Majority of syphilis cases in Lyon involve HIV-positive patients

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The number of syphilis cases in the French city of Lyon increased 28-fold in 2002, with the majority of cases involving HIV-positive individuals, according to a letter published in the December 1st edition of the Journal of Acquired Immune Deficiency Syndromes.

Doctors at the Lyon University hospital wished to see if the recent increase in the incidence of syphilis observed in several European and US cities was also occurring in Lyon, and if so, what the characteristics of the patients infected with syphilis were.

Using the hospital laboratory database, the investigators found that no cases of syphilis were diagnosed in 1998, one case in 1999, none in 2000, with one case diagnosed in 2001. By September 2002, however, 28 new syphilis cases had been recorded, with 18 diagnosed in HIV-positive individuals.

Glossary

syphilis

A sexually transmitted infection caused by the bacterium Treponema pallidum. Transmission can occur by direct contact with a syphilis sore during vaginal, anal, or oral sex. Sores may be found around the penis, vagina, or anus, or in the rectum, on the lips, or in the mouth, but syphilis is often asymptomatic. It can spread from an infected mother to her unborn baby.

Gay men contributed two-thirds of the cases of syphilis in Lyon involving HIV-infected individuals.

Only 42% of the total number of syphilis cases involved gay men. This differs from the syphilis outbreaks in London, Manchester, and several other European and American cities where the overwhelming majority of cases have involved gay men, many of whom were also HIV-positive.

At the time of syphilis diagnosis, the Lyon HIV-positive patients had a median viral load of a little under 7,000 copies/mL, nine were taking HAART, and three had a viral load below 50 copies/mL. Median CD4 cell count was 416 cells/mm3.

In addition, the investigators established that a small number of patients with HIV and syphilis were also infected with hepatitis B or hepatitis C. Two patients (7%) were infected with HIV, syphilis and hepatitis C, and two with HIV, syphilis and hepatitis B.

Commenting on their findings, the investigators note that increased rates of sexually transmitted infections and unprotected sex have been recorded amongst HIV-positive individuals, particularly gay men. They speculate that the use of HAART and knowledge of viral load might be "falsely reassuring factors" and suggest that it would be worth investigating if HIV-positive individuals receiving HAART are over exposed to syphilis compared to HIV-positive patients who are not on treatment.

"It seems important", conclude the investigators, "to know whether patients with HIV had risky behaviours with partners who were HIV infected."

Further information on this website

Syphilis - overview

Syphilis - factsheet

References

Giard M et al. The recent increase in syphilis cases in Lyon University hospitals is mainly observed in HIV-infected patients: descriptive data from a laboratory-based surveillance system. JAIDS 34: 441 – 442, 2003.