Jan. 6, 2006 -- Oral sex raises the risk of a common sexually transmitted disease (STD) called nongonococcal urethritis (NGU) in men, Australian researchers report.
NGU is a type of urethritis, an infection of the urethra, the tube that carries urine from the bladder to outside the body. One of the most common causes is Chlamydia trachomatis infection, yet it is underreported because a substantial number of people are not aware of their infection and do not seek testing, according to the CDC.
Other less common bacteria and viruses can also cause NGU.
A significant number of men do not experience symptoms; this can contribute the continued spread of the STD.
NGU is common among men and women. The Australian study only included men.
Oral sex was linked to less common infectious causes of NGU in heterosexual men and men who have sex with men. The researchers include Catriona Bradshaw, MD, and colleagues.
Bradshaw works in Australia's Melbourne Sexual Health Centre and the University of Melbourne.
The study appears in The Journal of Infectious Diseases.
Bradshaw's study included 636 men -- 329 with and 307 without symptoms of NGU -- who were seen at the Melbourne Sexual Health Centre.
The men were about 32 years old, on average. They completed surveys about their sexual practices, gave urine samples, and got genital examinations. Those with NGU symptoms also got a urethral smear, a medical test done to detect pathogens that may cause the infection.
NGU was associated with receiving oral sex. It was also associated with unprotected anal sex and unprotected vaginal sex.
Several viruses were associated with NGU, including the herpes virus that causes cold sores (HSV-1). However, herpes sores weren't needed for NGU to spread. HSV-1 was strongly linked to giving oral sex and men who report having sex with men.
The HSV-1 virus was more strongly linked to NGU than another herpes virus, herpes simplex virus 2 (HSV-2).
The researchers couldn't always identify a virus that caused NGU. There may be viruses that cause NGU that haven't been discovered yet, they write.
Treatment decisions should be based on signs and symptoms associated with urethritis, not just tests done with a microscope, note Bradshaw and colleagues.
The study is "a good interim step in understanding this common and often frustrating syndrome," but more work needs to be done to understand NGU, writes editorialist H. Hunter Handsfield, MD.
Handsfield works in Seattle at the University of Washington's Center for AIDS and Sexually Transmitted Diseases, as well as the university's department of medicine.
The findings raise the importance of oral sex as a source of bacteria and viruses as the cause of this STD and indicate that we should broaden our search for other infectious causes of NGU, the researchers conclude.
SOURCES: Bradshaw, C. The Journal of Infectious Diseases, February 2006; vol 193: pp 336-345. WebMD Medical Reference from Healthwise: "Urethritis." Handsfield, H. The Journal of Infectious Diseases, February 2006; vol 193: pp 333-335. News release, Infectious Diseases Society of America.