People who have recently had gut or urinary tract infections may be less likely to develop rheumatoid arthritis (RA), according to new research.
A study published in the Annals of the Rheumatic Diseases says that certain infections may curb the risk of developing the painful joint condition, perhaps because of the way in which these infections alter the types of bacteria resident in the gut.
Researchers from the Karolinska Institute in Stockholm, Sweden, looked at the impact of different types of infection on the risk of developing rheumatoid arthritis in almost 6,500 people living in south and central Sweden. Some 2,831 of the participants had been diagnosed with rheumatoid arthritis between 1996 and 2009, and the remaining 3,570 were healthy, but matched for age, sex and area of residence with the patients.
As part of the study, all participants were asked whether they had had gastroenteritis or any urinary tract or genital infections in the preceding two years. They were also asked if they had had prostatitis (inflamed prostate), or antibiotic treatment for sinusitis, tonsillitis/other throat infection or pneumonia during this time.
The analysis of the results showed that gut, urinary tract and genital infections within the previous two years were each associated with a significantly lowered risk of developing rheumatoid arthritis: by 29%, 22% and 20%, respectively. And the researchers noted that people who had all three types of infection in the preceding two years were 50% less likely to develop rheumatoid arthritis.
No such associations were found for sinusitis, tonsillitis or pneumonia.
The researchers said that their findings are “particularly interesting” in light of other studies suggesting that digestive system bacteria may play a role in the development of rheumatoid arthritis.
This might be because the linings of the gut are exposed to a high load of bacterial antigens, which may either initiate or modify inflammation, and so could possibly influence the risk of developing the disease.
The researchers also pointed out that infection sites identified in their study are primarily infected with gram negative bacteria, and antibiotics used to treat these bacteria have proved effective for treating rheumatoid arthritis, the British Medical Journal reported.