Chancroid is a sexually-transmitted disease that is caused by the bacterial pathogen Haemophilus ducreyi. The condition is characterized by the presence of non-indurated, ulcerated lesions on the genitalia, usually associated with painful inguinal lymphadenopathy.
Chancroid is a substantial public health problem in many countries of the developing world. The estimates are that approximately seven million cases of this disease are seen worldwide; however, under-reporting and misdiagnoses hamper accurate predictions of its prevalence and spread.
Chancroid was once a common isolate in clinics across Africa, Latin America and Asia, where its incidence exceeded all other causes of genital ulcers combined. Nevertheless, after 2000 there was an extensive use of syndromic approaches for the management of sexually transmitted infections caused by bacterial pathogens, which resulted in a rapid decline of chancroid and its near-elimination in certain parts of southern and eastern Africa.
In sub-Saharan Africa, the overall prevalence of chancroid in patients with genital ulcers declined from more than 60 percent in the 1970s to less than 15 percent between 2001 and 2005. Moreover, the disease was undetectable in Zambia and Kenya between 2005 and 2010.
Although the disease is rare in the United States (US), outbreaks have been reported in urban areas. The case numbers are in decline since 1941, with only 24 documented in 2010, and 10 cases in 2013. But although the disease is considered infrequent in the US, it should be taken into account when assessing high-risk individuals presenting with painful genital ulcers.
The low prevalence of chancroid observed in Europe in the last two decades is linked to shifts in both public health and social conditions. Surveillance data has demonstrated Haemophilus ducreyi prevalence between 0.9 and 3 percent in ulcer patients from France and the Netherlands.
Since 2005, Haemophilus ducreyi has been implicated in chronic skin ulcers found in children residing in endemic areas for yaws (a chronic infection by the spirochete bacterium that affects bone, cartilage and skin) of the South Pacific region. Although similar to genital chancroid in appearance, this disease is not transmitted sexually, nor does it give rise to enlarged lymph nodes or bubo formation.
Age, Sex and Racial Differences
Chancroid is most commonly seen in non-white, uncircumcised individuals (which is not surprising considering its endemic prevalence in areas of Asia, Africa and Latin America). Circumcision has been shown protective against chancroid infections, but also for some other sexually transmitted diseases (such as syphilis and human immunodeficiency virus).
The transmission probability from an infected individual to an uninfected one is estimated as 0.35 for a single sexual exposure. The main issue is that in women ulcers tend to be subclinical, resulting in continuous sexual activities and frequent contacts that are needed for the spread of Haemophilus ducreyi within a population.
This disease is usually observed in commercial sex workers, travelers that visited endemic areas, and generally in people of lower socioeconomic standard. Furthermore, chancroid may affect individuals of any age, although it is usually found in younger, sexually-active individuals (aged between 21 and 30 years).
In any case, chancroid is not lethal, and the genital lesions tend to resolve spontaneously after 1-3 months – even if they are left untreated. However, if antimicrobial therapy is not instituted, suppuration of inguinal lymph nodes may ensue, which can even progress to rupture and formation of non-healing inguinal ulcer.