• A sexually transmitted infection characterized by painful genital ulcerations and inguinal adenopathy
  • Uncommon in the United States, present worldwide
  • Chancroid is endemic in developing countries, especially sub-Saharan Africa and North India, and is a cofactor for HIV transmission.
  • Synonyms: soft chancre; ulcus molle



  • <50 cases reported to CDC from 2012 to 2016 (1)
  • Actual numbers are likely higher due to lack of testing and underreporting.

Endemic in developing countries; annual estimated global prevalence of 4 to 6 million; actual prevalence is unknown (2).

  • More common in
    • Sub-Saharan Africa
    • Southeast Asia
    • Latin America

Etiology and Pathophysiology

  • Haemophilus ducreyi enters through abraded skin during sexual activity, attaching to susceptible cells.
  • Cytolethal distending toxin facilitates epithelial injury and ulcer formation (3).
  • The bacterium contains a fimbria-like protein (flp) operon encoding proteins to promote adherence and pathogenesis.
  • Dendritic cells and natural killer cells respond to H. ducreyi. This innate host response determines bacterial clearance versus disease progression.
  • H. ducreyi (gram-negative rod) is a uniquely human pathogen.
  • One colony-forming unit (cfu) of H. ducreyi results in papule formation in 50% of individuals. 90% develop papule with 100 cfu (3).
  • Following exposure, a local tissue reaction generates an erythematous papule that progresses to a pustule in 4 to 7 days. Central ulceration and necrosis follow, leading to the characteristic chancre.
  • In addition to genital ulcers, H. ducreyi causes chronic skin ulcerations, particularly in children from developing countries.

Risk Factors

  • Multiple sexual partners
  • Uncircumcised men
  • Other genital ulcerative diseases (syphilis, herpes simplex)
  • HIV

General Prevention

Proper condom use and safe sexual behavior

Commonly Associated Conditions

  • Syphilis: concurrent in 10% of patients
  • Herpes simplex virus (HSV) or HIV infection

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