

BACKGROUND: In areas of declining malaria transmission such as in The Gambia, the identification of malaria infected individuals becomes increasingly harder. School surveys may be used to identify foci of malaria transmission in the community. METHODS: The survey was carried out in May-June 2011, before the beginning of the malaria transmission season. Thirty two schools in the Upper River Region of The Gambia were selected with probability proportional to size; in each school approximately 100 children were randomly chosen for inclusion in the study. Each child had a finger prick blood sample collected for the determination of antimalarial antibodies by ELISA, malaria infection by microscopy and PCR, and for haemoglobin measurement. In addition, a simple questionnaire on socio-demographic variables and the use of insecticide-treated bed nets was completed. The cut-off for positivity for antimalarial antibodies was obtained using finite mixture models. The clustered nature of the data was taken into account in the analyses. RESULTS: A total of 3,277 children were included in the survey. The mean age was 10 years (SD = 2.7) [range 4-21], with males and females evenly distributed. The prevalence of malaria infection as determined by PCR was 13.6% (426/3124) [95% CI = 12.2-16.3] with marked variation between schools (range 3-25%, p<0.001), while the seroprevalence was 7.8% (234/2994) [95%CI = 6.4-9.8] for MSP119, 11.6% (364/2997) [95%CI = 9.4-14.5] for MSP2, and 20.0% (593/2973) [95% CI = 16.5-23.2) for AMA1. The prevalence of all the three antimalarial antibodies positive was 2.7% (79/2920). CONCLUSIONS: This survey shows that malaria prevalence and seroprevalence before the transmission season were highly heterogeneous

Spillway discharges by modification of weir shapes and overflow surroundings

Almost all spillways of mid-size dams in Korea are overflow weir. To investigate the flood control capacity of overflow spillway, 3D numerical simulations were analyzed the discharge of a dam spillway for different weir shapes. Hydraulic model experiments, downsized as scale factor of 40 to 1 by Froude similitude were also carried out to verify the numerical results. Overflow phases and discharges of the linear labyrinth weir and the curved labyrinth weir were compared with those of the linear ogee weir. It was found that the discharge of the labyrinth weir was 71 % greater than that of the linear ogee weir at low reservoir elevation because the labyrinth weir had a longer effective length. However, as the elevation of the water surface rose, the discharge slope of the labyrinth weir became milder by submergence and nappe interference in the side channel. Structural modification of the overflow surroundings such as changing the approaching channel elevation, lowering the bed elevation of the side channel, and moving the weir structure toward the reservoir were also considered to examine the discharge capacity of the spillway. Lowering the bed elevation of the side channel was found to be the most effective option.OAIID:RECH_ACHV_DSTSH_NO:T201636126RECH_ACHV_FG:RR00200001ADJUST_YN:EMP_ID:A080988CITE_RATE:1.569FILENAME:pub09_Seo_etal_2016EES.pdfDEPT_NM:건설환경공학부EMAIL:[email protected]_YN:YFILEURL:https://srnd.snu.ac.kr/eXrepEIR/fws/file/9c948ad0-91a5-4559-8ff8-c4a827fb6c67/linkN