The last paragraph of the chapter ‘Resuscitation of VBNC, outbreak and global spread of cholera’ in my book “The systemic practice of misinterpretation of scientific data” is reproduced below
In short, Dr. Colwell’s group has put forward three theories
1. resuscitation of VBNC is responsible for the seasonal outbreak of cholera in endemic areas
2. the aquatic environment plays an important role in the ecology of V. cholerae, and
3. autochthonous V. cholerae is responsible for the presence of pandemic strains across the world.
However, out of the three theories, both the first and the third theories remain scientifically questionable.
The book was published on September 2010, one month before the cholera outbreak in Haiti. The hypothesis that autochthonous (indigenous) V. cholerae is responsible for the outbreak of cholera in places distant from their point of origin was not convincing to me on the basis of the cholera outbreak (seventh pandemic) in Peru in 1991.
The seventh pandemic cholera, caused by V. cholerae O1 El Tor, originated in Indonesia in 1961 and later spread to most of Asia and Africa. In 1991, it reached Peru and from there, it spread to many countries of Latin America. Since Latin America was free of cholera for nearly a century, the scientists were unsure of how the organism reached Peru. There were many speculations.
1. Non-toxigenic V. cholerae already present in the aquatic environment of Peru acquired virulence through recombination
2. Toxigenic V. cholerae was already present in coastal waters of Peru
3. Ocean currents carried the organism from endemic areas to Peru
4. The organism was imported to Peru from endemic areas either by travelers or other carriers
Whereas the first two speculations emphasize the importance of autochthonous V. cholerae in the outbreak of cholera, the third one suggests that the organism can be carried to distant places through sea without the involvement of humans. Only the last speculation is based on human-associated factors.
One of the arguments against the proposal that autochthonous toxigenic V. cholerae is responsible for cholera outbreak in Peru is the failure to detect the organism in Latin America before the outbreak. Moreover, there were no reports of cholera in Latin America for nearly a century. Why some cholera researchers are adamant that an outbreak can occur only through the activation of autochthonous V. cholerae? Even if it has to be carried, why it has to occur through sea with the help of ocean currents? If cholera can be carried from Dominican Republic to New York (1), from Thailand to Maryland (2) or from Calcutta to Guinea (West Africa) (3) with the help of humans or other carriers, why it can’t reach Peru from distant locations through carriers? Similarly, why it can’t reach Haiti from Nepal through Nepalese peacekeepers especially since a cholera outbreak had occurred in Nepal just two weeks before they travelled to Haiti?
Autochthonous V. cholerae theory could not be ruled out completely in 1991 because researchers were not able to pinpoint an exact carrier that could have caused the cholera outbreak in Peru. However, with the outbreak of cholera in Haiti in 2010, the above theory may not hold valid. It will be much more difficult for researchers to further support the questionable ‘autochthonous theory’ or ‘ocean current theory’.
Next- ‘Ocean current hypothesis’ and Vasco da Gamas of the microbial world
3. Sharma et al. 1998. Molecular evidence that a distinct Vibrio cholerae O1 biotype El Tor strain in Calcutta may have spread to the African continent. Journal of Clinical Microbiology, 36 (3): 843-844
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