Lymphogranuloma venereum (LGV; also known as climatic bubo, Durand–Nicolas–Favre disease, poradenitis inguinale, lymphogranuloma inguinale, and strumous bubo) is a sexually transmitted disease caused by the invasive serovars L1, L2, L2a, L2b, or L3 of Chlamydia trachomatis.

LGV is primarily an infection of lymphatics and lymph nodes. Chlamydia trachomatis is the bacterium responsible for LGV. It gains entrance through breaks in the skin, or it can cross the epithelial cell layer of mucous membranes. The organism travels from the site of inoculation down the lymphatic channels to multiply within mononuclear phagocytes of the lymph nodes it passes.

In developed nations, it was considered rare before 2003. However, a recent outbreak in the Netherlands among gay men has led to an increase of LGV in Europe and the United States.

LGV was first described by Wallace in 1833 and again by Durand, Nicolas, and Favre in 1913. Since the 2004 Dutch outbreak many additional cases have been reported, leading to greater surveillance. Soon after the initial Dutch report, national and international health authorities launched warning initiatives and multiple LGV cases were identified in several more European countries (Belgium, France, the UK, Germany, Sweden, Italy and Switzerland) and the US and Canada. All cases reported in Amsterdam and France and a considerable percentage of LGV infections in the UK and Germany were caused by a newly discovered Chlamydia variant, L2b, a.k.a. the Amsterdam variant. The L2b variant could be traced back and was isolated from anal swabs of men who have sex with men (MSM) who visited the STI city clinic of San Francisco in 1981. This finding suggests that the recent LGV outbreak among MSM in industrialised countries is a slowly evolving epidemic. The L2b serovar has also been identified in Australia.