Adeline Virginia Woolf (; nee Stephen; 25 January 1882 - 28 March 1941) was an English writer who is considered one of the most important modernist twentieth century authors and a pioneer in the use of stream of consciousness as a narrative device. Virginia Stephen was born into an affluent household in South Kensington, London. She was the seventh child in a blended family of eight. Her mother, Julia Stephen, celebrated as a Pre-Raphaelite artist's model, had three children from her first marriage, her father Leslie Stephen, a notable man of letters, had one previous daughter, and four children were born in her parents' second marriage, of whom the most well known was the modernist painter, Vanessa Stephen (later Vanessa Bell).

Julia Stephen fell ill with influenza in February 1895, and never properly recovered, dying on 5 May, when Virginia was only 13. This was a pivotal moment in her life and the beginning of her struggles with mental illness. Essentially, her life had fallen apart. The Duckworths were travelling abroad at the time of their mother's death, and Stella returned immediately to take charge and assume her role. That summer, rather than return to the memories of St Ives, the Stephens went to Freshwater, Isle of Wight, where a number of their mother's family lived. It was there that Virginia had the first of her many nervous breakdowns, and Vanessa was forced to assume some of her mother's role in caring for Virginia's mental state. Stella became engaged to Jack Hills the following year and they were married on 10 April 1897, making Virginia even more dependent on her older sister.  George Duckworth also assumed some of their mother's role, taking upon himself the task of bringing them out into society. First Vanessa, then Virginia, in both cases an equal disaster, for it was not a rite of passage which resonated with either girl and attracted a scathing critique by Virgina regarding the conventional expectations of young upper class women "Society in those days was a perfectly competent, perfectly complacent, ruthless machine. A girl had no chance against its fangs. No other desires - say to paint, or to write - could be taken seriously". Rather her priorities were to escape from the Victorian conventionality of the downstairs drawing room to a "room of one's own" to pursue her writing aspirations. She would revisit this criticism in her depiction of Mrs Ramsay stating the duties of a Victorian mother in To the Lighthouse "an unmarried woman has missed the best of life".  The death of Stella Duckworth, her pregnant surrogate mother, on 19 July 1897, after a long illness, was a further blow to Virginia's sense of self, and the family dynamics. Woolf described the period following the death of both her mother and Stella as "1897-1904 -- the seven unhappy years", referring to "the lash of a random unheeding flail that pointlessly and brutally killed the two people who should, normally and naturally, have made those years, not perhaps happy but normal and natural". In April 1902 their father became ill, and although he underwent surgery later that year he never fully recovered, dying on 22 February 1904. Virginia's father's death precipitated a further breakdown. Later, Virginia would describe this time as one in which she was dealt successive blows as a "broken chrysalis" with wings still creased. Chrysalis occurs many times in Woolf's writing but the "broken chrysalis" was an image that became a metaphor for those exploring the relationship between Woolf and grief. At his death, Leslie Stephen's net worth was PS15,715 6s. 6d. (probate 23 March 1904)

Using a quote from the above article, answer the following question: how did stella die?
The death of Stella Duckworth, her pregnant surrogate mother, on 19 July 1897, after a long illness,