Syphilis is an important sexually transmitted infection. There has been an epidemic of syphilis amongst men who have sex with men in the United Kingdom in the last decade. Early infection with syphilis causes a genital ulcer followed, in the absence of treatment, by a generalised illness often accompanied by rash. Studies on the pathogenesis of syphilis have been limited because it is not possible to grow syphilis outside of the body. New approaches using molecular tests allow the immune response of the patient to infection to be measured directly from a swab of a genital ulcer or rash and/or a blood sample and also allow the whole genetic sequence of the bacteria to be obtained from a swab.

In this study the investigators will collect swabs from ulcers or rashes and a blood sample from patients with syphilis and measure both the response of the patient immune system and the genetic sequence of the bacteria. Patients will be enrolled at sexual health clinics in the United Kingdom. Patients will receive standard medical care including standard treatment for syphilis in line with national guidelines. Standard management already includes collection of a swab and a blood sample. For this study an additional swab sample and an additional 5ml of blood will be collected for use in this research project. By better understanding host immune system responds to infection with syphilis the studies aims to gain better insights in to the pathogenesis of this important sexually transmitted disease.

Inclusion Criteria:

• Early infectious syphilis with exudative skin/genital lesions from which a lesion swab can be obtained

Exclusion Criteria:

• Age <18 years
• Unable to provide consent
• Patients with other stages of syphilis apart from Primary or Secondary OR patients without a lesion from which swabs can be obtained

Early infectious syphilis with exudative skin/genital lesions from which a lesion swab can be obtained