Background: Pharyngeal gonorrhea is relatively common. However, the duration of untreated pharyngeal gonorrhea is unknown.
Methods: From March 2016 to December 2018, we enrolled 140 men who have sex with men in a 48-week cohort study. Participants self-collected pharyngeal specimens and completed a survey weekly. Specimens were tested using a nucleic acid amplification test at the conclusion of the study. We estimated the incidence and duration of infection. We defined incident infections as 2 consecutive positive tests, and clearance as 2 consecutive negative tests; and, after visual inspection of the data, we reclassified up to 2 weeks of missing or negative tests as positive if they occurred between 2 episodes of infections. We used Kaplan-Meier estimates to define duration of infection. Finally, we report on the frequency of single-positive tests and the time between the last negative test and the positive test.
Results: Nineteen (13.6%) of 140 participants experienced 21 pharyngeal infections (incidence, 31.7/100 person-years; 95% confidence interval, 20.7-48.6/100 person-years). The estimated median duration of pharyngeal gonorrhea was 16.3 weeks (95% confidence interval, 5.1-19.7 weeks). Twenty-two men had 25 single-positive specimens, a median of 7 days (interquartile range, 7-10 days) after their last negative test.
Conclusions: The median duration of untreated pharyngeal gonorrhea is 16 weeks, more than double previous estimates. This long duration of infection likely contributes to high levels of gonorrhea transmission.
Keywords: duration of infection; gonorrhea; natural history; pharyngeal.
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