Reactive Arthritis Statistics

Reactive arthritis is a condition that causes redness and swelling (inflammation) in various joints in the body, due to a gastrointestinal infection such as food poisoning or after a urinary infection. The disorder primarily affects the knees, feet, toes, hips, and ankles.

The difference between this and other forms of arthritis is that it occurs as a reaction to an inflammation in another part of the body, for example, the intestine, caused by viral food poisoning. If you or a loved one has suffered from reactive arthritis after food poisoning, speak to a reactive arthritis attorney about your options for financial compensation. 

Other Causes of Reactive Arthritis

Reactive arthritis is not a contagious condition but can be caused by some infections that are. A wide range of food poisoning bacteria, including salmonella, E. coli, yersinia, campylobacter, and shigella, can all cause reactive arthritis. Apart from food poisoning, reactive arthritis can result from viral infections such as a cold, a sexually transmitted infection (STI), such as chlamydia and HIV, or if you, or someone close to you, has recently had glandular fever or slapped cheek syndrome.

The body’s immune system overreacts to the infection and begins attacking healthy tissue, causing it to become inflamed. However, the exact reason why this occurs is unknown.

Another characteristic is people who have a gene called HLA-B27 are much more likely to develop reactive arthritis than those who don’t, but it is unclear why.

Risk Factors for Reactive Arthritis

The most significant risk factors for getting reactive arthritis are having an illness from contaminated food, an infection from sexual contact, or being male. Reactive arthritis is most prevalent among adults between the ages of 20 and 40. However, it has also been reported in children and the elderly. When children do present with reactive arthritis, they are typically over the age of nine, and it is predominantly a result of a foodborne illness. Women usually develop milder symptoms and may often go undiagnosed. 

Men and women develop reactive arthritis at almost the same rate after a food-related infection. However, a 2020 review discovered males are nine times more likely than females to suffer reactive arthritis from an STI. The risk of developing reactive arthritis is about 50 times greater in those people who are HLA-B27 positive. The true incidence of the condition, however, is most likely underestimated as milder forms of the condition go misdiagnosed or undiagnosed. 

Complications of Reactive Arthritis

Reactive arthritis may cause arthritis symptoms, such as joint pain and inflammation but can also cause urinary tract symptoms and eye infection (conjunctivitis). Symptoms can last from three to 12 months, and treatment will depend on the patient’s age, general health, and ailments. In a small number of people, the symptoms may turn into chronic disease and may also suffer further complications, including: 

• Recurrent arthritis (15-50%)
• Chronic arthritis or sacroiliitis (15-30%): Sacroiliitis is the inflammation of one or both of the sacroiliac joints, which are situated where the lower spine and pelvis connect. As a result, the patient can experience pain in the buttocks and lower back, possibly extending down one or both legs.
• Ankylosing spondylitis (30-50% of HLA-B27–positive patients): an inflammatory disease that can cause some of the small bones in the spine to fuse over time.
• Urethral stricture: Scarring in the urethra, restricting the flow of urine from the bladder, which can lead to inflammation and infections in the urinary tract.
• Secondary glaucoma: Any form of glaucoma resulting from an acquired condition (e.g., reactive arthritis), which causes optic nerve damage and vision loss.
• Cataracts: The clouding of the lens of the eye, leading to blurry vision.
• Cystoid macular edema: Multiple cyst-like (cystoid) areas of fluid appear in the macula and cause retinal swelling or edema. It is painless but can cause blurred or decreased central vision.
• Posterior and anterior synechiae: Synechiae are adhesions of the iris to ocular structures, which can cause issues of aqueous blockage, pupil dilation, and more.
• Cyclitic membrane: A membrane that develops across the back of the lens of the eye as a result of inflammation.
• Vitreous opacification: Process by which the vitreous body of the eye goes from clear to cloudy, which can result in mild to severe vision loss.
• Psoriatic arthritis:  A form of arthritis that affects some people who have psoriasis—a disease that causes red patches of skin topped with silvery scales.
• Erythroderma (rare): A severe and potentially life-threatening inflammation of most of the body’s skin surface.

Global Prevalence

Reactive arthritis is relatively rare, and in population-based studies, the incidence rate is reported to be 0.6 to 27 per 100,000. Around one percent of patients with non‐gonococcal urethritis and up to three percent of patients with bacterial foodborne infection subsequently develop reactive arthritis. Remarkably, the incidence of reactive arthritis in foodborne illness outbreaks varies from zero percent to three or four percent, even when the infecting strains are similar but not exactly the same. 

The incidence in Europe is estimated at 30 per 100 000. In Norway, there is an annual incidence rate of 4.6 per 100,000 for chlamydia-induced reactive arthritis and five per 100,000 for reactive arthritis due to foodborne bacteria. The incident rate of reactive arthritis appears to be related to the prevalence of HLA-B27 in a population and to the rate of urethritis, which is inflammation of the urethra or cervicitis, which is an irritation or infection of the cervix, and gastrointestinal diseases. There are more than 40 subtypes of HLA-B27, which can be somewhat segregated geographically. For example, the subtype B2705 is predominantly found in Latin America, Brazil, Taiwan, and parts of India. In Finland, where the population with HLA-B27 is higher, nearly two percent of males were found to have developed reactive arthritis after suffering from nongonococcal urethritis. Whereas, in the United Kingdom, reactive arthritis was only discovered in 0.8% of males after urethritis. 

In the United States, only two population-based studies have been conducted on reactive arthritis following foodborne illness outbreaks. However, the studies were primarily focused on “Reiter’s syndrome” following Shigella and Salmonella infections rather than reactive arthritis. Additional epidemiologic studies are needed to determine the burden of reactive arthritis following a foodborne illness.