Haemophilus ducreyi in genital ulcer disease: new developments in an old disease

Purpose of review Haemophilus ducreyi remains an important, though often overlooked, cause of genital ulcer disease (GUD), particularly in contexts where syndromic management limits pathogen-specific diagnosis. Although its incidence has markedly declined in high-income countries, the pathogen persists in resource-limited regions, where it is frequently co-endemic with Treponema pallidum and herpes simplex virus. A review is timely to synthesize new insights into its biology and clinical relevance. Recent findings Over the past two decades, the recognized epidemiological spectrum of H. ducreyi has expanded to include nonsexually transmitted cutaneous ulcers in children in tropical regions. Genomic and microbiological studies have clarified its population structure, revealing two major lineages with limited divergence between genital and cutaneous isolates. Advances in the characterization of virulence determinants and host–pathogen interactions provide an integrated view of its persistence, immune evasion, and ecological adaptability. Summary These developments have direct implications for the refinement of diagnostics, the optimization of therapeutic strategies, and the strengthening of surveillance systems in endemic areas. Revisiting the role of H. ducreyi in both genital and cutaneous ulcers is essential to anticipate its future public health impact.