Granuloma inguinale (donovanosis) represents a genital ulcerative disease of the skin and mucosa that is caused by the Gram-negative, intracellular bacterial pathogen Klebsiella granulomatis comb. nov. (also known as Calymmatobacterium granulomatis). In contrast to lymphogranuloma venereum and chancroid, this disease does not involve lymph nodes.

Knowing and understanding the epidemiology of the disease is important for undertaking prevention efforts; however, the causative microorganism is difficult to culture, thus the diagnosis often necessitates the visualization of dark-staining Donovan bodies (although molecular techniques have been becoming more pervasive in recent years).

Geographical Distribution

The disease is quite rare in the United States (US) and Europe, and is mostly seen in immigrants and returning travelers. On the other hand, granuloma inguinale is endemic in tropical and subtropical regions of the world, such as South Africa (especially in the provinces of East Transvaal and KwaZulu-Natal), Papua New Guinea, certain regions of India and Indonesia, but also among the Australian aborigines.

Furthermore, established donovanosis has been reported in Peru, Argentina, Brazil, Central America and the Caribbean, as well as French Guiana. It must be noted that during the last two decades the overall prevalence of this condition has decreased substantially, thus only sporadic cases are often seen – even in countries with high prevalence and disease endemicity.

Disease Incidence

Granuloma inguinale is usually considered as one of the minor sexually-transmitted diseases, as the prevalence is really low in Western Europe and the US. However, in India it accounts for up to 6.3% of all venereal diseases among the hospital population, and that number tends to be even higher in aforementioned countries.

The incidence of infection is greatest between 20 and 40 years of age, which is a period of sexual maturity. However, certain researchers have found a large number of cases in the age group between 11 and 30 years. Cases seen in children are usually a result of contact with adults that are infected, but not necessarily due to sexual abuse.

Even though earlier reports have shown a higher incidence of the disease in women, it seems men are more frequently affected nowadays. This condition has racial predilection for Afro-Americans, and is more common in those with deficient hygiene, as well as in people from a lower socio-economic status.

Epidemiological Characteristics

The main transmission pathway of donovanosis is a sexual intercourse, albeit direct contact and indirect contamination of genital region by fecal microbial flora are also considered as potential routes of infection (especially in children). Congenital infections (as a result of fetal infection) have not been reported in the medical literature.

Granuloma inguinale also has a highly variable incubation period, with an average of 17 days. Experimental production of full-blown lesions typical for this condition was successfully induced in volunteers 50 days after the inoculating the causative agent. The duration of disease may vary from six days to six years (the average being 152 days).

Moreover, granuloma inguinale increases the risk of acquiring human immunodeficiency virus (HIV) infection. For example, in Durban (a large city located on the east coast of South Africa) where HIV infection had been introduced quite recently, there was a surge in the proportion of men with concomitant donovanosis and HIV infection.