Description

• 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

Epidemiology

Incidence

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

Prevalence
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