Tick-borne relapsing fever
Tick-borne relapsing fever is found primarily in Africa, Spain, Saudi Arabia, Asia, and certain areas of Canada and the western United States. Other relapsing infections are acquired from other Borrelia species, which can be spread from rodents, and serve as a reservoir for the infection, by a tick vector. Borrelia crocidurae – occurs in Egypt, Mali, Senegal, Tunisia; vectors – Carios erraticus, Ornithodoros sonrai; animal host – shrew (Crocidura stampflii)
Borrelia duttoni, transmitted by the soft-bodied African tick Ornithodoros moubata, is responsible for the relapsing fever found in central, eastern, and southern Africa. Borrelia hermsii
Borrelia hispanica
Borrelia miyamotoi
Borrelia parkeri
Borrelia turicatae
Borrelia persicaB. hermsii and B. recurrentis cause very similar diseases. However, one or two relapses are common with the disease associated with B. hermsii, which is also the most common cause of relapsing disease in the United States. (Three or four relapses are common with the disease caused by B. recurrentis, which has longer febrile and afebrile intervals and a longer incubation period than B. hermsii.) Diagnosis
The diagnosis of relapsing fever can be made on blood smear as evidenced by the presence of spirochetes. Other spirochete illnesses (Lyme disease, syphilis, leptospirosis) do not show spirochetes on blood smear. Although considered the gold standard,  this method lacks sensitivity and has been replaced by PCR in many settings. Treatment
Relapsing fever is easily treated with a one- to two-week-course of antibiotics, and most people improve within 24 hours. Complications and death due to relapsing fever are rare.Tetracycline-class antibiotics are most effective.
Synovial chondromatosis is a locally aggressive bone tumor of the cartilaginous type. It consists of several hyaline cartilaginous nodules and has the potential of becoming cancerous. Signs and symptoms
People usually complain of pain in one joint, which persists for months, or even years, does not ease with exercise, steroid injection or heat treatment, shows nothing on X-ray, but shows a definite restriction of movement. There are 3 defined stages to this disease:

early: no loose bodies but active synovial disease;
transitional: active synovial disease, and loose bodies;
late: loose bodies but no synovial disease;In the early stages of the disease it is often confused with tendinitis and/or arthritis. Once it reaches transitional the loose bodies become apparent with X-ray in greater than 70% of cases, with MRI often showing where xray fails. In experienced hands, ultrasound is also useful for the diagnosis.Rare and little known, with currently no known cure, the disease gradually forms blisters in the thin flexible membrane of the synovium, which calcify and enlarge. These nodules eventually break free and float around the joint space becoming larger – these add to the discomfort and stiffness of the joint. The affected tissue will show up as a semi-solid mass in an MRI scan, final diagnosis is usually confirmed by taking a biopsy. The disease generally affects only one of the larger weight bearing joints (hip, ankle, knee) – although the elbow, and wrist can also be affected.