1 / 11

GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

Project : Long-term epidemiology of Meningococcal Meningitis in the African belt: dynamics and impact of vaccination. Spatio-temporal dynamics (spread, persistence, periodicity), Comparative approach, impact of vaccination. Hélène Broutin, PhD

kerri
Download Presentation

GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Project :Long-term epidemiology of Meningococcal Meningitis in the African belt: dynamics and impact of vaccination Spatio-temporal dynamics (spread, persistence, periodicity), Comparative approach, impact of vaccination Hélène Broutin, PhD Post-doctoral researcher (Supervisor: Dr Mark A. Miller) Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

  2. Questions and goals … Better mechanistic understanding of the epidemiology of MM during recent decades(emergence, diffusion, persistence) • Idea = studying the past (long time series) and comparing dynamics in order to: • - detect global patterns vs specialty • understand the impact of vaccination • be able to suggest adapted vaccination strategies • For which population size does the disease persist in time ? • Can we identify sources of infection (does a same locality or district constantly suffer first cases of an epidemic ?) • Do we observe similar routes of transmission of the disease in all countries ? • Do we observe synchrony of epidemics between countries ? Do we observe regular waves of cases ? GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

  3. Concepts when Ecology meets Epidemiology… = POPULATION of POPULATIONS CONNECTED BY MIGRATIONS Epidemiology Metapopulation => POPULATION SIZE Critical Community Size(CCS) Ecology PERSISTENCE IMPACT of VACCINATION ? => POPULATION FLUX concept cities /villages SPREAD

  4. Concepts when Ecology meets Epidemiology… • PERSISTANCE : Critical Community Size (CCS) = • the minimal population size below which a disease cannot persist in a susceptible population without external input(s) • [Bartlett M.S., 1957; Black F.L., 1966; Anderson R.M. & May R.M., 1991; Grenfell B.T. & Harwood J., 1997] analyses of time-period of disease extinction (period with no new cases in a locality) in relation with the population size • DIFFUSION : concept cities / villages= diseases spread from big cities to villages • [Anderson R.M. & May R.M, 1991; Grenfell B.T. & Bolker B.M., 1998] Cases time series analyses between localities

  5. Concepts when Ecology meets Epidemiology… Species maintain Population dynamics(Extinction-recolonization concept) extinction risk for the species

  6. Concepts when Ecology meets Epidemiology… Population dynamicsand Epidemiology(Periodicities - synchronism) Best control Disease persistence These questions are also highly relevant in a global control perspective

  7. Spatio-temporal dynamics of MM in Africa • Periodicity / synchrony GLOBAL –SCALE NATIONAL SCALE(inter-district) Mali LOCAL–SCALE (intra – district) Sikasso District Not only considered epidemics periods (e.g.1994 and 1996) but also inter-epidemics (i.e. 1993 to 1996) to make the link between epidemics) Persistence / Diffusion in relation with population size : can we detect sources of infection ? GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

  8. Illustrations … A) B) Figure extracted from Broutin H, Mantilla-Breniers N. and P. Rohani , Ecology of infectious disease:an example with two vaccine-preventable infectious diseases. Chapt 12 In ‘Encyclopediae of infectious diseases”, in press GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

  9. Different steps … Data Data analyses • - local persistence of the disease in a long-term • local to global diffusion patterns of MM • comparison between countries Detailed and long epidemiological time series : Weekly, by district • - spatial and temporal persistence of serotype in population • periodicity and route of transmission of different serotypes? • quantifying lags between serotypes dynamics Genetics data (serotype) Vaccination data - impact of vaccination on these dynamics ALL THESE analyses will allow a BETTER comprehension in order to be able to Model dynamics of the disease GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

  10. Integration of all components … Population size Genotype Vaccine status Climate Limits / questions Last of immunity ? Proportion of asymptomatic carrier? GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

  11. Collaboration with Dr MP. Préziosi from the WHO (Vaccine Program Initiative) • Dr Pejman Rohani, University of Georgia, Athens, GA, USA. • Availability of detailed data: on MM cases, vaccination and serotype, weekly data, for different countries…. Thank you for your attention GEO Meningitis Environmental Risk Consultative Meeting, 26-27 sept 2007, WHO, Geneva

More Related