Relapsing fever is a vector-borne disease caused by infection with certain bacteria in the genus Borrelia, which is transmitted through the bites of lice or soft-bodied ticks (genus Ornithodoros). Signs and symptoms
Most people who are infected develop sickness between 5 and 15 days after they are bitten. The symptoms may include a sudden fever, chills, headaches, muscle or joint aches, and nausea. A rash may also occur. These symptoms usually continue for 2 to 9 days, then disappear. This cycle may continue for several weeks if the person is not treated. Causes
Louse-borne relapsing fever
Along with Rickettsia prowazekii and Bartonella quintana, Borrelia recurrentis is one of three pathogens of which the body louse (Pediculus humanus humanus) is a vector. Louse-borne relapsing fever is more severe than the tick-borne variety.Louse-borne relapsing fever occurs in epidemics amid poor living conditions, famine and war in the developing world. It is currently prevalent in Ethiopia and Sudan.Mortality rate is 1% with treatment and 30–70% without treatment. Poor prognostic signs include severe jaundice, severe change in mental status, severe bleeding and a prolonged QT interval on ECG.Lice that feed on infected humans acquire the Borrelia organisms that then multiply in the gut of the louse. When an infected louse feeds on an uninfected human, the organism gains access when the victim crushes the louse or scratches the area where the louse is feeding. B. recurrentis infects the person via mucous membranes and then invades the bloodstream. No non-human, animal reservoir exists.
Progressive pseudorheumatoid disyplasia (PPD or PPAC) is a disorder of bone and cartilage that affects many joints. The disorder leads to stiff joints, short stature and widening of the ends of the finger and toe bones as well as other tubular bones. Cause
PPD is due to a mutation in the Wnt1-inducible signalling protein 3 (WISP3) gene, which encodes a signalling factor involved in cartilage homeostasis. Symptoms
Symptoms are present typically between ages three and six years. Abnormal walking pattern
Weakness/fatigue
Stiffness in the joints of the fingers and knees

Diagnosis
Treatment
Prognosis
PPD has no severe effect on life span. Epidemiology
PPD is an extremely rare disease. In the United States the disease is estimated to affect less than 5,000 people and approximately 1 per million people in the United Kingdom however it is believed to be more common in Turkey and the Middle East. == References ==