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T. Alex Perkins

Publications and source records attributed to T. Alex Perkins.

2 recordsLinked to original sources

Quantitative, model-based estimates of variability in the serial interval of Plasmodium falciparum malaria

Background: The serial interval is a fundamentally important quantity in infectious disease epidemiology that has numerous applications to inferring patterns of transmission from case data. Many of these applications are apropos to efforts to eliminate Plasmodium falciparum (Pf) malaria from locations throughout the world, yet the serial interval for this disease is poorly understood quantitatively.\n\nResults: To obtain a quantitative estimate of the serial interval for Pf malaria, we took the sum of components of the Pf malaria transmission cycle based on a combination of mathematical models and empirical data. During this process, we identified a number of factors that account for substantial variability in the serial interval across different contexts. Treatment with antimalarial drugs roughly halves the serial interval, seasonality results in different serial intervals at different points in the transmission season, and variability in within-host dynamics results in many individuals whose serial intervals do not follow average behavior.\n\nConclusions: These results have important implications for epidemiological applications that rely on quantitative estimates of the serial interval of Pf malaria and other diseases characterized by prolonged infections and complex ecological drivers.

Epidemiology

Big city, small world: Density, contact rates, and transmission of dengue across Pakistan.

Macroscopic descriptions of populations commonly assume that encounters between individuals are well mixed; i.e., each individual has an equal chance of coming into contact with any other individual. Relaxing this assumption can be challenging though, due to the difficulty of acquiring detailed knowledge about the non-random nature of encounters. Here, we fitted a mathematical model of dengue virus transmission to spatial time series data from Pakistan and compared maximum-likelihood estimates of \"mixing parameters\" when disaggregating data across an urban-rural gradient. We show that dynamics across this gradient are subject not only to differing transmission intensities but also to differing strengths of nonlinearity due to differences in mixing. We furthermore show that neglecting spatial variation in mixing can lead to substantial underestimates of the level of effort needed to control a pathogen with vaccines or other control efforts. We complement this analysis with relevant contemporary environmental drivers of dengue.

Ecology