James Joyce, who wrote of his worsening vision in 1931 that "I deserve all this on account of my many iniquities", was trying to confess that he was suffering from syphilis, according to new evidence uncovered by a Harvard scholar, which could upset current perspectives on the author's life and fiction.

Kevin Birmingham, a lecturer in history and literature at Harvard University, claims in his forthcoming history of Joyce's Ulysses, The Most Dangerous Book, that Joyce was going blind because he was suffering from syphilis – "his eye attacks were recurrent because syphilis advances in waves of bacterial growth and dormancy". The array of symptoms Joyce described in detail to his correspondents, "the abscesses that ravaged his mouth and the large 'boil' on his shoulder", were probably syphilitic, writes Birmingham. "Syphilis 'disabled' his right arm in 1907", and the psychological toll of the disease "likely caused Joyce's periodic fainting spells, his insomnia and his 'nervous collapses'", according to the scholar.

Rumours that Joyce had syphilis were circulating during the author's lifetime, but first hit print in 1975, when a biography of Joyce claimed he had congenital, rather than acquired, syphilis. In 1995, Kathleen Ferris's James Joyce and the Burden of Disease also made the claim – but she "makes a lot of assumptions and counts literary evidence as biographical evidence: if one of Joyce's character's had syphilis, that meant Joyce had syphilis", said Birmingham. Her work was "openly ridiculed" by the medical doctor JB Lyons (who knew Joyce), and the issue "faded away", according to Birmingham, who added that "to this day there are prominent Joyceans who haven't even heard of the debate".

He himself stumbled across the pieces of the jigsaw which led him to his diagnosis while reading of Joyce's symptoms in Richard Ellmann's biography of the author. "There are very few ailments that cause decades of recurrent anterior uveitis (the current term for 'iritis'). Syphilis was by far the most common at the time, and yet Ellmann doesn't even mention the possibility that syphilis caused it," said Birmingham, whose book is published later this week by Head of Zeus, in time for Bloomsday on 16 June, the annual celebration of the day on which Ulysses' protagonist Leopold Bloom wandered the streets of Dublin.

A suitable case for treatment … the drug prescribed to Joyce for his symptoms

The Harvard scholar decided to "turn over every stone" to find out what might have caused Joyce's deteriorating vision, compiling references to every symptom and treatment the author had. One item in particular sparked his curiosity: Joyce's reference in two separate 1928 letters to the injections of arsenic and phosphorous he was receiving.

"It wasn't too long before I found a medication that fit: galyl, a compound of arsenic and phosphorus that doctors injected multiple times. Galyl was only used to treat syphilis," said Birmingham.

The drug is obscure, and Birmingham believes Joyce opted for this treatment, rather than the more effective drug salvarsan, because one of salvarsan's side effects was that it could further damage his eyesight – and Joyce hated the idea of having to dictate his work. Today, syphilis is treated with a shot of penicillin.

"The more challenging part was making sure that galyl was the only injectable medication of arsenic and phosphorus. I had to prove a negative. Early 20th-century medicine isn't my area of expertise, so I contacted a couple of librarians at Harvard's Library of Medicine and the Centre of the History of Medicine, and they helped me search. I went through various pharmacopeias and national formularies (French, British and American) and couldn't find any other example of injectable medication of arsenic and phosphorus," said Birmingham.

Joyce's doctor, Louis Borsch, whom he had been seeing regularly for years, was treating him – ineffectively – for syphilis, according to the academic. Borsch "was reputable, and he knew what he was doing," said the scholar. So "the only way Joyce didn't have syphilis is if his examining doctor was somehow wrong. Syphilis is not difficult to diagnose, and you don't give someone three weeks of injections of an anti-syphilitic medication unless you're confident in your diagnosis.

"Add to Joyce's treatment (and his penchant for prostitutes) the fact that syphilis is virtually the only reasonable explanation for Joyce's decades of symptoms, and it seems rather difficult to refute."

The disease clearly preoccupied the author – in his story The Sisters, part of Dubliners, he writes of the death of a priest whose illness, which "affected his mind", is sometimes diagnosed as the final stages of syphilis. "Every night as I gazed up at the window I said softly to myself the word paralysis," says Joyce's boy narrator. "But now it sounded to me like the name of some maleficent and sinful being. It filled me with fear, and yet I longed to be nearer to it and to look upon its deadly work." In Ulysses, he writes: "Thrust syphilis down to hell and with him those other licensed spirits", and warns that Dublin's "nighttown" and its "women of ill fame" is "a regular deathtrap for young fellows".

Birmingham believes his diagnosis "gives us a very different vision" of the author. "Without the diagnosis, Joyce's letters make him seem as if he's a grousing hypochondriac or someone who just isn't particularly healthy. The truth is that he was in serious pain," said the academic. "He suffered deeply and privately, and the chasm between his private affliction and his public life helped to shape the way he wrote … How the news of a syphilitic Joyce changes the way we understand his life and his fiction is just beginning. This is what makes scholarship so exciting."

Mark Traynor, manager of the James Joyce Centre in Dublin, said that he had "heard mutterings" of the theory before, including in Ferris's work. "To be honest I've always categorised such theories as half-baked retrospective diagnosis. But in this case it does seem plausible," said Traynor. "My understanding is that pre-penicillin the disease was really prevalent but so taboo that no one talked about it. So it is certainly possible Joyce 'suffered in silence' … If this proves to be the case it certainly would add to our understanding of how deeply he suffered. Whether or not this is some new prism through which we read his work is doubtful, however."

Professor Derek Attridge at the University of York said that Deborah Hayden had also supported the idea that Joyce had syphilis in her recent book Pox. "The two well-known letters Birmingham refers to are about the treatment for Joyce's problems with his eyesight, and the way they are phrased don't sound like someone admitting he has syphilis, but the identification of arsenic and phosphorus with galyl is interesting, and as far as I know, new," said Attridge.