Differential diagnosis
Despite many distinguishing features, the clinical spectrums of following diseases may overlap with chancroid:
Primary syphilis
Genital herpesPractical clinical approach for this STI as Genital Ulcer Disease is to rule out top differential diagnosis of Syphilis and Herpes and consider empirical treatment for Chancroid as testing is not commonly done for the latter. Comparison with syphilis
There are many differences and similarities between the conditions syphilitic chancre and chancroid:
SimilaritiesBoth originate as pustules at the site of inoculation, and progress to ulcerated lesions
Both lesions are typically 1–2 cm in diameter
Both lesions are caused by sexually transmissible organisms
Both lesions typically appear on the genitals of infected individuals
Both lesions can be present at multiple sites and with multiple lesionsDifferencesChancre is a lesion typical of infection with the bacterium that causes syphilis, Treponema pallidum
Chancroid is a lesion typical of infection with the bacterium Haemophilus ducreyi
Chancres are typically painless, whereas chancroid are typically painful
Chancres are typically non-exudative, whereas chancroid typically have a grey or yellow purulent exudate
Chancres have a hard (indurated) edge, whereas chancroid have a soft edge
Chancres heal spontaneously within three to six weeks, even in the absence of treatment
Chancres can occur in the pharynx as well as on the genitals

Prevention
Chancroid spreads in populations with high sexual activity, such as prostitutes. Use of condom, prophylaxis by azithromycin, syndromic management of genital ulcers, treating patients with reactive syphilis serology are some of the strategies successfully tried in Thailand.
Chancroid ( SHANG-kroyd) is a bacterial sexually transmitted infection characterized by painful sores on the genitalia. Chancroid is known to spread from one individual to another solely through sexual contact. However, there have been reports of accidental infection through another route which is by the hand. While uncommon in the western world, it is the most common cause of genital ulceration worldwide. Signs and symptoms
These are only local and no systemic manifestations are present. The ulcer characteristically:

Ranges in size dramatically from 3 to 50 mm (1/8 inch to 2 inches) across
Is painful
Has sharply defined, undermined borders
Has irregular or ragged borders, described as saucer-shaped. Has a base that is covered with a gray or yellowish-gray material
Has a base that bleeds easily if traumatized or scraped
Painful swollen lymph nodes occur in 30–60% of patients. Dysuria (pain with urination) and dyspareunia (pain with intercourse) in femalesAbout half of infected men have only a single ulcer. Women frequently have four or more ulcers, with fewer symptoms. The ulcers are typically confined to the genital region most of the time. The initial ulcer may be mistaken as a "hard" chancre, the typical sore of primary syphilis, as opposed to the "soft chancre" of chancroid.Approximately one-third of the infected individuals will develop enlargements of the inguinal lymph nodes, the nodes located in the fold between the leg and the lower abdomen.Half of those who develop swelling of the inguinal lymph nodes will progress to a point where the nodes rupture through the skin, producing draining abscesses.