KOLKATA: Seventy-five years after Robert Koch discovered the cholera bacteria in 1884, a Bengali scientist had unearthed the fact that it was a toxin produced by the bacteria that triggered loss of fluid from the body and caused thickening of blood, eventually leading to death.

Sambhu Nath De, researcher and former director of pathology at the Calcutta Medical College, had carried out the path-breaking work at Kolkata’s Bose Institute under severe constraints and with meagre resources, eventually establishing the existence of the toxin in 1959. The oral rehydration therapy which has saved millions of cholera patients over the years is believed to be a direct outcome of his work.

Even though his discovery was perhaps no less significant than that of Ronald Ross’ at the turn of the century, De remained largely unrecognized in India till his death in 1985. Barring a lecture in Delhi, his centenary year, too, has gone unnoticed. His family wants Calcutta University to introduce an annual lecture in his memory.

“His contribution was hailed by the international science community years after the discovery. In the late Sixties, researchers abroad started referring to his work. In 1978, the Nobel Foundation sought him out and invited him to Nobel Symposium on cholera where he delivered a lecture. In 1990, Science Today magazine published a special issue on him. But, his work was never given due importance in India. In fact, few even referred to it. He didn’t bother about it, though. He was happy with his experiments,” said Shyamal De, his son.

Moved by frequent cholera epidemics in the 1940s, De had started experimenting on the pathogenesis of cholera even as he was researching on pulmonary oedema at the University College Hospital Medical School in London. He returned to Kolkata in 1949 and carried on his work, focusing on the changes in the kidneys in cholera cases. He published a series of papers between 1950 and 1955. But the course of his experiments took a turn after he observed the ‘toxic appearance of cholera patients in Kolkata’ which suggested that the disease was primarily caused by organisms that multiplied in the lumen of the gut, died, underwent autolysis and released a toxin. It was the toxin that acted on the system, De surmised.

He went on to establish his theory using the ‘loop method’ in rabbits. The local science community refused to accept it and scientists abroad were skeptical. “But my father was confident that he had made a breakthrough. Almost every night he would travel to the physical and protein chemistry laboratory of Bose Institute where he stored his apparatus and experimented on rabbits. Research facilities for isolation of the toxin were not available at Medical College where he worked. He would observe the results of his experiments for hours and then take notes,” said Shyamal De.

He did receive International recognition for this work including the nomination for the Nobel Prize by none other than Nobel laureate Joshua Lederberg.

Veteran scientist Bikash Sinha describes him as one of the unsung heroes of Bengal who never got his due.

