a1 Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
a2 Center for the Study of Complex Systems, University of Michigan, Ann Arbor, MI, USA
a3 Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
Recent much-publicized increases in pertussis case reports in some countries with high vaccine coverage have raised concerns about its current and future control. The ubiquity of this trend, however, remains unexamined. In an attempt to paint a global picture, we used case counts to determine which countries experienced statistically significant trends in incidence over the past two decades and to map changes in incidence during this period. These data reveal that pertussis resurgence is not a universal phenomenon. The heterogeneity in incidence trends, even in countries with superficially similar demography, socioeconomic conditions and vaccination programmes, is striking and requires explanation. In this opinion piece, we review and assess the multifaceted proposed explanations incorporating evolution, population dynamics, and the details of immunization programmes. While we do not solve the riddle that is pertussis epidemiology, we highlight critical aspects that are likely to hold the key to understanding its worldwide epidemiology.
(Received October 16 2012)
(Revised December 10 2012)
(Accepted December 10 2012)
(Online publication January 16 2013)