Pathogens are Haemophilus ducreyi, for gram-negative bacilli, was a short rod, both ends blunt round, about 1. 5 ~ 2um, W 0. 2um, was also known as chain of longitudinal rows, so bacteria can be parallel to arranged in several rows or showed a fish-shaped. Most exist in cells, a small number of cells was found in group-like arrangement. Of heat tolerance is poor, at 65 ℃ may soon die, but the cold strong, at low temperature can be long-term survival.
Incubation period is usually 2 to 3 days, the typical early chancre was a small inflammatory papules, rapidly become pustules formed after ulcerated round or oval shallow ulcers, nature soft, pain, obviously, is about a few millimeters in diameter ~ 2cm , edges irregular, showing Chuanzao nature, surrounded by Yan Xing Hongyun, ulcers at the bottom covered with moss and greyish yellow necrotic purulent discharge pus, easy bleeding. The number of the first 1 ~ 2 may be due to their own vaccination can occur around 2 to 5 clusters of satellite-like ulcers. Coronal male predilection in the penis, foreskin, glans, anal. Female predilection in the size of the labia, lace labia, the clitoris and the anus, may also occur in the cervix and the urethra.
According to a history of dirty sexual intercourse, outside of one or more painful genital ulcers, unilateral groin pain transverse Xuan, secretions from the ulcer or inguinal lymph node extract for Gram stain smears can detect Gram - negative short-rod-like chain of bacteria, Treponema pallidum and syphilis sero-negative examination can be made the diagnosis, if necessary, can be bacterial culture.
Sulfa drugs as the drug of choice can be served cotrimoxazole 2 times a day for each four, at least 7 days; or erythromycin 0. 5g 4 times a day, 7 days; can also serve tetracycline 0. 5g per day four times, a total of 10 ~ 20 days.