Serotype cycles in cholera dynamics

Proc Biol Sci. 2006 Nov 22;273(1603):2879-86. doi: 10.1098/rspb.2006.3668.

Abstract

Interest in understanding strain diversity and its impact on disease dynamics has grown over the past decade. Theoretical disease models of several co-circulating strains indicate that incomplete cross-immunity generates conditions for strain-cycling behaviour at the population level. However, there have been no quantitative analyses of disease time-series that are clear examples of theoretically expected strain cycling. Here, we analyse a 40-year (1966-2005) cholera time-series from Bangladesh to determine whether patterns evident in these data are compatible with serotype-cycling behaviour. A mathematical two-serotype model is capable of explaining the oscillations in case patterns when cross-immunity between the two serotypes, Inaba and Ogawa, is high. Further support that cholera's serotype-cycling arises from population-level immunity patterns is provided by calculations of time-varying effective reproductive rates. These results shed light on historically observed serotype dominance shifts and have important implications for cholera early warning systems.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bangladesh / epidemiology
  • Cholera / epidemiology
  • Cholera / immunology
  • Cholera / microbiology*
  • Humans
  • Models, Immunological
  • Periodicity*
  • Serotyping
  • Vibrio cholerae / classification*
  • Vibrio cholerae / growth & development
  • Vibrio cholerae / immunology