Thanks to Dr. Ralph Frerichs for sending the link to this important article in the French Association for Scientific Information: Interview with Renaud Piarroux. The Google translation, with my bolding, and a comment:
SPS: What are the links between natural disasters and infectious diseases?
Renaud Piarroux: It depends on the type of natural disaster. In a study we conducted in 2005, we were surprised to find almost no epidemic in the immediate aftermath (first three months) of more than 600 geophysical disasters (earthquakes, volcanic eruptions, tsunamis), nor in the scientific literature, nor in situation reports written by field workers. This is probably due to the fact that the victims of these types of disasters receive prompt and specific assistance to prevent major epidemic risks (vaccination, securing access to water). This rule is not absolute, however, and epidemics of respiratory infections or scabies have occurred in some cases, favored by cold and promiscuity.
The case of meteorological disasters is different because drought or flood events can directly affect the life cycle of various pathogens and disease vectors. In addition, affected areas are generally larger and aid is both more limited and more diluted.
The case of Haiti does not derogate from the rule of scarcity of epidemics after an earthquake. Indeed, the cholera epidemic occurred after nine months, it started in an area not affected by the earthquake and was caused by a cause independent of the earthquake. Finally, IDP camps were less heavily affected than slums and rural areas.
Science has been used both as a pretext to disguise a heavy responsibility, but it has also been a tool that has finally established this responsibility. What lesson do you learn from this dramatic story?
The hoax has been a double-edged sword. Disorienting scientists and the public by biasing status reports and mobilizing certain experts to remove suspicion has almost succeeded in obscuring the responsibility of peacekeepers. But paradoxically, it probably helped to consolidate the proof of their responsibility.
Indeed, it would have been more difficult to obtain isolated strains in Nepal in the summer of 2010 if Nepalese biologists had thought that it would confirm the responsibility of the soldiers of their country. However, at the time of the study, the mystification helping, the dominant idea was that the Nepalese peacekeepers had nothing to do with the epidemic.
Once the absolute identity was established between one of the Nepalese strains and the Haitian strain, the link between the peacekeepers and the epidemic became clear. The approach is identical to that of the scientific police comparing the DNA of a suspect to that found on the crime scene. But here, in the absence of a judicial inquiry, the experimentation was conducted as research, just to establish the truth. Note the exemplary attitude of Nepali biologists who have assumed this very embarrassing result for their own country.
More generally, this story shows how difficult it is to hide anything from an informed audience. Here some scenes have been filmed, others have been photographed, messages have been exhumed by Wikileaks or under United States law, and genomic strains and sequences that can be used as evidence have been circulating from one country to another.
Has it settled the more general controversy over the possible environmental cause in a cholera outbreak?
In theory, demonstrating that an epidemic is of imported origin does not prevent elsewhere that a cholera outbreak is the result of local emergence. However, in recent years, the analysis of thousands of genomes of strains collected during epidemics has established a direct relationship between all epidemics. Thus, the two epidemic waves in Latin America (that of Haiti and that which hit Peru in 1991) result from intercontinental introductions of strains of Vibrio cholerae circulating in the world. Similarly, the epidemic waves that have affected Africa for fifty years are due to the importation of cholera from Asian foci.
What remains to be verified is the ability of a strain - initially imported - to establish itself sustainably in certain aquatic environments (eg brackish estuarine waters) and then to provoke local re-emergence of cholera. We will be able to settle this question, which is still debated if the current trend continues.
Indeed, since the end of January 2019, no case of cholera has been confirmed in Haiti despite a sustained effort to test the maximum number of diarrheal patients (there are 96 negative results in a row). It's time to look for the strain in the environment. If, in the coming months, we still do not identify sporadic cases, the hypothesis of a rooting of the strain in the environment can be ruled out.
Of course, in case of new epidemic, it will be necessary to verify, by DNA sequencing, whether it is the same strain or another, imported from an endemic area.
Finally, if it turns out that Haiti's epidemic is definitely over, it would open up huge hopes for the fight against cholera all over the world.
It has been almost exactly nine years since the first cases were reported. If cholera is truly over in Haiti, it will be thanks to the patient efforts of Dr. Renaud Piarroux and the government and people of Haiti.
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