Asymptomatic Malaria Gametocyte levels in Kenya: An observational survey

Case Western Reserve University, Cleveland OH

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Abstract

? DESCRIPTION (provided by applicant): More than three billion people live with the threat of malaria throughout the world, which results in a significant impact on the economic stability of developing countries and subsequently on the global economy. While improvements in terms of morbidity, mortality, and transmission have been achieved in the past 5 years, malaria parasites continue to evade elimination. Our long term goal is to aid global malaria elimination efforts through improved detection, diagnosis, and treatment. We hypothesize that the issue of ongoing malaria transmission can be addressed through better assessment of total malaria prevalence (overall) and a more accurate determination of gametocyte prevalence (specific). Without this kind of information many elimination efforts will fail. Our multidisciplinary team of malariologist, physicists, and biomedical engineers exploited the magnetic properties of malaria pigment, hemozoin, to develop a device that utilizes magneto-optical detection (MOD) of hemozoin thereby avoiding staining and microscopy-based examination of patient blood. This inexpensive, portable MOD device uses alternating magnetic fields to align hemozoin so that it blocks transmitted light in proportion to parasitemia (R2=0.9997). Laboratory studies of the MOD device have optimized signal to noise ratios to detect parasitemia < 0.00002% (<1 parasitized cells/µL) with a sensitivity of 94% in less than 1 minute. Further, to determine the levels of gametocytemia we will perform quantitative reverse transcription polymerase chain reaction (qRT-PCR) on samples which are positive for malaria by MOD. In accordance with the malERA Consultative Group on Diagnosis and Diagnostics recommendations, we will use our methodology (MOD) to conduct population surveillance for active case detection of very low levels of Plasmodium infection to help identify asymptomatic individuals contributing to malaria transmission. Evaluating large numbers of asymptomatic individuals over time will provide the first opportunity to assess the levels of gametocytes in a large population. In conjunction with clinical malaria prevalence and vector intervention we will be able to more effectively model the potential for ongoing malaria transmission. Therefore, this proposal will provide insights needed to predict the potential for resurgence of malaria transmission in endemic regions, which, ultimately, may lead to improved treatment and eradication efforts.