The preferred antibiotic for most cases is benzathine benzylpenicillin injected into a muscle. In those who have a severe penicillin allergy, doxycycline or tetracycline may be used. In those with neurosyphilis, intravenous benzylpenicillin or ceftriaxone is recommended. During treatment people may develop fever, headache, and muscle pains, a reaction known as Jarisch–Herxheimer.In 2015, about 45.4 million people had syphilis infections, of which six million were new cases. During 2015, it caused about 107,000 deaths, down from 202,000 in 1990. After decreasing dramatically with the availability of penicillin in the 1940s, rates of infection have increased since the turn of the millennium in many countries, often in combination with human immunodeficiency virus (HIV). This is believed to be partly due to increased promiscuity, prostitution, decreasing use of condoms and unsafe sexual practices among men who have sex with men. Signs and symptoms
Syphilis can present in one of four different stages: primary, secondary, latent, and tertiary, and may also occur congenitally. It was referred to as "the great imitator" by Sir William Osler due to its varied presentations. Primary
Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person. Approximately 2–6 weeks after contact (with a range of 10–90 days) a skin lesion, called a chancre, appears at the site and this contains infectious spirochetes. This is classically (40% of the time) a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders approximately 0.3–3.0 cm in size. The lesion may take on almost any form.
Oslers nodes are painful, red, raised lesions found on the hands and feet. They are associated with a number of conditions, including infective endocarditis, and are caused by immune complex deposition. Their presence is one definition of Oslers sign. Causes
Oslers nodes result from the deposition of immune complexes. The resulting inflammatory response leads to swelling, redness, and pain that characterize these lesions. The nodes are commonly indicative of subacute bacterial endocarditis. 10–25% of endocarditis patients will have Oslers nodes. Other signs of endocarditis include Roths spots and Janeway lesions. The latter, which also occur on the palms and soles, can be differentiated from Oslers nodes because they are non-tender.Oslers nodes can also be seen in

Systemic lupus erythematosus
Marantic endocarditis
Disseminated gonococcal infection
Distal to infected arterial catheter

Etymology
Oslers nodes are named after Sir William Osler who described them in the early twentieth century. He described them as "ephemeral spots of a painful nodular erythema, chiefly in the skin of the hands and feet." == References ==