Estimates of the changing age-burden of Plasmodium falciparum malaria disease in sub-Saharan Africa

Abstract

Estimating the changing burden of malaria disease remains difficult owing to limitations in health reporting systems. Here, we use a transmission model incorporating acquisition and loss of immunity to capture age-specific patterns of disease at different transmission intensities. The model is fitted to age-stratified data from 23 sites in Africa, and we then produce maps and estimates of disease burden. We estimate that in 2010 there were 252 (95% credible interval: 171–353) million cases of malaria in sub-Saharan Africa that active case finding would detect. However, only 34% (12–86%) of these cases would be observed through passive case detection. We estimate that the proportion of all cases of clinical malaria that are in under-fives varies from above 60% at high transmission to below 20% at low transmission. The focus of some interventions towards young children may need to be reconsidered, and should be informed by the current local transmission intensity.

Assessing the impact of next-generation rapid diagnostic tests on Plasmodium falciparum malaria elimination strategies

“…Onward infectivity to mosquitoes is highest in clinical disease, intermediate in patent asymptomatic infection and lowest in sub-patent infection parameterized by fitting to four earlier mosquito feeding studies 29 . As the model does not explicitly track parasite density, we adapted this structure to capture a wider range of diagnostic sensitivities by using results of the data analysis to define the proportion of infections that are detectable at a given parasite threshold within each of the infected compartments.…”

“…We used a deterministic age-structured population-level transmission model that tracks three infected compartments of the population -clinical disease, patent asymptomatic infection (identifiable by microscopy), and sub-patent (sub-microscopic) asymptomatic infection 29 . Onward infectivity to mosquitoes is highest in clinical disease, intermediate in patent asymptomatic infection and lowest in sub-patent infection parameterized by fitting to four earlier mosquito feeding studies 29 .…”

A combined analysis of immunogenicity, antibody kinetics and vaccine efficacy from phase 2 trials of the RTS,S malaria vaccine

“…We combine this data with a previously published model for the acquisition of clinical immunity [5] to account for reductions in efficacy against clinical malaria due to lower levels of naturally-acquired immunity in vaccinated compared to unvaccinated children. These results from heterogeneous groups in the phase 2 trials will complement the critical analyses from the multi-site phase 3 trial [1,2].…”

Imitation dynamics of vaccine decision-making behaviours based on the game theory

“…Then applying the comparison principle yields 0 ≤Ŝ(t) ≤ S(t + t 1 ) and 0 ≤î(t, a) ≤ i(t + t 1 , a) (18) for (t, a) ∈ R 2 + . Since (1 − η)R 0 > 1, applying Theorem 2.3 again, we see that…”

“…There exists ample theoretical work investigating infectious diseases and very valuable results on the control of epidemic spread have been obtained. In some of the studies [5,16,18,22,29,34] on childhood diseases, one eminent feature is that the transmission rates have salient differences since children have different immunities.…”