In a 2019 Yahoo.com interview whilst celebrating 25 years of the film, screenwriter Eric Roth spoke about how he ended up writing the film. According to the interview Producer, Wendy Finerman is the one who suggested that Roth should adopt novelist Winston Groom’s 1986 novel of the same title. In the novel Jenny’s character suffers the same fate, however, unlike in the film, the illness from which she dies from is written to be Hepatitis C. According to the Centre for Disease Control Hepatitis C, a liver infection caused by the Hepatitis C virus can be spread through contact with blood from an infected person. Hence sharing needles used to inject and prepare drugs would be a cause of infection. Jenny’s arc in the book and the film has her struggle with substance abuse and thus it is plausible to conclude that Jenny’s death could have been caused by the disease in the film as well. 

However, the film’s failure to explicitly mention the cause of death has also led others to speculate other diseases as a result of Jenny’s arc in the film. At some points in the film, Jenny is seen to embrace the hippie-party girl lifestyle which largely contributed to the drug use. The sexual-carefree nature of this lifestyle has also led many to conclude that Jenny could have died from HIV/AIDS and or complications resulting from the virus. In the same Yahoo.com interview screenwriter Eric Roth whilst addressing the modern-day criticism of Jenny’s character which he deemed, “Unfair,” pointed out that Jenny could have gotten HIV from the sexual-carefree lifestyle coupled with the drug use. Jenny is shown to be part of Movements such as The Free love movement in the film. The movement despite having brought along with it social change notably carried on by Feminists and Gay liberation movements was unfortunately also characterized by care-free sexual behavior and drug use. In the film, Jenny is still actively living this lifestyle right up to 1976 which is when she goes back to Greenbow, Alabama to visit Forrest. According to the Centre for Disease Control on the History of HIV/AIDS, the disease has existed in the United States since the mid to late 1970s.

In the Yahoo.com interview, Mr. Roth also spoke about a sequel for the film that was supposed to air but didn’t after 9/11. In the interview, the screenwriter talks about the details of the sequel which was supposed to open with the news of Forrest Gump Jr having late-stage HIV as a result of having contracted the disease from his mother. According to the interview the screenwriter also pointed out that the arc would involve Forest helping his son deal with facing the stigma of living with the disease. This reveals that the writer had concluded that Jenny had indeed contracted and died from the virus. 

Drug use and care-free sexual behavior can, of course, lead to many other diseases. However, with the above-mentioned points, it’s highly unlikely that Jenny could have died from any other virus apart from HIV in the film. The novel explicitly mentions that the cause of death was Hepatitis C. The film’s decision to not mention the disease could have been for many reasons. For one Forrest Gump’s genre according to IMDB is drama and romance. Yet one of the things that the film is known for is its unconventional approach to storytelling with the writer infusing real-life historical events into the narrative like the Vietnamese war. The execution of these historical parts added a comedic tone that runs out throughout the film. This unconventional approach together with the on-and-off engagement between reality and fiction means that the writer had the freedom to decide what parts of reality he wanted to include and which he did not. 

Finally, throughout the film, Forrest is presented with many goals like setting up the shrimp Company which he promised his friend Bubba. Only many have presented Jenny as the main goal of Forrest’s entire arc. Hence the decision to not focus on the cause of death which would add tragedy to the already tragic end of the story isn’t one that many fans would take issue with, after all, who wishes for more tragedy.