Haemophilus ducreyi is a type of bacteria that causes a sexually transmitted infection known as chancroid. This infection is characterized by painful sores or ulcers on the genital area, which can lead to complications if left untreated. The bacteria are primarily spread through sexual contact, making it more common in areas with high rates of sexually transmitted infections. Diagnosis of Haemophilus ducreyi typically involves a physical examination and laboratory tests to identify the bacteria. Treatment usually includes antibiotics, which can effectively clear the infection. Preventive measures, such as practicing safe sex, can help reduce the risk of transmission.