Quantitative, model-based estimates of variability in the serial interval ofPlasmodium falciparummalaria

Abstract

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. Results: 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. Conclusions: 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.

Estimating spatiotemporally varying malaria reproduction numbers in a near elimination setting

“…The prior for the a parameter determining the shape of the distribution was given a Uniform distribution and bounded, giving an expected time between symptom onset of one case and symptom onset of the case it infects of 29 days (95%CI = 16-300 days, sd = ±7 days), with the lower bound having an expected serial interval of 25 days (95% CI = 16 -299 days, sd = ±4 days) and the upper bound 47 days (95% CI = 16-300 days sd = ±18 days). By comparison the expected values for treated P. falciparum from existing literature range between 33 17 and 49.1 days (95%CI = 33-69) 47 .…”

“…We defined a prior range of possible serial interval distributions for malaria. The serial interval distribution of treated, symptomatic P. falciparum malaria, previously characterised using empirical and model based evidence 47 was adapted to inform the prior distribution for the relationship between time and likelihood of transmission between cases in El Salvador. Two cases imported from West Africa were P. falciparum, however the remainder of cases were P. vivax.…”