Ranganathan in his biography, stated that by the end of 1918, it was definitely known that tuberculosis had set in. In the more complete biography, Robert Kanigel, also lays emphasis on tuberculosis as being the cause of Ramanujan's prolonged, terminal illness. A systematic study of the details led Prof. Robert Rankin, in 1984, to point out that Ramanujan's illness was not properly diagnosed and tuberculosis was not the cause of his death. It is a fact that the warmer climates of Madras and its surroundings did not show any marked improvement in his health after his return. On the contrary, his condition further deteriorated and towards the end, he was reduced to 'only skin and bone', as described by his wife.

Dr. D.A.B. Young, in 1994, researched into Ramanujan's illness and this 'latest detective work' gives us a better insight into the health of Ramanujan. We give here a brief summary of this medical biography or medicography:

Ramanujan came to the city of Madras, in 1906, and joined the Pachaiyappa's College to study in the F.A. class again. But, a few months later, he fell ill with dysentery and had to return to Kumbakonam for a period of about three months. It is conjectured, after sieving through all the information, that Ramanujan's dysentery was caused by amoebiasis, a tropical infection widespread in the metropolitan cities of India.

Amoebiasis, unless adequately treated, is a permanent infection, although many patients may go for long periods with no overt signs of the disease. Relapses occur when the host-parasite relationship is disturbed. Ramanujan experienced such a relapse, I believe, in 1909 when according to his friend R.R. Ayyar ["Ramanujan: The Man and the Mathematician", S.R. Ranganathan, Asia Publishing House, 1967]:

Ramanujan, who was living in [Madras], became seriously ill ... As a patient … he was obstinate and would not drink hot water and insisted on eating grapes which were sour and bad for him. [The doctor] after examining him, asked me to send him to his parents as his condition required constant nursing.

How ill Ramanujan felt at this time is indicated by his giving his host for safe keeping the two large notebooks kept with him all the time and in which he had been recording his mathematical results; the same notebooks that are now famous as a major legacy of his genius.

Later the same year (1909), while still at home with his family, he developed a hydrocele, which was operated on in January 1910 ["The Man Who Knew Infinity: A Life of the Genius Ramanujan", Robert Kanigel, Charles Scribner's Sons, New York (1991); Indian edition published by Rupa & Co.(1994).]. … Dr. Shaw's suspicion that the operation was the excision of a malignant growth, depending as it must have done on Ramanujan's exact description of the lesion, certainly favours the explanation of a scrotal amoeboma rather than a hydrocele.