RT Journal Article
SR Electronic
T1 An antigenic diversification threshold for falciparum malaria transmission at high endemicity
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.01.01.892406
DO 10.1101/2020.01.01.892406
A1 Qixin He
A1 Mercedes Pascual
YR 2020
UL http://biorxiv.org/content/early/2020/05/16/2020.01.01.892406.abstract
AB In malaria and several other important infectious diseases, high prevalence occurs concomitantly with incomplete immunity. This apparent paradox poses major challenges to malaria elimination in highly endemic regions, where asymptomatic Plasmodium falciparum infections are present across all age classes creating a large reservoir that maintains transmission. This reservoir is in turn enabled by extreme antigenic diversity of the parasite and turnover of new variants. We present here the concept of a threshold in local pathogen diversification that defines a sharp transition in transmission intensity below which new antigen-encoding genes generated by either recombination or migration cannot establish. Transmission still occurs below this threshold, but diversity of these genes can neither accumulate nor recover from interventions that further reduce it. An analytical expectation for this threshold is derived and compared to numerical results from a stochastic individual-based model of malaria transmission that incorporates the major antigen-encoding multigene family known as var. This threshold we call Rdiv; it is complementary to the one defined by the classic basic reproductive number of infectious diseases, R0, which does not easily apply under large and dynamic strain diversity. This new threshold concept can be exploited for effective malaria control and applied more broadly to other pathogens with large multilocus antigenic diversity.Competing Interest StatementThe authors have declared no competing interest.