Was toxigenic V. cholerae present in the aquatic environment of Peru before the outbreak?

Even though cholera outbreak in Peru occurred in January 1991 as per the official records, it was argued that the organism was present in the aquatic environment much earlier. (Read the article “New insights on the emergence of cholera in Latin America during 1991: The Peruvian experience”)

In this article, medical records obtained from different hospitals in Peru over the five-month period (September–January) during 1989/1990 and 1990/1991 were reviewed. It was noticed that seven patients attended emergency rooms for clinical signs of acute watery diarrhea and dehydration between October 1990 and January 1991. i.e. before the official record of cholera outbreak. These patients were residing in different geographical locations separated by about 1000 kilometers. All the patients were given intravenous fluids and none of them died and were discharged after a short period of hospitalization. Based on the clinical signs of these medical records, authors argued that these cases were caused by V. cholerae and that toxigenic V. cholerae was present in the aquatic environment at least 4 months prior to the recognized onset of cholera epidemic. They also argued that since the patients were located in different geographical areas separated by about 1000 kilometers, the epidemic did not start from a single location, but rather from multiple locations.

           

However, the assumption that cholera started much earlier was solely based on clinical symptoms of patients and those medical records lacked microbiological confirmation of the cause of watery diarrhea as admitted by the authors. Since a number of organisms can cause watery diarrhea (not only bacteria, but also viruses, parasites, food poisoning, chemicals etc.), there is no evidence that the illness was indeed caused by V. cholerae. Moreover, they were isolated cases and there were no reports of the disease spreading to other persons. Similarly, all patients were discharged after a short hospitalization and did not have any complications. On the other hand, once the cholera epidemic began, the disease spread quickly and resulted in a number of deaths.

           

Thus, based on medical records of clinical cases of watery diarrhea alone, the authors ‘discovered’ that

1. cholera started in Peru at least 4 months before the official recorded cases

2. toxigenic V.cholerae was present in the aquatic environment of Peru before the outbreak

3. cholera outbreak started from multiple locations separated by about 1000 kilometers thus rejecting the single entry hypothesis.

Again, this finding was cited in the subsequent articles and reviews as the evidence for ‘autochthonous V. cholerae theory’.

Can researchers prove the existence of organism in Haiti before October 2010? If they can get the medical records from Haiti which shows at least a clinical case of acute watery diarrhea a few months before October 2010, they can ‘prove’ the autochthonous V. cholerae theory. And, with more than one clinical cases recorded in different geographical areas, they can also reject the single entry hypothesis!!

Next- More questions on Seas et al. (2000)