HCV在一对一异性伴侣间传播风险极低

加州大学旧金山分校的Norah Terrault医生及其同事在4月份的肝病学(Hepatology)杂志上报告，丙型肝炎病毒(HCV)在长期一对一的异性伴侣之间的传播风险极低，平均每年仅为1%。这一风险水平相当于传播率为每190,000次性接触发生1例(2013;57:881-9)。



该研究共纳入500例慢性HCV感染患者及其性伴侣。所有受试者均自称长期保持单一性伴侣的状态(中位持续时间为15年)；但关系持续时间的变化范围较宽，跨度为2~52年。分别对每对伴侣进行访谈，了解其性接触和实际情况。访谈时，患者的中位年龄为49岁，性伴侣的中位年龄为48岁。患者报告既往危险因素的发生率较高，包括1992年之前接受输血(32%)、注射非法药物(54%)和在医院内被染血的尖锐物体刺伤(4%)。接近一半(46%)的受试者报告一生中有≥20个性伴侣，21%报告有≥50个性伴侣。但伴侣也报告了一些危险因素：11%有早期输血史、2%使用了非法药物、2%有院内尖锐物体刺伤史。很多(27%)也报告至少有20个性伴侣。

结果显示，在500对受试者中，有20名性伴侣(4%)也感染了HCV。其中，9名为一致感染，8名为不一致感染，3名的情况不确定。6对一致感染伴侣接受了多基因分型，其中3对感染的是同一HCV分离株，另外3对感染的是不同病毒株。

对于3对感染相同病毒株的伴侣，研究者评估了传播时间和所有其他危险因素，发现第一对伴侣维持性关系18年，传播很可能发生于大约6.5年之后；女性伴侣曾使用注射药物，而男性无可识别的危险因素。第二对伴侣有28年的性关系史，传播很可能发生于第15年左右；女性伴侣曾使用注射药物，二人均报告既往性伴侣超过20个，有性传播疾病病史，并有吸食成瘾药物病史。第三对伴侣性关系持续10年，传播可能发生于第6年左右；女性伴侣曾使用注射药物，有在医院工作时被尖锐染血物体刺伤病史，并有20个以上的性伴侣；二人均报告吸食药物和共用吸食工具。研究者确定这些感染可能是性伴侣之间通过性接触传播的（患病率大约为1%）。

“每次性接触的估计风险范围为1/380,000~1/190, 000。”但仍无法确定可显著增加传播风险的行为。与无共同感染的伴侣相比，共同感染的伴侣更多在经期进行阴道性交（66% vs. 100%）、更多进行肛交（30% vs. 67%）、更少使用安全套（30% vs. 0%），但差异均不具有统计学意义。

研究者总结认为，在长期保持一对一关系的异性伴侣之间，慢性感染患者经性途径将HCV传播给性伴侣的机会极低。支持美国指南的建议，即一对一的异性伴侣不必改变性行为习惯。

作者均无相关利益冲突披露。

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By: MICHELE G. SULLIVAN, Ob.Gyn. News Digital Network

The risk of sexually transmitting a chronic hepatitis C infection to a long-term monogamous heterosexual partner is very low, averaging just about 1% per year.

That risk level works out to a transmission rate of about one in every 190,000 sexual contacts, Dr. Norah Terrault and her colleagues reported in the April issue of Hepatology (2013;57:881-9).

The cross-sectional study also found that no one sexual practice – including anal intercourse or intercourse during menses – significantly increased the risk of transmission, wrote Dr. Terrault of the University of California, San Francisco. The findings can be used to provide "unambiguous and reassuring counseling messages," she and her coinvestigators noted.

Hepatitis C is rarely transmitted between long-term monogamous heterosexual partners, said Dr. Norah Terrault.
 
The study included 500 subjects with chronic HCV infections, and their sexual partners. All couples reported longtime, monogamous relationships (median duration, 15 years); however, the relationship duration varied widely, spanning 2-52 years.

Each of the partners was interviewed separately about their sexual contacts and practices. At the time of interview, the index subjects were a median of 49 years old and the partners, a median of 48 years.

The HCV-positive subjects reported the highest incidence of past risk factors, including blood transfusions before 1992 (32%), injected illegal drugs (54%), and being stuck by a bloody sharp item in a hospital (4%). Nearly half (46%) reported having had at least 20 lifetime sexual partners, with 21% having had 50 or more.

However, partners also reported some risk factors: 11% had an early transfusion, 2% used illegal drugs, and 2% had a hospital sharps incident. Many (27%) also reported having had at least 20 sexual partners.

Among the 500 couples, 20 partners (4%) were coinfected with HCV. Of these, nine were concordantly infected, eight discordantly, and three were indeterminate.

Six of the concordant couples underwent phylogenetic typing. Three were infected with the same HCV isolate and three with different strains. The investigators estimated the time of transmission and any additional risk factor among the three couples with concordant strains.

For the first couple, with an 18-year relationship, transmission probably occurred after about 6.5 years. The female partner had a history of injected drug use, while the male had no identifiable risk factors.

The second couple had a 28-year relationship; transmission probably occurred at around 15 years, the investigators said. "The female partner had a history of injectable drug use and both partners reported more than 20 prior sexual partners, a history of sexual transmitted diseases, and a history of snorting of drugs."

For the third couple, who had been together for 10 years, transmission probably occurred at around year 6. "The male partner had a history of injectable drug use, of being stuck by a sharp bloody object while working in a hospital, and more than 20 prior sexual partners; both partners reported snorting drugs and sharing snorting equipment."

The investigators determined that these infections were probably sexually transmitted between the partners – a prevalence of about 1%. "The estimated risk per sexual contact ranged from 1/380,000 to 1/190, 000," they said.

However, they were unable to identify any behaviors that significantly increased the risk of transmission. Compared with couples without coinfection, coinfected couples were more likely to have vaginal intercourse during menses (100% vs. 66%), more likely to have anal intercourse (67% vs. 30%), and less likely to use condoms (0% vs. 30%), but none of these differences was statistically significant.

"HCV transmission by sex from chronically infected persons to their heterosexual partners in a long-term monogamous relationship likely occurs, but is a rare event," the authors concluded. "Our results provide a basis for specific counseling messages that clinicians can use with their patients... [that] support the current national recommendations that couples not change their sexual practices if they are in a monogamous heterosexual relationship."

None of the study authors reported any financial conflicts.