Environmental Reservoir of Vibrio cholerae The Causative Agent of Choleraa

Abstract

BACKGROUNDUntil the late 1970s and early 1980s, Vibrio cholerae was believed to be highly host-adapted and incapable of surviving longer than a few hours or days outside the human intestine. This view, enunciated by Felsenfeld,' was that "some authors claimed that cholera vibrios may survive in water, particularly seawater, for as long as 2 months. This is, however, scarcely possible under natural conditions, if reinfection of the water does not take place." This perspective of cholera ecology dominated the literature since the organism was first identified by Robert Koch in 1884.2 For V. chohae the term ''survival" had been viewed to reflect a high degree of host-adaptation, ea., "cholera vibrios" being able to exist for only very short periods of time outside the human intestine. But Koch's speculation that multiplication takes place in river water, without any assistance, has proven to be prescient, since the most recent data show that toxigenic V. cholerae 01 exist for long periods in laboratory microcosm water.' In fact, the evidence accumulated over the ast decade shows that V. chohae is an tochthonous nature of V. choferae 0 1 is an important factor in the epidemiology of cholera, significantly so in endemic areas. Thus, the very early studies of V. cholerue, prior to 1970, were aimed at identifjring environmental conditions associated with unusual delays in the inevitable "death" of the "cholera vibrios," in order to establish the length of time after which an environment could be considered cholera-free, unless recontaminated with infected stool. The remarkable discoveries of the past decade have revealed the existence of the dormant or somnabulant ( i e . , viable but non-culturable) state into which V. cholerae 01 and V. cholerae non-01 enter in response to nutrient autochthonous inhabitant of brac L 'sh water and estuarine ~ystems.~ The aua The work reported here was supported,

Environmental Surveillance for Toxigenic Vibrio cholerae in Surface Waters of Haiti

“…The association of V. cholerae with zooplankton can protect the bacteria from environmental stresses and low nutrient levels and enhance their distribution in the environment. 7,8,34 The toxigenic V. cholerae detection data from this study are supported by the research results of Alam and others 6 who reported isolating the toxigenic V. cholerae O1 El Tor biotype from three water samples collected between April 2012 and March 2013 in the Ouest Department near the towns of Gressier and Leogane. However, other researchers, using only culture methods, did not isolate or detect toxigenic V. cholerae from water samples collected in July 2012 from 36 aquatic locations in the Ouest and Artibonite Departments.…”

“…The positive associations between DFA-DVC detections and salinity, temperature, and specific conductance are in concordance with the established paradigm of V. cholerae as autochthonous to the aquatic environment. 34 During this study, TCBS agar resulted in a significantly higher percentage of V. cholerae positive isolates compared with CV agar. However, these findings warrant further investigation; there are several brands of TCBS on the market and there are differences in performance between brands.…”

Influence of temperature and rainfall on the evolution of cholera epidemics in Lusaka, Zambia, 2003–2006: analysis of a time series

“…Nevertheless, it has also been shown to resist suboptimal conditions through specific associations of the bacterium with aquatic plants 10 or animals such as oysters, crabs and copepods. [11][12][13][14] As a result, the pathogen can persist for longer periods in aquatic habitats. Weather conditions such as an increase in environmental or sea surface temperatures favour plankton bloom.…”

Genome-wide requirements for Mycobacterium tuberculosis adaptation and survival in macrophages

“…In contrast, a significant number of MTB genes that are essential for growth in macrophages are constitutively expressed. Unlike pathogens with environmental reservoirs like Salmonella typhi or Vibrio cholerae (22,23), MTB never resides outside of the human host and depends exclusively on transmission between humans for its continued survival (1). Constitutive expression of genes required for survival may be a necessary adaptation to a complex lifestyle in the host milieu.…”