BHIVA: HIV-positive men presenting with repeated cases of syphilis infection in Manchester

The majority of men requiring treatment for syphilis reinfection in Manchester are HIV-positive, according to research presented as a poster to the Twelfth Annual Conference of the British HIV Association in Brighton between March 30^th and April 1^st

There have been outbreaks of syphilis, with a disproportionate number of cases involving HIV-positive gay men, in many western cities in recent years. Since 1999, almost 1100 cases of syphilis have been diagnosed in Manchester, with a significant number of patients being diagnosed with the infection on more than one occasion. In a retrospective study, investigators from the Manchester Royal Infirmary and the North Manchester Hospital examined the characteristics of patients presenting with syphilis reinfection in 2005.

A total of 34 individuals presented at Manchester’s NHS sexual health clinics with syphilis reinfection during the study period. All but four of the patients were from the UK, 33 were gay men, and 27 were HIV-positive.

Most men (22) were presenting with their second case of syphilis, but twelve men, eleven of whom were HIV-positive, were attending with their third case of syphilis infection.

Between them the 34 men with syphilis reinfection had had 80 episodes of the infection since the start of the Manchester syphilis epidemic in 1997, and other sexually transmitted infections were diagnosed at the same time of syphilis on 19 of these occasions.

They gathered basic information on the sexual behaviour of the men. High-risk sexual behaviour was defined by the investigators as more than three partners in the previous three months. A total of 55% of men with HIV met this definition of high-risk sexual behaviour, which may well be considered extremely conservative by some other investigators. The investigators did not present any data on the type of sexual behaviour the men engaged in. Other research into the Manchester syphilis epidemic has shown that oral sex was an important mode of transmission for the infection. Although syphilis can be readily transmitted by oral sex, it is thought that oral transmission accounts for a small number of HIV cases (current estimates are between 1% - 8%). The Manchester investigators diagnosed HIV at the same time as syphilis in two of the men with repeat syphilis infections, but some research has cast doubt on an automatic link between the epidemiology of syphilis and HIVresearch in California being an example.

Coinfection with HIV did not appear to compromise the efficacy of anti-syphilis therapy. A response rate of 89% was seen in HIV-positive patients when a single dose of intramuscular benzathine penicillin was used to treat syphilis and a 96% response rate was achieved when either three weekly intramuscular doses of benzathine penicillin or 17 days of intramuscular procaine penicillin were used. A cure rate of 88% was seen in HIV-negative patients.

“In this group of patients who have become reinfected with syphilis, HIV coinfection was highly prevalent”, conclude the investigators. They add, “safer sex messages should target HIV-positive gay men.”