Assessment of a geographically targeted field intervention on gonorrhea incidence in two New York state counties

Background and Objectives: Using study findings that demonstrated the impor tance of core group members in gonorrhea transmission, in 1984, one New Yor k State county changed its approach toward gonorrhea control by targeting i ts field intervention activities toward infected persons from a geographic core area. In late 1988, New York State experienced an epidemic increase in the number of syphilis casts. In response, the New York State sexually tra nsmitted disease (STD) control program enacted a Syphilis Initiative, which required the diversion of field staff from gonorrhea to syphilis control a ctivities for a 3-year period. Each of these events held the possibility of impacting gonorrhea incidence in this county. Goal of this Study: To evaluate the impact of core interventions on reducin g gonorrhea incidence as compared to traditional nontargeted field interven tion methods and to determine the influence on gonorrhea incidence of diver ting field activities from gonorrhea to syphilis case finding. Study Design: A Poisson regression method was used to estimate gonorrhea in cidence for a 22-year period in two similar counties: one county that used core intervention and one that applied traditional case-finding methods, Th e impact of core intervention was estimated in terms of the reduction in th e gonorrhea incidence rate from the preintervention incidence rates. Results: After initiation of the core intervention, the relative risk of go norrhea decreased by 61%. Between 30% to 40% of the total reported cases we re interviewed for contacts annually during the intervention period. In the control county, the relative risk was reduced by 50% despite a significant ly higher percentage of annual case interviews (60%-70%). In addition, a sm all change in the definition of core (from census tracts encompassing 50% o f gonorrhea cases to 30%-35%) during the Syphilis Initiative led to a signi ficant increase (16%) in the relative risk of gonorrhea. Conclusion: Targeting partner notification activities toward a geographic c ore area population appears effective in reducing the risk of gonorrhea, an d it was more efficient because the overall percentage of casts interviewed was smaller than in a county using a nontargeted approach. Diversion of st aff during a syphilis epidemic, combined with a narrowing of the geographic scope of the core intervention, was associated with an increase in gonorrh ea incidence.