Reactive arthritis

Reactive arthritis can cause inflammation of the tendons around the joints, such as the Achilles tendon at the back of the ankle. If both the tendons and joints of the fingers or toes are affected at the same time it can cause a sausage-like swelling of the fingers or toes (dactylitis).

Often joint pain and swelling are the only symptoms of reactive arthritis. However other possible symptoms include:

• inflamed, red eyes (conjunctivitis)
• scaly skin rashes over the hands or feet (known as keratoderma blenorrhagica)
• diarrhoea, which may start some time before the arthritis
• mouth ulcers
• inflammation of the genital tract producing a discharge from the vagina or penis
• a sore rash over the end of the penis.

For the majority of people, reactive arthritis disappears completely within six months. During this time, it often runs a fluctuating course, with better and worse days. Only a small number of people go on to develop a persistent arthritis that requires long-term treatment.

It isn't known exactly why this happens. One theory is that once the immune system has dealt with the original infection, debris (such as dead bacteria) may be carried through the bloodstream and deposited in the lining of the joints, where it triggers an inflammatory reaction. The original infection may be food poisoning, usually involving diarrhoea or an infection of the genital tract, such as chlamydia or non-specific urethritis (NSU).

Although there's no particular family tendency to develop reactive arthritis, if you have a particular gene, HLA B27, then you may have a greater chance of developing reactive arthritis. About 1 person in every 14 has this gene. Having the HLA B27 gene may also increase the likelihood of a person having recurring spells of reactive arthritis in response to further triggering infections.

It's also quite common to develop joint pains linked to a viral infection, such as parvovirus or hepatitis, or following vaccination against a virus – but this is usually referred to as viral-associated or post-viral arthritis, and usually clears up within a few weeks.

There is no specific test for reactive arthritis, and it isn't always possible to establish a link with a previous infection. The particular combination of symptoms can itself help with diagnosis, and tests can either support a diagnosis of reactive arthritis or exclude other possible causes – for example:

• A stool sample or swabs taken from the penis or vagina can be tested for signs of inflammation or infection
• Blood tests can be used to measure the level of inflammation. Blood tests can also be used for genetic analysis (tests for the HLA B27 gene) or to identify antibodies associated with other forms of arthritis.

If your eyes are sore and red you may be examined by an eye specialist in order to check for serious inflammation of the eye, known as iritis.

Treating the infection

If you are found to have a bowel infection or a genital tract infection you will probably be given antibiotics. These will help to eliminate the organism that is causing the infection, but are unlikely to help with the joint inflammation.

Conjunctivitis is often treated with eye drops or ointment. More severe eye inflammation, such as iritis, may need steroid eye drops.

Treating the joint pain and swelling

Joint inflammation is treated according to severity. Mild to moderate arthritis may be relieved with non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, indometacin or diclofenac.

In addition to drug treatments, resting wrist splints, heel and shoe pads, and sometimes bed rest may be helpful in the short term. Ice packs and heat pads can also help to relieve joint pain and swelling.

Treating severe or persistent arthritis

More severe symptoms may need a steroid injection into the inflamed joint (intra-articular injection). Removal of fluid (aspiration) is often used to relieve knee pain. Occasionally, severe arthritis may need steroid injections into a muscle (intramuscular injection) or vein (intravenous injection), or alternatively short courses of low-dose steroid tablets.

If steroid treatments don't quickly bring the disease under control, disease-modifying drugs – such as sulfasalazine and, occasionally, methotrexate or azathioprine – may be used.

Exercise

When the joint inflammation is active, it may make you feel tired and generally unwell. Rest can play an important role in recovery during the early stages of reactive arthritis.

However, it's also important to keep your joints moving and try to maintain muscle strength. A physiotherapist can advise on exercises that will help mobility while at the same time avoiding too much strain on inflamed joints.