Strictly speaking, a definitive diagnosis of chancroid should only be made where H. ducreyi is recovered from genital ulcers. The disease was prevalent in war-times. Recently, there have been outbreaks in the United States, Canada and some European countries. It is thought that prostitutes constitute an important reservoir of infection. The disease is also more common in the uncircumcised men, and in unhygienic and low socioeconomic conditions.
Asymptomatic carriers exist.
The apparent lower incidence in 1994 and 1995 could possibly be due to a preferred categorisation of cases into the genital ulcer group. The causative organism, Haemophilus ducreyi, was first described by Ducrey in 1889. It is a Gram negative coccoid-bacillary rod predominantly located in the extra cellular spaces. H. ducreyi is a fastidious organism, requiring stringent conditions for a successful growth in vitro. Chancroid is almost exclusively a sexually transmitted disease.