title: The dynamics of measles in sub-Saharan Africa.
abstract: Although vaccination has almost eliminated measles in parts of the world, the disease remains a major killer in some high birth rate countries of the Sahel. On the basis of measles dynamics for industrialized countries, high birth rate regions should experience regular annual epidemics. Here, however, we show that measles epidemics in Niger are highly episodic, particularly in the capital Niamey. Models demonstrate that this variability arises from powerful seasonality in transmission-generating high amplitude epidemics-within the chaotic domain of deterministic dynamics. In practice, this leads to frequent stochastic fadeouts, interspersed with irregular, large epidemics. A metapopulation model illustrates how increased vaccine coverage, but still below the local elimination threshold, could lead to increasingly variable major outbreaks in highly seasonally forced contexts. Such erratic dynamics emphasize the importance both of control strategies that address build-up of susceptible individuals and efforts to mitigate the impact of large outbreaks when they occur.
authors.affiliation: Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. mferrari@psu.edu
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ferrari
authors.forename: Rebecca F
authors.initials: RF
authors.lastname: Grais
authors.forename: Nita
authors.initials: N
authors.lastname: Bharti
authors.forename: Andrew J K
authors.initials: AJ
authors.lastname: Conlan
authors.forename: Ottar N
authors.initials: ON
authors.lastname: Bjørnstad
authors.forename: Lara J
authors.initials: LJ
authors.lastname: Wolfson
authors.forename: Philippe J
authors.initials: PJ
authors.lastname: Guerin
authors.forename: Ali
authors.initials: A
authors.lastname: Djibo
authors.forename: Bryan T
authors.initials: BT
authors.lastname: Grenfell
mesh_terms: D004196:Disease Outbreaks / Q000517:prevention & control; D006801:Humans; D008457:Measles / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission* / Q000821:virology; D008458:Measles Vaccine / Q000008:administration & dosage / Q000276:immunology; D009548:Niger / Q000453:epidemiology; D011891:Rain; D012621:Seasons; D013269:Stochastic Processes; D014611:Vaccination
chemical_list: D008458:Measles Vaccine