Targeted Mass Treatment for Syphilis With Oral Azithromycin
March 27, 2003
British Columbia has had an outbreak of infectious syphilis since 1997, focused in a disadvantaged area of downtown eastside Vancouver. Forty-two percent of patients were associated with the sex industry, and the outbreak was propagated mainly through heterosexual contact. Only 6 percent of cases were homosexual men.Adapted from:
Targeted mass treatment appeared feasible because the people at risk were geographically concentrated and azithromycin was available for treatment. STD/AIDS prevention street nurses, part of a community-based outreach program, gave the intervention on two occasions over six consecutive days in January and February 2000, reaching 2,981 downtown eastside Vancouver residents ages 15-59, and 1,055 of the estimated 1,300-1,600 Vancouver sex workers. Those recruited were suspected sex workers, their customers, and those who admitted unprotected sexual contact. Outreach workers employed the secondary carry distribution method, encouraging participants to take medicine to their peers and sexual contacts. Syphilis cases fell for six months after the intervention, from February to July 2000, then returned to preintervention rates in September of that year. In 2001, syphilis cases increased substantially. The researchers performed curve fitting analyses and found that the number of cases in 2001 was higher than expected.
"The most probable explanation as to why the effect of targeted mass treatment was not sustained is that not enough of those at highest risk received treatment, and this highly vulnerable population was reinfected from within. The secondary carry method was used to reach these otherwise inaccessible people who are the main transmitters of the infection, but, although many pills were carried and no adverse effects were reported, this strategy probably failed to achieve its goal. For transmission of syphilis to be stopped, prevention efforts should be focused on groups of people at high risk of infection. Direct involvement of peers and the analysis of social network structures could improve targeted mass treatment efforts. Such [programs] also need a local mapping of syphilis cases and determination of the size and location of the population at risk. We do not plan another targeted mass treatment intervention and, unless the above prerequisites are in place we caution others against such an intervention," the authors concluded.
01.25.03; Vol. 361: 313-314; Michael L. Rekart; David M. Patrick; Bubli Chakraborty; Juanita J. L. Maginley; H. D. Jones; Chris D. Bajdik; Babak Pourbohloul; Robert C. Brunham
This article was provided by CDC National Prevention Information Network. It is a part of the publication CDC HIV/Hepatitis/STD/TB Prevention News Update.