Venereal disease caused by the chlamydia organism, which probably penetrates the skin or mucous membrane during sexual contact. The disease is most common in the tropics, but is not unknown in Europe. In women there are often no symptoms; in men there is a fever ten days after infection, pain in the joints, and a pustule at the point at which the virus penetrated. The pustule usually disappears spontaneously, but after 1 to 3 weeks pus forms in the lymph nodes of the groin, causing an abscess. Diagnosis is by several blood tests and examination of samples of skin and lymph node tissue. If the disease is untreated tumours can appear around the anus, and in women on the labia and clitoris. Treatment is usually with antibiotics.