Biomedical subjects

Sinuon Muth

Publications and source records attributed to Sinuon Muth.

3 recordsLinked to original sources

PubMed2006

Reader technique as a source of variability in determining malaria parasite density by microscopy.

BACKGROUND: Accurate identification and quantification of malaria parasites are critical for measuring clinical trial outcomes. Positive and negative diagnosis is usually sufficient for the assessment of therapeutic outcome, but vaccine or prophylactic drug trials require measuring density of infection as a primary endpoint. Microscopy is the most established and widely-used technique for quantifying parasite densities in the blood. METHODS: Results obtained by 24-27 expert malaria microscopists, who had independently read 895 slides from 35 donors, were analysed to understand how reader technique contributes to discrepancy in measurements of parasite density over a wide range of densities. RESULTS: Among these 35 donations, standard deviations ranged from 30% to 250% of the mean parasite density and the percent discrepancy was inversely correlated with the mean parasite density. The number of white blood cells indexed and whether parasites were counted in the thick film or thin film were shown to significantly contribute to discrepancy amongst microscopists. CONCLUSION: Errors in microscopy measurements are not widely appreciated or addressed but have serious consequences for efficacy trials, including possibly abandoning promising vaccine candidates.

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PubMed2006

Production and validation of durable, high quality standardized malaria microscopy slides for teaching, testing and quality assurance during an era of declining diagnostic proficiency.

BACKGROUND: Sets of Giemsa-stained, blood smear slides with systematically verified composite diagnoses would contribute substantially to development of externally validated quality assurance systems for the microscopic diagnosis of malaria. METHODS: whole blood from Plasmodium-positive donors in Cambodia and Indonesia and individuals with no history of risk for malaria was collected. Using standard operating procedures, technicians prepared Giemsa-stained thick and thin smears from each donor. One slide from each of the first 35 donations was distributed to each of 28 individuals acknowledged by reputation as having expertise in the microscopic diagnosis of malaria. These reference readers recorded presence or absence of Plasmodium species and parasite density. A composite diagnosis for each donation was determined based on microscopic findings and species-specific small subunit ribosomal RNA (ssrRNA) DNA polymerase chain reaction (PCR) amplification. RESULTS: More than 12,000 slides were generated from 124 donations. Reference readers correctly identified presence of parasites on 85% of slides with densities <100 parasites/microl, which improved to 100% for densities >350 parasites/microl. Percentages of agreement with composite diagnoses were highest for Plasmodium falciparum (99%), followed by Plasmodium vivax (86%). CONCLUSION: Herein, a standardized method for producing large numbers of consistently high quality, durable Giemsa-stained blood smears and validating composite diagnoses for the purpose of creating a malaria slide repository in support of initiatives to improve training and competency assessment amidst a background of variability in diagnosis is described.

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PubMed2002

The first reported cases of canine schistosomiasis mekongi in Cambodia.

We have been conducting surveys of schistosomiasis mekongi along the Mekong river in Cambodia since 1997. We attempted to detect canine schistosome infection during the survey in 2000 because dogs were reported to be natural reservoirs of the Mekong schistosome in Lao PDR. A total of 28 canine fecal samples were collected in Kbal Chuor village, Kratie Province and examined for schistosome eggs. One specimen had schistosome eggs (positive rate = 3.6%; egg density = 100/gram stool), which showed characteristics of Schistosoma mekongi. During the 2001 survey, one out of 310 canine stool samples was positive for schistosome eggs (positive rate = 0.32%; egg density = 3,456/gram stool). These are the first confirmed cases of canine schistosomiasis mekongi in Cambodia, which suggests that dogs are animal reservoirs of S. mekongi in the survey area. We further tried to detect S. mekongi in cows, water buffalos, pigs,horses, and field rats in five villages in Kratie Province; no schistosome egg was found in the stools of these animals.

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