What Is Lyme Arthritis?
Lyme arthritis is one of the diseases caused by the bacterium Borrelia burgdorferi (Lyme borreliosis), which is transmitted through the bite of hard body ticks, including Ixodes ricinus.
Although the skin, central nervous system, heart, eye, and other organs may be affected by Borrelia burgdorferi infection, the joints are the exclusive target in most cases of Lyme arthritis. However, there may be a history of skin involvement in the form of migratory erythema, a red rash that is expanding at the site of the tick bite. In very rare occasions, cases of Lyme arthritis that are not treated can progress to central nervous system involvement.
Fortunately, only a minority of children with arthritis have Lyme arthritis. However, Lyme arthritis is probably the most common arthritis that occurs after a bacterial infection in children and adolescents in Europe. It rarely occurs before 4 years of age, so it is mainly a disease of school-age children.
It occurs in all areas of Europe but is prevalent in Central Europe and southern Scandinavia, around the Baltic Sea. Although transmission depends on the bite of infected ticks, which are active from April to October (depending on humidity and environmental temperature), Lyme arthritis can be started at any time of the year due to the long and variable time between the bite infectious of the tick and the onset of joint inflammation.
The cause of the disease is the Borrelia burgdorferi bacterium, which transmits through the bite of the Ixodes ricinus tick. The most ticks are not infected, so most stings from hard body ticks do not result in infection; also, most infections, if they are treated in the migratory erythema phase, do not progress to more advanced stages of the disease, including Lyme arthritis.
This is especially the case if the first stages, including migratory erythema, have been treated with antibiotics. So, although the Lyme borreliosis, in the form of migratory erythema, may occur in 1 out of every 1,000 children a year, the onset of Lyme arthritis, late manifestation of the disease, is a rare event.
The main symptoms of Lyme arthritis are inflammation joint with effusion and limited movement in the affected joints. The enormous inflammation is usually accompanied by little or no pain. The most affected joint is the knee, although it can affect other large and little joints. It is rare that the knee is not affected since 67% of cases present monoarthritis (swelling and/or joint limitation due to the pain of a single joint) in that area. More than 95 % of cases follow an oligo articular evolution (up to 4 joints), usually with a knee joint like the only that remains inflamed after some time. Arthritis Lyme occurs as recurrent arthritis in 67% of cases (it means that arthritis goes away on its own after several days or a few weeks and, after an interval without symptoms, arthritis reappears in the same joints).
The frequency and duration of episodes of joint inflammation usually decrease with time, but in some cases, inflammation can increase since arthritis can become chronic.
There are also rare cases with long-term arthritis from the start (duration of arthritis of at least 3 months).
The disease is similar in adults and children. However, children may have a higher frequency of arthritis than adults. On the other hand, the younger the child, the faster the evolution and greater is the possibility of a successful treatment with antibiotics.
After treatment with antibiotics, in most cases, the disease will disappear without any consequences. There are individual cases in which definitive joint damage has occurred, including limitation of range of motion and premature osteoarthritis.
Since Lyme arthritis is an infectious bacterial disease, treatment is carried out by administering antibiotics. More than 80% of patients with Lyme arthritis are cured after one or two cycles of antibiotic treatment. In the remaining 10 or 20% of cases, the antibiotics usually do not cure the disease and anti-rheumatic treatment is necessary.