Chancroid is a bacterial infection that is spread by sexual contact with an infected person. Avoiding all forms of sexual activity is the only absolute way to prevent a sexually transmitted disease.
However, safe sex behaviors may reduce your risk. The proper use of condoms, either the male or female type, greatly decreases the risk of catching a sexually transmitted disease. You need to wear the condom from the beginning to the end of each sexual activity.
Murphy TF. Haemophilus infections. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 6th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2005:chap 222.
Eckert LO, Lentz GM. Infections of the lower genital tract: vulva, vagina, cervix, toxic shock syndrome, HIV infections. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 22.
Centers for Disease Control and Prevention, Workowski KA, Berman SM. Diseases characterized by genital ulcers. Sexually transmitted diseases treatment guidelines 2006. MMWR Morb Mortal Wkly Rep. 2006 Aug 4;55(RR-11):14-30.