Sexually transmitted infections (STIs) are rebounding in developed countries after being firmly in retreat for decades. The consequences can be devastating. Syphilis, for example, causes more than 200,000 stillbirths and infant deaths worldwide annually, and years later can lead to blindness, dementia or paralysis. The resurgence is a result of multiple factors including inconsistent condom usage and the abuse of illicit recreational drugs. At the same time, some common STIs, such as gonorrhea and shigellosis, are becoming harder to treat due to antibiotic resistance. In the U.S., which has the highest rates of sexually transmitted disease in the developed world, the crisis is costing an estimated $16 billion annually in preventable health-care expenses.

How bad is the problem?

In the U.S., cases of chlamydia, gonorrhea, and syphilis — three of the most common, treatable sexually transmitted diseases — jumped by more than 200,000 in 2017 to almost 2.3 million, a record. With syphilis, the annual rate of reported cases in the U.S. has almost doubled in recent years, to 31.4 cases per 100,000 people in 2017 from 15.9 per 100,000 in 2012. The trend with syphilis has also been seen in such countries as France, Belgium, Ireland and the U.K. In Australia, reported cases of gonorrhea climbed 63 percent from 2012 to 2016, while they surged sixfold in France and almost fivefold in Denmark from 2007 to 2016.

What’s driving that rise?

It’s complicated. Take syphilis: While the bulk of the roughly 6 million cases occurring annually are in low- and middle-income countries, some of the largest annual increases are in high-income countries. In these countries, syphilis has spread from some high-risk groups, such as gay and bisexual men, to the wider community. In the U.S., rates of early-stage syphilis among women surged 156 percent from 2013 to 2017. The Centers for Disease Control and Prevention says that’s associated with a corresponding rise in sexualized drug use — using methamphetamines or injection drugs, including heroin, to facilitate unprotected sex with multiple partners. Similarly in Europe, such practices, known as “party and play (PnP),” “chemsex” or “slamming,” have been shown to spur sex work and risky behavior, especially among men who have sex with men.

Are there other factors?

Yes. In the U.S., for example, the decline in AIDS mortality since the mid-1990s has been associated with a rebound in syphilis cases among men who have sex with men. More recently, the introduction of drugs to prevent HIV transmission — called pre-exposure prophylaxis, or PrEP — has shown great promise in reducing new infections among these men. It’s also been associated with less consistent use of condoms — one of the best means of protection against other STIs. More routine STI screening tests among PrEP users has made it difficult to know whether previously unrecognized and untreated infections are now being diagnosed or if there has been an actual increase. More international travel and labor migration also mean that germs are spreading faster and wider.

What are the consequences?

Each infectious agent presents its own particular dangers. For example, up to 40 percent of pregnancies with untreated syphilis result in miscarriage, stillbirth or early infant death. The surviving babies may suffer from abnormalities including skeletal defects, hearing impairment and meningitis, which can cause developmental delays and seizures. Reported cases of syphilis passed from a mother to her baby have more than doubled in the U.S. since 2013, reaching a 20-year high of 918 in 2017. Florida, California, Arizona, Texas and Louisiana accounted for 70 percent of cases. With chlamydia, 80 percent of infections are asymptomatic, yet even then it can be spread via sex. The infection is particularly serious for women. If untreated it may move to the upper reproductive tract, resulting in pelvic inflammatory disease. That can lead to ectopic pregnancy, chronic pain and infertility. Newborns may get pneumonia if they are infected in the uterus. Men with untreated chlamydia may develop arthritis.

How serious is drug-resistant gonorrhea?

Very. The bacterium has evolved to thwart multiple antibiotics, leading to four reported cases of extensively drug-resistant disease in the U.K. and two in Australia. While the bacterium is broadly susceptible to some newer antibiotics, these appear to be less effective at clearing the infection from the throat. Germs in the throat can spread surreptitiously via kissing, making them harder to stop. A key concern is that ceftriaxone, a backbone of treatment globally, is losing its potency, hastening the threat of untreatable gonorrhea. When the disease isn’t treated, it can cause infertility in both women and men, and potentially lead to a lethal bloodstream infection.

What can be done?

Experience has shown that encouraging condom use isn’t sufficient to curb infections. New tools and therapeutic agents, such as antiviral and antibiotic drugs, are needed. Vaccines, which have significantly reduced cases of human papillomavirus (HPV) and hepatitis B cases, could be an important defense. Research into vaccines against herpes and HIV is advanced, while those for chlamydia, gonorrhea, syphilis and trichomoniasis, another common STI, are in earlier stages of development.

What about the rest of the world?

Most of the more than 1 million people who catch a sexually transmitted infection each day are in low- and middle-income countries. Broadly, STIs are a barometer of access to health care: The worst rates occur in groups least likely to be tested and treated. The World Health Organization recognizes female sex workers, people who inject drugs, men who have sex with men, and transgender women as being most vulnerable. Faster and more-reliable testing at the point of care would make it easier to detect and treat infections earlier, especially in developing countries and remote areas.

在经历了数十年的稳步下降之后，性传播疾病（STI）在发达国家中出现了抬头迹象。这一现象带来的后果异常严重。例如梅毒，每年在全球都会引发超过20万例的死胎和婴儿夭折，而且婴儿在患病数年之后还会出现失明、痴呆或麻痹症状。性传播疾病的再度猖獗有多方面的原因，包括未能坚持使用避孕套以及非法消遣性药物的滥用。与此同时，由于抗生素耐药性的原因，包括淋病和志贺氏菌病在内的一些普通性传播疾病，正在变得越来越难治。在美国这个性传播疾病发病率最高的发达国家中，疾病的蔓延每年所消耗的可预防医疗费用达到了约160亿美元。

这个问题有多严重？

在美国，衣原体感染、淋病和梅毒这三种最常见、可治愈的性传播疾病在2017年大幅增加了20多万例，将患者总数推升至近230万。以梅毒为例，美国依据报道的年发病率在近些年来将近翻了一番，从2012年的15.9例/10万人增至2017年的31.4例/10万人。在法国、比利时、爱尔兰和英国，梅毒发病率也呈现出了类似趋势。在澳大利亚，2016年淋病发病率较2012年增长了63%。2007至2016年法国的发病率增长了5倍，丹麦的发病率增长了4倍。

增长的原因何在？

原因很复杂。以梅毒为例：尽管每年约600万例的新增病例都分布在中低收入国家，但高收入国家的增幅最高。在这些国家中，梅毒已经从一些高风险群体，例如同性恋和双性恋男士向更广泛的人群传播。在美国，2013-2017年，女性早期梅毒患病比例飙升了156%。美国疾病防控中心称，这一点与性化药物使用的上升有关，例如使用麻黄碱或注射海洛因之类的毒品刺激自身与多名伴侣发生不安全性行为。同样在欧洲，事实证明，称为party and play （PnP）、chemsex或slamming的类似活动成为了性工作和高风险性行为的推手，尤其是同性之间的性行为。

存在其他因素吗？

是的。例如在美国，20世纪90年代中期之后男同性恋群体艾滋病死亡率的下降一直伴随着梅毒病例的上升。最近，艾滋病传播预防药物（又称艾滋病暴露前用药或PrEP）的面世，完全有望降低这些男性群体中的新增病例数量。它还与不常使用避孕套有关，而避孕套是抵御其他性传播疾病最有效的方式之一。对PrEP使用群体进行更频繁的性传播疾病筛查测试会让人们难以弄清楚此前未发觉或未治疗的感染是否得到了确诊或实际上是有所增加。更加频繁的国际旅行和劳工迁移也意味着致病因子正在以更快的速度向更广泛地区传播。

有什么样的后果？

每一种致病因子都具有其独特的危险性。例如，在患有梅毒、且未得到治疗的孕妇中，出现流产、死胎或婴儿夭折的概率高达40%。存活下来的婴儿可能会出现畸形，包括骨骼缺陷、听力障碍以及会可能引发发育迟缓和癫痫的脑膜炎。自2013年以来，已报道的母婴传播梅毒病例在美国增长了一倍多，在2017年达到了20年来的新高——918例，其中70%的病例分布于佛罗里达、加利福尼亚州、亚利桑那州、得克萨斯州和路易斯安那州。以衣原体为例，80%的感染都没有什么症状，但它仍然可以通过性行为传播。这种感染在女性中尤为严重。如果不加以治疗，它可能会转移至上生殖系统，导致盆腔炎性疾病，继而引发子宫外孕、慢性疼痛和不孕。在子宫内被感染的新生婴儿可能会患上肺炎。支原体感染未得到治疗的男性可能会患上关节炎。

抗药性淋病有多严重？

非常严重。进化后的细菌已经能够对抗多种抗生素，英国和澳大利亚分别出现了4例和2例已报道具有广泛抗药性的淋病。虽然细菌对于一些新出现的抗生素普遍较为敏感，但喉部感染的治疗效果似乎要差一些。喉部的细菌可以在不经意间通过亲吻传播，也让这类感染难以杜绝。关键问题在于，全球性病治疗领域的主力军头孢曲松钠正在失去其效力，因此加剧了抗药性淋病出现的风险。当这种疾病无法得到治疗时，它可能会导致男性和女性的不孕不育，而且有可能导致致命的血液感染。

我们能做些什么？

经验告诉我们，鼓励使用避孕套还不足以抑制疾病的传播。我们还需要新工具以及包括抗病毒和抗生素在内的新治疗剂。疫苗也可以作为一个重要的防御手段，它曾经大幅降低了人乳头状瘤病毒和乙肝病例数量。对于皮肤疱疹和艾滋病疫苗的研究正在向前迈进，而针对支原体、淋病、梅毒和滴虫等其他常见性传播疾病的疫苗依然处于早期开发阶段。

世界其他地区是什么情况？

每一天都有100多万人感染性传播疾病，其中大多数都分布于中低收入国家。一般来说，性传播疾病是衡量医疗服务可获取性的一个指标：测试或治疗水平最差的群体有着最高的发病率。世界卫生组织发现，女性性工作者、注射毒品使用者、同性恋人群以及变性女性最容易受到感染。在医疗站点提供更快、更可靠的测试将有助于疾病的早期检测和治疗，尤其是在发展中国家和偏远地区。（财富中文网）

译者：冯丰

审校：夏林