Reinfections Make Up A Large Share of Gonorrhea Cases Diagnosed at Clinics
One-fifth of gonorrhea infections diagnosed in heterosexually active individuals during visits to two Baltimore public sexually transmitted disease (STD) clinics in 1998 were reinfections.1 Individuals receiving a gonorrhea diagnosis at an initial clinic visit between 1994 and 1998 had a risk of reinfection of about 4% per year, and half of first reinfections occurred within a year. The risk of reinfection was nearly twice as high among men as among women. Men had an elevated risk of reinfection if, at the initial visit, they reported having multiple sex partners in the prior month or having ever had a partner who exchanged sex for drugs or money; additionally, men aged 25 or younger had a higher risk than older men. Women had an increased risk of reinfection if they reported using condoms or having multiple sex partners in the prior month; their risk was reduced if they were visiting the clinic because they had had a partner who had an STD.
To assess the incidence of and risk factors for a first reinfection with gonorrhea, researchers analyzed data on 8,327 heterosexually active individuals aged 12 or older who visited the two clinics between January 1994 and October 1998, and who had at least one visit during which genital gonorrhea infection was diagnosed by culture. Sexual behavior, drug use and the reason for the visit were assessed at the initial visit. Reinfection was defined as another diagnosis of gonorrhea infection during a visit made at least three months after the initial visit.
More than 95% of individuals served at both clinics are black. Most of those included in the study were male (79%), and half were 25 or younger at the initial visit. The most common reason for visiting the clinic was symptoms of STD (83%). Only 10% reported using any condoms, and 42% reported having had two or more sex partners in the prior month. Sixteen percent reported ever having inhaled cocaine, and 7% reported ever having injected drugs. Overall, 4% had ever had sex in exchange for money or drugs, 7% had had sexual contact with someone who used injection drugs and 12% had had sexual contact with someone who engaged in exchange sex.
During 21,246 person-years of observation, a first reinfection occurred in 11% of individuals. Overall, four of every 100 individuals became reinfected per year, and half of these reinfections occurred within one year of the initial infection.
Between 1994 and 1998, the proportion of clinic visits for gonorrhea infection that were due to reinfection increased significantly (from 19% to 21%), and the average age at initial infection among individuals who became reinfected decreased significantly (from 28 to 23 years). During the same time period, there were significant decreases in the proportions of infected individuals reporting that they had ever injected drugs (from 8% to 5%), inhaled cocaine (from 20% to 14%) or had sexual contact with someone who engaged in exchange sex (from 13% to 10%).
In multivariate analysis of the study group overall, the risk of reinfection was significantly elevated for men (hazard ratio, 1.8) and for individuals who, at the initial visit, were aged 25 or younger (1.4), had had two or more sex partners in the prior month (1.2), used any condoms (1.6) and had ever had sexual contact with someone who engaged in exchange sex (1.5). The risk was significantly reduced for individuals who visited the clinic because they had had a partner with an STD (0.6), and the risk was marginally reduced for individuals who had ever injected drugs (0.8).
Three combinations of factors were also significantly associated with the risk of reinfection. The risk was increased more than sixfold for individuals who had ever engaged in exchange sex and visited the clinic as an STD contact (hazard ratio, 6.2). The risk was moderately increased for individuals who had ever engaged in exchange sex and had no reason recorded for their clinic visit (1.3), and for individuals who had had two or more sex partners in the prior month and had no reason recorded for their visit (1.7).
In sex-stratified multivariate analyses, women had an elevated risk of reinfection if they reported using any condoms (hazard ratio, 1.6) or having two or more sex partners in the prior month (1.6), whereas they had a reduced risk if they were visiting the clinic as an STD contact (0.6). Men had an elevated risk of reinfection if they were aged 25 or younger at first visit (1.5), had had at least two sex partners in the prior month (1.2) or had ever had sexual contact with someone engaging in exchange sex (1.5).
Commenting on the findings, the investigators note that reinfections account for a substantial proportion of all gonorrhea infections in this population. Moreover, they point out that because they did not have data on patients' STD history or on infections diagnosed at other facilities, they cannot determine whether individuals who tested positive for gonorrhea at only one visit had ever had another gonorrhea diagnosis. They stress that certain risk factors for reinfection present at the time of a first infection may help providers identify individuals who will benefit from preventive interventions. "Targeting interventions to people at risk for reinfection may be an effective way of maximally preventing gonorrhoea transmission and reducing resource utilisation," they conclude.--S. London
1. Mehta SD et al., Gonorrhoea reinfection in heterosexual STD clinic attendees: longitudinal analysis of risks for first reinfection, Sexually Transmitted Infections, 2003, 79(2):124-128.