Transmissibility of cholera: In vivo-formed biofilms and their relationship to infectivity and persistence in the environment

Shah M. Faruque, Kuntal Biswas, S. M. Nashir Udden, Qazi Shafi Ahmad, David A. Sack, G. Balakrish Nair

Research output: Contribution to journalArticlepeer-review

255 Scopus citations


The factors that enhance the waterborne spread of bacterial epidemics and sustain the epidemic strain in nature are unclear. Although the epidemic diarrheal disease cholera is known to be transmitted by water contaminated with pathogenic Vibrio cholerae, routine isolation of pathogenic strains from aquatic environments is challenging. Here, we show that conditionally viable environmental cells (CVEC) of pathogenic V. cholerae that resist cultivation by conventional techniques exist in surface water as aggregates (biofilms) of partially dormant cells. Such CVEC can be recovered as fully virulent bacteria by inoculating the water into rabbit intestines. Furthermore, when V. cholerae shed in stools of cholera patients are inoculated in environmental water samples in the laboratory, the cells exhibit characteristics similar to CVEC, suggesting that CVEC are the infectious form of V. cholerae in water and that CVEC in nature may have been derived from human cholera stools. We also observed that stools from cholera patients contain a heterogenous mixture of biofilm-like aggregates and free-swimming planktonic cells of V. cholerae. Estimation of the relative infectivity of these different forms of V. cholerae cells suggested that the enhanced infectivity of V. cholerae shed in human stools is largely due to the presence of clumps of cells that disperse in vivo, providing a high dose of the pathogen. The results of this study support a model of cholera transmission in which in vivo-formed biofilms contribute to enhanced infectivity and environmental persistence of pathogenic V. cholerae.

Original languageEnglish (US)
Pages (from-to)6350-6355
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - Apr 18 2006
Externally publishedYes


  • Cholera epidemic
  • Conditionally viable environmental cells
  • Vibrio cholerae
  • Waterborne disease

ASJC Scopus subject areas

  • General


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