Excerpt from Chancroid

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Background

Chancroid is a sexually transmitted genital ulcer disease (GUD) caused by the gram-negative bacillus Haemophilus ducreyi. It is characterized by the presence of painful ulcers and inflammatory inguinal adenopathy. Chancroid is often referred to as a soft chancre because the lesions are usually not indurated. In contrast, a syphilitic chancre is nontender and indurated (also see Syphilis). The identification of the causative agent of chancroid was first reported in 1889 by August Ducrey, following experiments in which he autoinoculated patients' forearms with pus from their genital ulcers.^{1, 2, 3} 

The Medscape CME course Global Burden of Sexually Transmitted Infections (Slides With Transcript) may be of interest.

Pathophysiology

H ducreyi produces a potent cytolethal distending toxin, which is an important virulence factor in the pathogenesis of chancroid, probably contributing to both the generation and the slow healing of ulcers.^{4 5}

Chancroid, or soft chancre, facilitates human immunodeficiency virus (HIV) transmission. The chemokine receptors CCR5 and CXCR4 belong to the class of 7 transmembrane G-protein–coupled receptors, and their natural ligands are key players in the recruitment of immune cells to sites of inflammation. CCR5 and CXCR4 are the 2 main co-receptors essential for HIV entry. Macrophages in chancroid lesions have significantly increased expression of CCR5 and CXCR4 compared with peripheral blood cells, and CD4 T cells have significant up-regulation of CCR5. The beta-chemokine RANTES (regulated on activation, normal T cell expressed and secreted) are important ligands for CCR5. RANTES is present throughout the papular and pustular stages of chancroid infection but is not present in uninfected control skin.⁶

Together with the disruption of mucosal and skin barriers, the presence of cells with up-regulated HIV-1 co-receptors in H ducreyi–infected lesions provides an environment that facilitates the acquisition of HIV-1 infection. Effective and early treatment of genital ulceration, and chancroid in particular, is an important part of any strategy to control the spread of HIV infection in tropical countries.⁷

Frequency

United States

Chancroid is rarely reported in the United States, but regional outbreaks and some endemic transmission occur, principally among migrant farm workers and poor inner-city residents.

International

Because of a lack of readily available, accurate diagnostic tests, the global incidence of chancroid is unknown. An estimated 6 million cases of chancroid occur each year. Chancroid is common in many of the world's poorest regions such as areas of Africa, Asia, and the Caribbean. These regions also have some of the highest rates of HIV infection in the world, and chancroid is common in all 18 countries where adult HIV prevalence surpasses 8%. In addition to regional outbreaks, individual cases are reported sporadically in the developed world, usually in individuals who have recently returned from chancroid-endemic areas or occasionally within the context of localized urban outbreaks, which may be associated with commercial sex work.

Mortality/Morbidity

• Chancroid produces painful ulcers on the genitals, often (50%) associated with unilateral tender inguinal lymphadenitis (ie, a bubo). Left untreated, the buboes can form fluctuant abscesses that spontaneously rupture, resulting in a nonhealing ulcer.
• Chancroid has been shown to be a major cofactor in the transmission of HIV-1 infection.⁸ This relationship has been especially significant in the heterosexual spread of HIV in Africa.^{7, 9}

Sex

Males develop chancroid most often, with a male-to-female ratio of 3-25:1.¹⁰

• Uncircumcised men develop chancroid more often than circumcised men.¹¹ Patients who are uncircumcised do not respond to treatment as well as those who are circumcised.^{12, 13}
• Chancroid is more common in heterosexual men.¹⁴
• Female prostitutes, either with active disease in the form of genital ulcers or as asymptomatic carriers, are an important reservoir for chancroid infection.

Age

Chancroid is most prevalent in sexually active and promiscuous males, with a mean patient age of 30 years.

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