Patients suffer from pain and deformities mostly in the hands and feet. It can occur at any age but the most common onset is between 40 and 60 years old and is three times more prevalent in women. The study showed a link between rheumatoid arthritis and Mycobacterium avium subspecies paratuberculosis, known as MAP. Humans can contract the bacteria through the consumption of infected milk, beef and produce fertilised by cow manure. “We don’t know the cause of rheumatoid arthritis, so we’re excited that we have found this association,” said one of the researchers Shazia Beg from the University of Central Florida (UCF) in the US.