Institute of Social and Preventive Medicine ISPM, University of Bern, Finkenhubelweg 11, 3012 Bern, Switzerland.
J Theor Biol. 2013 Aug 21;331:38-47. doi: 10.1016/j.jtbi.2013.04.010. Epub 2013 Apr 19.
Sexually transmitted infections (STIs) are, by definition, transmitted between sexual partners. For curable STIs an infected index case can potentially re-infect the same partner multiple times. Thus, R0, the average number of secondary infections one typical infected individual will produce during his or her infectious period is not necessarily the same as the average number of secondary cases (infected persons). Here we introduce the new concept of the case reproduction number (Rc). In addition, we define the partnership reproduction number (Rp) as the average number of secondary partnerships consisting of two infected individuals one typical infected individual will produce over his or her infectious lifetime. Rp takes into account clearance and re-infection within partnerships, which results in a prolongation of the duration of the infectious period. The two new reproduction numbers were derived for a deterministic pair model with serial monogamous partnerships using infection parameters for Chlamydia trachomatis, an example of a curable STI. We showed that re-infection within partnerships means that curable STIs can be sustained endemically even when the average number of secondary cases a person produces during his or her infectious period is below one.
性传播感染（STIs）根据定义是在性伴侣之间传播的。对于可治愈的 STIs，受感染的索引病例可能会多次重新感染同一伴侣。因此，R0 即每个典型感染者在其感染期间会产生的平均二次感染人数，不一定与平均二次感染人数（受感染者）相同。在这里，我们引入了新的病例繁殖数（Rc）的概念。此外，我们将伙伴关系繁殖数（Rp）定义为一个典型感染者在其整个感染期内产生的由两个感染者组成的二次伙伴关系的平均数量。Rp 考虑到了伙伴关系内的清除和再次感染，从而延长了感染期的持续时间。这两个新的繁殖数是针对具有连续一夫一妻制伙伴关系的确定性对模型推导出来的，使用了沙眼衣原体（一种可治愈的 STI）的感染参数。我们表明，伙伴关系内的再感染意味着即使一个人在其感染期间产生的平均二次感染人数低于 1，可治愈的 STIs 也可以在地方流行。
