Chancroid is a sexually transmitted infection (STI) caused by Haemophilus ducreyi, a gram-negative facultative anaerobe.

Chancroid is rare in the United States, and prevalence has been decreasing worldwide. Infection, usually associated with sporadic outbreaks, may still be a cause of genital ulcer in certain regions in Africa and the Caribbean. Cases may be underestimated due to the difficulty in isolating the organism and subsequent underreporting.

Individuals in communities with high rates of commercial sex (sex workers, clients, and their partners) are at higher risk for chancroid. In addition, chancroid increases the risk for transmission of HIV. Similarly, HIV infection increases the risk of chancroid and leads to atypical presentations such as a longer incubation period, multiple ulcers, and extended healing times. Extragenital chancroid is also more common in HIV coinfection.

The period of incubation is 3-7 days. Patients rarely present with prodromal symptoms. The earliest form of presentation is a painful genital papule that becomes an ulcer with a shaggy (ragged) border within a few days. If the lesion is neglected and untreated, it can cause significant tissue destruction.