Pre-exposure prophylaxis (PrEP) has been shown to be highly effective in reducing the risk of HIV infection in gay and bisexual men who have sex with men (GbMSM). However, PrEP does not protect against other sexually transmitted infections (STIs). In some populations, PrEP has also led to riskier behavior such as reduced condom usage, with the result that the prevalence of bacterial STIs like gonorrhea has increased. Here, we develop a compartmental model of the transmission of HIV and gonorrhea and the impacts of PrEP, condom usage, STI testing frequency and potential changes in sexual risk behavior stemming from the introduction of PrEP in a population of GbMSM. We find that introducing PrEP causes an increase in gonorrhea prevalence for a wide range of parameter values, including at the currently recommended frequency of STI testing once every three months for individuals on PrEP. Moreover, the model predicts that a higher STI testing frequency alone is not enough to prevent a rise in gonorrhea prevalence, unless the testing frequency is increased to impractical levels. However, testing every 2 months in combination with a 10–25 % reduction in risky behavior by individuals on PrEP would maintain gonorrhea prevalence at pre-PrEP levels. The results emphasize that programs making PrEP more available should be accompanied by efforts to support condom usage and frequent STI testing, in order to avoid an increase in the prevalence of gonorrhea and other bacterial STIs.

中文翻译：

---

人类免疫缺陷病毒暴露前预防对淋病患病率的影响

暴露前预防 (PrEP) 已被证明在降低男同性恋和双性恋男性 (GbMSM) 感染 HIV 的风险方面非常有效。但是，PrEP 不能预防其他性传播感染 (STI)。在某些人群中，PrEP 还导致风险更高的行为，例如减少安全套的使用，导致淋病等细菌性性传播感染的患病率增加。在这里，我们开发了一个 HIV 和淋病传播的区室模型，以及 PrEP 的影响、避孕套的使用、STI 检测频率以及在 GbMSM 人群中引入 PrEP 导致的性风险行为的潜在变化。我们发现引入 PrEP 会导致各种参数值的淋病患病率增加，包括目前推荐的对接受 PrEP 的个人每三个月进行一次 STI 检测的频率。此外，该模型预测，仅靠较高的 STI 检测频率不足以防止淋病患病率上升，除非检测频率增加到不切实际的水平。然而，每 2 个月进行一次检测，并结合 PrEP 个人风险行为减少 10-25% 将淋病流行率保持在 Pre-PrEP 水平。结果强调，使 PrEP 更容易获得的计划应该伴随着支持安全套使用和频繁 STI 检测的努力，以避免淋病和其他细菌性 STI 的流行率增加。该模型预测，仅靠较高的 STI 检测频率不足以防止淋病患病率上升，除非检测频率增加到不切实际的水平。然而，每 2 个月进行一次检测，并结合 PrEP 个人风险行为减少 10-25% 将淋病流行率保持在 Pre-PrEP 水平。结果强调，使 PrEP 更容易获得的计划应该伴随着支持安全套使用和频繁 STI 检测的努力，以避免淋病和其他细菌性 STI 的流行率增加。该模型预测，仅靠较高的 STI 检测频率不足以防止淋病患病率上升，除非检测频率增加到不切实际的水平。然而，每 2 个月进行一次检测，并结合 PrEP 个人风险行为减少 10-25% 将淋病流行率保持在 Pre-PrEP 水平。结果强调，使 PrEP 更容易获得的计划应该伴随着支持安全套使用和频繁 STI 检测的努力，以避免淋病和其他细菌性 STI 的流行率增加。