Actress and singer Selena Gomez told fans she had been battling with the autoimmune disease lupus in 2015. tinseltown/Shutterstock

Cases of autoimmune disease have risen in recent years but because it is frequently invisible and only fairly recently has there been a big effort to increase awareness of the condition (or, rather, multiple conditions), many sufferers have spent years of doctors’ trips and hospital visits before receiving a diagnosis. As one patient describes it in The New Yorker, "I got sick the way Hemingway says you go broke: 'gradually and then suddenly.'"

There is, however, good reason to remain optimistic. A team of researchers from Yale University may have found the underlying cause as well as promising methods of treating the illness.

The paper, published in the journal Science, has linked autoimmune reactions to a bacteria in the gut called Enterococcus gallinarum. An autoimmune response, they say, can be triggered when the bacterium spontaneously migrates from the gut to other organs in the body, such as the spleen, liver, and lymph nodes.

An autoimmune disease is a chronic inflammatory condition caused by a person’s own immune cells, which mistakenly believes the body is under threat and so responds by attacking healthy tissues. Lupus, rheumatoid arthritis, and Hashimoto’s thyroiditis are just three of over a hundred conditions that fit into this category. Now, they can be added to the long list of illnesses linked to the health of gut bacteria.

During the study, the researchers genetically engineered mice to be susceptible to autoimmune diseases. They then analyzed the gut bacteria to identify those that caused inflammation or were involved in the production of antibodies known to promote autoimmune responses. The culprit was Enterococcus gallinarum.

The results were confirmed when they compared cultured liver cells of healthy people versus those of people with an autoimmune disease and found traces of Enterococcus gallinarum in the latter group.

Excitingly, they weren’t just able to identify the source, they developed effective ways to reduce autoimmune symptoms. By using antibiotics or a vaccine, the researchers dulled symptoms by suppressing the growth of Enterococcus gallinarum. It is hoped that this research can be developed into successful treatment options for certain autoimmune diseases, including autoimmune liver disease and systemic lupus.

"The vaccine against E. gallinarum was a specific approach, as vaccinations against other bacteria we investigated did not prevent mortality and autoimmunity," Martin Kriegel, senior author, explained in a statement. “The vaccine was delivered through injection in muscle to avoid targeting other bacteria that reside in the gut.

"Treatment with an antibiotic and other approaches such as vaccination are promising ways to improve the lives of patients with autoimmune disease.”