Syphilis is an infectious disease, transmitted sexually, caused by Spirochaeta, Treponema pallidum, capable of involving every structure of the body. (a) Incubation period: 9 to 90 days. (b) T. Pallidum—is a closed coiled organism’s length 6 to 15 μm and consisting of 8 to 24 coils and its width is seldom more than 25 μm. It multiplies by transverse fission. Pathology: In case of acquired syphilis, T. pallidum gets into the body tissue, possible through a small abrasion, usually as a result of sexual contact. Acquired syphilis: Classification: Early syphilis: Early syphilis is diagnosed in first two years of infection. It consists or primary stage, secondary stage, recurrent stage (sometimes of primary but usually secondary type) and early latent stage, it is infectious phase of syphilis. Late syphilis: Late syphilis is diagnosed after two years of infection. It consists of late latent stage, and tertiary state. Syphilis early primary: After the incubation period of 9 to 90 days usual time being. It is usually single but occasionally multiple ulcers appearing usually on external genitalia. There is associated inguinal lymphadenopathy which is usually bilateral, painless non-tender, discrete, freely mobile and rubbery in consistency. If untreated it heals in three to ten weeks time leaving a thin scar. Diagnosis: 1. By clinical features + history of contact as described above. 2. By identifying Treponema pallidum kfkrom sore by dark ground examination. 3. Blood STS. Treatment: Injection benzathine penicillin 2.4 MU (1.2 MU in each buttock). Secondary syphilis: The interval between primary chancre and secondary syphilis is generally 6 to 8 weeks. Constitutional symptoms may precede or accompany. They are as follows. (a) Headache, malaise, weight loss, anorexia. (b) Low grade fever. (c) Hoarseness of voice. (d) Aching pains in long bones, muscles, joints. Sings: (i) Seventy five percent secondary syphilis (SS) patients have skin involvement. (ii) Fifty percent of SS patients have gen-lymphadenopathy. (iii) Thirty percent have mucosal involvement. (iv) Ten percent have involvement of bone, CNS, eye, Viscera. Types of eruption: Macular, popular, papulosquamous, pustular. Treatment: (a) Penicillin is the drug of choice. (b) Benzathine penicillin—2.4 mega units (IM). (c) Procaine penicillin—6 lac units IM daily × 10 days (IM). (d) Cap tetracycline 500 mg × quid for 15 days. Syphilis early congenital: Mechanism of transmission: Infection is acquired during foetal life from infected mother specially if she is suffering from early syphilis. Divided into three types: (a) Early, (b) Late, and (c) Stigmata. Syphilis early congenital: The infection is acquired and manifested in the first two years of life. Skin lesion: Earliest type is bullous rash. Sometimes called syphilitic pemphigus which may or may not be present at birth. Lesions of mucous membrane Mucous patches are similar to those of secondary syphilis. Discharge known as syphilitic rhinitis. Diagnosis: 1. DGI from lesions specially moist lesions, 2. Special serological tests and routine STS. 3. By clinical features described above. Treatment: Prophylactically treat the mother. For symptomatic infants: Aqueous crystalline penicillin (G 5000) units/kg/IM/IV in 2 divided doses for a minimum period of 10 days. Jarisch herxheimer reaction: Jarisch Herxheimer reaction is focal and systemic reaction, following the first dose of potent syphilitic remedy. Syphilis latent: Syphilis early latent and 2. Syphilis late latent. Syphilis early latent: It is diagnosed within first two years of infection. Essential features: Absence of sign and symptoms of syphilis. (b) Positive blood STS. (c) Negative k test of CSF. Treatment: Same as in primary and secondary stage of early syphilis. Syphilis late latent: It is diagnosed after two years of infection. (i) Absence of sing and symptoms of syphilis. (ii) Positive blood STS. (iii) Test of CSF—may be positive. Other investigations: CSF examination to exclude, asymptomatic neurosyphilis. Treatment: Benzathine penicillin G: 2.4 MU weekly for three successive weeks (Total 7.2 MU). Neurosyphilis: Treponema pallidum invades the central nervous system during the early stage of syphilitic infection, which is indicated by changes in CSF in from 20 to 37 percent of cases. Classification of neurosyphilis: (i) Meningeal, cerebral, spinal. (ii) Vascular cerebraal spinal. (iii) Parenchymatous cerebral—15%. Meningeal involvement: Meningeal involvement can be seen in the secondary stage, at any time in the later stages. Symptoms and signs: Headache of weeks or even longer duration. Convulsions, aphasia and mental confusion. Monoplegia, hemiplegia, papilledema is common. Vascular involvement: Headache, giddiness or mental disturbances. When there is: (a) Middle cerebral thrombosis, there is contralateral hemiplegia and aphasia. (b) Anterior cerebral thrombosis, there may be mental deterioration. (c) Cerebellar artery thrombosis produces vertigo, vomiting. (d) Basilar artery thrombosis is rare, when involved, 3rd cranial nerve palsy. Parenchymatous involvement—general paralysis (GPI): The weight of the brain is diminished due to cortical atrophy. Do not usually appear before 10 years of infection. Patient becomes irritable, his/her memory begin to fail, she/he is unable to concentrate. His/her personality and behavior change gradually. Gumma: Gumma is now a very rare condition. It affects the meninges and the parenchyma of the brain in addition to that of skull (bone). Diagnosis of Late Syphilis: (a) History and clinical manifestations. (b) Positive blood STS. (c) Specific test viz. FTA-ABS test. (d) Biopsy and histopathological examination. Treatment: (a) Injection benzathine, penicillin 2.4 MU. (b) 1.2 MU in each buttock—after ST. (c) Total dose 2.4 MU biweekly for two weeks.