Facts about plague epidemic, 1994

The letter by P. T. Patel and H. P. Pandya (Curr. Sci., 1998, 75, 415) provides vital new information on one of the major lacunae in the sequence of events that led to the unfortunate episode of out- break of pneumonic plague in Surat in 1994.

Yersinia pestis can be easily grown and identified in any standard microbiology laboratory. Therefore it is quite reasonable to accept that Patel and Pandya had indeed isolated and characterized Y. pestis from the sputum specimens of several persons with pneumonic symptoms, including the very first case admitted to the New Civil Hospital. Moreover, as stated by them this crucial piece of information corroborates with the report of the Technical Advisory Committee (TAC) which mentioned that stored cultures and sputum specimens were indeed available for investigation1. Though microbiologists do not usually store raw specimens, they do often store cultures of isolates according to text book procedures. Thus, Patel and Pandya do have a point about the veracity of the stored sputum samples: it is not difficult to get details on this issue, but it does not seem to me to be very important now. The TAC found the stored cultures to be contaminated and were not pure cultures and it was subculturing of these contaminated cultures which resulted in isolating Y. pestis1. In addition, the boldness with which the government officials had declared that the cause of the outbreak was plague did suggest that they were privy to information that was not available to the public or even to researchers in the field of microbiology in the country.

This new information raises more questions than it answers. Patel and Pandya say that their department had cultured and reported Y. pestis. I have followed the events in great detail2. The TAC, the Expert Committee appointed by the Gujarat state government and the WHO International Plague Investigative Team were clear that the then available evidence for pneumonic plague was only presumptive, being clinical and serological; that was not sufficient to confirm the cause as Y. pestis infection in the absence of identification by culture2. I too had been skeptical about the diagnosis of plague itself, mainly because the microbiologists in Surat apparently had not cultured this organism which is very easy to isolate and characterize. Therefore alternate hypotheses were mooted and one positive outcome was the recognition of melioidosis in India3. The Gujarat Committee had pointed out that the only microbiological evidence for Y. pestis was presence of bipolar staining organisms in sputum smears. The cause of melioidosis is also bipolar staining.

The negative impact of the lack of timely evidence for plague was that the TAC had to unravel the mystery of the cause of the epidemic and it was their conclusive report of the isolation of Y. pestis and the detection of its genetic sequences in necropsy tissues that laid to rest the alternate speculations1. If Patel and Pandya had reported their data to any responsible agency, the TAC would not have been burdened with diagnosis but should have paid more attention to the reasons of the sudden appearance of pneumonic plague in a city, which have not yet been satisfactorily explained. The second reason for my earlier skepticism was the missing epidemiological links such as the lack of previously recognized sylvatic focus in the region, the absence of bubonic plague preceding pneumonic plague and the zero incidence of secondary cases. Since the attention of everyone was diverted from investigating the source of Y. pestis in a unique and unprecedented, exclusively pneumonic, plague outbreak, to the very diagnosis itself, the timely opportunity to ask this most important question was lost. At this point in time I do not want to speculate on the source, but it is not easy to explain it as a natural outbreak. It is very important not to lose sight of this issue, since history has a tendency to repeat itself where people do not learn from it.

I am grateful to Patel and Pandya for their old but new information. They must now give more details about their data. What the dates of their laboratory reports were, how many isolates they had confirmed and to whom they had reported are essential to determine if their crucial observations had been suppressed for some reason by someone. They must also clarify why their findings had not found their way in a journal earlier than now. It is never too late for filling gaps in information, for, Satyamevajayathe.

Report of the Technical Advisory Committee on Plague, New Delhi, 1995.
John, T. J., Lancet, 1995, 346, 765.
Cherian, T., Raghupathy, P. and John, T.J., Lancet, 345, 259.
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