Illness

Throughout the entire novel, the health of Jane Fairfax is continually being worried about. Her aunts are concerned, even Mr. Knightley is concerned. It appears they all think she has something gravely wrong with her, even though all she complains about is fatigue and the odd cold. However, when Frank Churchill's aunt gets sick, people don't seem nearly as concerned with her well-being. Frank is just sent for from Highbury because his aunt can't be without him in her last moments. There may have been something to Jane's ill health after all though. During the time Austen wrote the novel, one disease people commonly believed in was consumption. Jane had all of the physical characteristics people most prone to this disease had. She is "the right age and also of the physical type who was thought likely to become consumptive." She is tall, slender, and uses her voice more than the average person. She also has a family history with consumption as her mother died from it. All of these factors make the worrying of her friends and family beneficial.
(To see more on this topic : http://austenonly.com/2009/11/03/were-they-right-to-worry-about-jane-fairfaxs-health/ )