Donovanosis is a chronic bacterial infection that causes slow-growing, painless ulcers on or around the genitals and anus. Also called granuloma inguinale, it is classified as a sexually transmitted infection, though it has notably low infectivity compared to other STIs. The infection is rare in developed countries but remains a concern in tropical and subtropical regions, particularly parts of India, Papua New Guinea, southern Africa, Brazil, and among Indigenous communities in Australia.
What Causes Donovanosis
The infection is caused by a bacterium called Klebsiella granulomatis. Once the bacteria enter the body, typically through small breaks in the skin during sexual contact, they invade immune cells in the tissue. Inside these cells, the bacteria multiply in clusters that are visible under a microscope. These clusters, known as Donovan bodies, are the hallmark of the disease and the key to confirming a diagnosis.
The incubation period is uncertain. Based on limited experimental data, it is estimated at roughly 50 days, but documented cases range anywhere from 1 day to a full year after exposure. This wide window makes it difficult to pinpoint exactly when infection occurred.
How Donovanosis Spreads
Sexual contact is the primary route of transmission, and infection rates are highest among adults between 20 and 40 years old. Women can develop lesions on the cervix, and men who have sex with men have a higher incidence of anal lesions, reflecting the sites of sexual contact involved. Poor hygiene and low socioeconomic status are additional risk factors.
That said, donovanosis doesn’t spread exclusively through sex. There are documented cases of fecal transmission, children infected through nonsexual contact such as sitting on an infected adult’s lap, and newborns infected during vaginal delivery. These cases are rare, but they complicate the picture of how the disease moves through communities.
What the Lesions Look and Feel Like
Donovanosis typically begins as a small, raised nodule on the genitals, perianal area, or groin. Over days to weeks, this nodule breaks open into an ulcer that slowly expands outward. The ulcer has a distinctive appearance: it is often described as velvety and granulating, with a beefy red surface. Unlike many other genital ulcers, donovanosis lesions are generally painless. They also tend to have an unpleasant odor.
One of the most useful distinguishing features is the absence of swollen lymph nodes in the groin. Many other STIs that cause genital ulcers, including syphilis, herpes, and chancroid, typically produce noticeable lymph node swelling. Donovanosis does not. This single detail can help narrow the diagnosis, especially in areas where the disease is uncommon and clinicians may not immediately recognize it.
How It Differs From Other Genital Ulcers
Several STIs cause sores in the genital area, and they can look similar at first glance. Here’s how donovanosis compares:
- Syphilis: Produces a single, painless ulcer (chancre) that feels firm or rubbery to the touch. Groin lymph nodes are usually swollen but not very tender. The sore heals on its own within weeks, unlike donovanosis, which keeps expanding.
- Herpes: Causes clusters of small, painful blisters on a red base, often accompanied by fever during the first outbreak. The pain alone usually distinguishes herpes from the painless ulcers of donovanosis.
- Chancroid: Produces shallow, painful ulcers with ragged edges and a red border. The ulcers are tender, and the groin lymph nodes are often swollen and painful.
- Lymphogranuloma venereum (LGV): Starts as a small papule or sore that often goes unnoticed. The hallmark is severely painful and swollen lymph nodes, sometimes draining through the skin.
The combination of painless, expanding, velvety ulcers with no lymph node involvement is what sets donovanosis apart from all of these.
How Donovanosis Is Diagnosed
There is no widely available blood test for donovanosis, and the bacterium is extremely difficult to grow in a laboratory. Diagnosis relies on taking a small tissue sample from the edge of the ulcer and examining it under a microscope. A special stain highlights the Donovan bodies, which appear as dark clusters packed inside large immune cells. Finding these inclusion bodies confirms the diagnosis.
Because the disease is rare in most parts of the world, it is often misdiagnosed initially as syphilis, cancer, or another condition. A biopsy is particularly important when a genital ulcer doesn’t respond to standard treatments or when it keeps growing despite antibiotics aimed at more common infections.
Treatment and Recovery
The CDC’s recommended treatment is an oral antibiotic taken either once weekly or daily for a minimum of three weeks. Treatment doesn’t stop at the three-week mark if the ulcers haven’t fully healed. The standard approach is to continue antibiotics until every lesion has completely resolved, which can take longer in advanced cases.
Most people begin to see improvement within the first week or two of treatment, with the ulcers gradually shrinking from the edges inward. However, healing is slow, and larger or older ulcers take considerably longer to close. Relapse is possible, particularly if treatment is stopped too early, so follow-up visits to confirm full healing are an important part of the process.
What Happens Without Treatment
Left untreated, donovanosis is a progressive disease. It does not resolve on its own. The ulcers slowly expand, destroying tissue over months and years, and the complications become increasingly severe.
The most common complication is genital lymphedema, a condition where damaged lymphatic pathways cause chronic swelling of the genitals. This occurs more frequently in women and results from the intense scarring that forms as ulcers heal and relapse repeatedly. Over time, this lymphatic damage can progress to elephantiasis, causing dramatic, permanent disfigurement of the vulva, penis, or scrotum.
Other complications include significant bleeding from the ulcers, scar tissue that fuses the scrotum to the penis, and narrowing of the urethral, vaginal, or anal openings. In long-standing cases spanning years, the chronic ulceration carries a risk of malignant transformation. Squamous cell carcinoma of the vulva has been reported in women with prolonged, untreated donovanosis. Any genital ulcer that has been present for a long time should be biopsied to rule out cancer.
In rare instances, particularly in people with weakened immune systems, the bacteria can spread through the bloodstream to distant organs. There are reports of infection reaching the liver, spleen, and bones, causing destructive lesions. This complication is exceptional but underscores why early treatment matters.