Sexually Transmitted Infections: Chancroid

Introduction

• Description: Infection by Haemophilus ducreyi results in chancroid, a group of infrequently encountered sexually transmitted infections (STIs). Chancroid is more common than syphilis in some areas of Africa and Southeast Asia, but it is uncommon in the United States.

• Prevalence: In the United States, 10–15 cases per year are reported (8 cases in 2019), generally in small, sporadic outbreaks (underreporting and lack of testing may underestimate the actual incidence).

• Predominant Age: Younger reproductive age.

• Genetics: No genetic pattern.

Etiology and Pathogenesis

• Causes: H. ducreyi is not capable of infecting intact skin; thus, the lesions of chancroid tend to be found in areas traumatized by sexual activity. Material from the vulvar ulcers is virulent and can infect other body sites.

• Risk Factors: Sexual trauma and exposure to the infective agent, prostitution, and human immunodeficiency virus (HIV) infection.

Signs and Symptoms

• One to three painful “soft chancres” 3–10 days after exposure (these break down over approximately 2 weeks to form shallow, progressive ulcers with red, ragged, undermined edges, with little surrounding inflammation; autoinoculation is common, resulting in lesions at various stages of evolution).

• Unilateral adenopathy progressing to massive enlargement and inflammation (“buboes,” 50%)

• The combination of a painful ulcer and tender inguinal adenopathy symptoms occurs in one-third of patients and suggests chancroid. When accompanied by suppurative inguinal adenopathy, they are almost pathognomonic. A definitive diagnosis of chancroid requires the identification of H. ducreyi on special culture media that are not widely available from commercial sources; even when using these media, sensitivity is ≤80%.

Diagnostic Approach