NICE, FRANCE — An old nemesis appears to be the cause of a new outbreak of lymphogranuloma venereum proctitis.
The Chlamydia trachomatis L2b variant was thought to be a new strain when it was first identified as the major cause of the lymphogranuloma venereum (LGV) proctitis outbreak in homosexual men that began in the Netherlands in late 2003 and now occurs elsewhere in Europe, in Canada, and in the United States.
But recent findings suggest the C. trachomatis L2b variant was circulating among gay men in the 1980s in San Francisco and is appearing in large numbers as part of the overall increase in sexually transmitted diseases in this population, Julius Schachter, Ph.D., said at the 16th European Congress of Clinical Microbiology and Infectious Diseases.
“The obvious concern about LGV is that it's a systemic, more invasive disease that causes lots of tissue destruction and, because of the inflammatory component, was considered a potential risk factor for HIV transmission among gay men seen with the condition,” he said.
Chlamydiae were commonly recovered from rectal swabs from homosexual men with proctitis in San Francisco in the early 1980s. But the isolation rate dropped from about 33% to 6% in 1984–1985, suggesting that chlamydiae caused less proctitis as the gay community modified its behavior in response to AIDS, said Dr. Schachter, professor of laboratory medicine at the University of California, San Francisco. Throughout this time, about two-thirds of isolates were LGV.
After the recent outbreak began, serovar typing was performed on 51 archived specimens from San Francisco collected 20–25 years ago; 15 were identified as serovar L1, 18 as serovar L2, and 18 as the L2b variant (Emerg. Infect. Dis. 2005;11:1787–8).
New technologies, such as sequence-based nucleic acid testing, are useful in discriminating between LGV serovars and less invasive C. trachomatis species, he said.