IMPLICATIONS OF ASYMPTOMATIC PLASMODIUM FALCIPARUM INFECTIONS FOR FUTURE SYMPTOMATIC MALARIA INFECTION AND ONWARD TRANSMISSION IN WESTERN KENYA

Despite efforts to reduce the malaria burden in high transmission areas like Western Kenya, malaria has persisted, making it important to identify remaining malaria reservoirs. Asymptomatic infections could be sustaining transmission, but their role as a reservoir has not been quantified. Furthermore, the relationship between asymptomatic malaria and future symptomatic infection is poorly understood. Using a 29-month cohort of 268 participants residing in Western Kenya, this dissertation aimed to (1A) investigate the hazard of symptomatic P. falciparum when exposed to asymptomatic malaria versus no infection; (1B) establish the odds of symptomatic infection when exposed to new compared to previously acquired infections; and (2) estimate the relative contributions of asymptomatic and symptomatic human infections to successful onward mosquito transmission events. With a frailty Cox model, aim 1A found that infection with asymptomatic malaria compared to being uninfected greatly increased the short-term, 1-month hazard of symptomatic malaria [hazard ratio: 2.61, 95% CI: 2.05 to 3.33], regardless of parasite density or participant age, but the association weakened as the follow-up period was expanded. Next, using amplicon deep sequencing to determine genetically distinct malaria infections (haplotypes) acquired over time, aim 1B identified that, compared to infections with only recurrent haplotypes, incident infections with only new haplotypes had higher odds of symptomatic malaria [odds ratio (OR): 3.24, 95% CI: 1.20 to 8.78] but infections with both new and recurrent haplotypes had comparable odds of symptomatic malaria [OR: 0.64, 95% CI: 0.15 to 2.65]. Using amplicon deep sequencing of human and mosquito samples as well as probabilistic modelling, aim 2 observed that, compared with symptomatic infections, asymptomatic infections more than doubled the odds of transmission to a mosquito [OR 2.66, 95% CI: 2.05 to 3.47] and were the likely source of 94.6% (95% CI: 93.1 to 95.8%) of mosquito infections. These findings indicate that asymptomatic infections increase the 1-month hazard of symptomatic malaria, are more common in incident infections with previously seen haplotypes, and are major contributors to mosquito infections. Taken together, this research provides a rationale to include asymptomatic infections as a part of malaria reduction interventions in high transmission regions.Doctor of Philosoph

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Risk Categorization Using New American College of Cardiology/American Heart Association Guidelines for Cholesterol Management and Its Relation to Alirocumab Treatment Following Acute Coronary Syndromes

10.1161/CIRCULATIONAHA.119.042551CIRCULATION140191578-158

Effect of Alirocumab on Mortality After Acute Coronary Syndromes An Analysis of the ODYSSEY OUTCOMES Randomized Clinical Trial

10.1161/CIRCULATIONAHA.118.038840CIRCULATION1402103-11

Effects of alirocumab on cardiovascular and metabolic outcomes after acute coronary syndrome in patients with or without diabetes: a prespecified analysis of the ODYSSEY OUTCOMES randomised controlled trial

Background After acute coronary syndrome, diabetes conveys an excess risk of ischaemic cardiovascular events. A reduction in mean LDL cholesterol to 1.4-1.8 mmol/L with ezetimibe or statins reduces cardiovascular events in patients with an acute coronary syndrome and diabetes. However, the efficacy and safety of further reduction in LDL cholesterol with an inhibitor of proprotein convertase subtilisin/kexin type 9 (PCSK9) after acute coronary syndrome is unknown. We aimed to explore this issue in a prespecified analysis of the ODYSSEY OUTCOMES trial of the PCSK9 inhibitor alirocumab, assessing its effects on cardiovascular outcomes by baseline glycaemic status, while also assessing its effects on glycaemic measures including risk of new-onset diabetes