University of Georgia, Odum School of Ecology, Athens, Georgia
William B MacLeod
Boston University School of Public Health, Department of Global Health, Boston, United States
Lawrence Mwananyanda
Boston University School of Public Health, Department of Global Health, Boston, United States; Right to Care, Lusaka, Zambia
Donald M Thea
Boston University School of Public Health, Department of Global Health, Boston, United States
Rachel C Pieciak
Boston University School of Public Health, Department of Global Health, Boston, United States
Geoffrey Kwenda
University of Zambia, School of Health Sciences, Department of Biomedical Science, Lusaka, Zambia
Zacharia Mupila
Right to Care, Lusaka, Zambia
Pejman Rohani
University of Georgia, Odum School of Ecology, Athens, Georgia; University of Georgia, Center for the Ecology of Infectious Diseases, Athens, Georgia; University of Georgia, Department of Infectious Diseases, Athens, Georgia
Recent pertussis resurgence in numerous countries may be driven by asymptomatic infections. Most pertussis surveillance studies are cross-sectional and cannot distinguish asymptomatic from pre-symptomatic infections. Longitudinal surveillance could overcome this barrier, providing more information about the true burden of pertussis at the population level. Here we analyze 17,442 nasopharyngeal samples from a longitudinal cohort of 1320 Zambian mother/infant pairs. Our analysis has two elements. First, we demonstrate that the full range of IS481 qPCR CT values provides insight into pertussis epidemiology, showing concordance of low and high CT results over time, within mother/infant pairs, and in relation to symptomatology. Second, we exploit these full-range qPCR data to demonstrate a high incidence of asymptomatic pertussis, including among infants. Our results demonstrate a wider burden of pertussis infection than we anticipated in this population, and expose key limitations of threshold-based interpretation of qPCR results in infectious disease surveillance.
