喉嚨是男男性行為者中淋病感染的主要來源

 

喉嚨是男男性行為者中淋病感染的主要來源

資料來源:邁克爾.卡特,發佈時間:2019521日,aidsmap;財團法人台灣紅絲帶基金會編譯

根據發表於「性傳播感染」的澳大利亞研究報告,喉嚨是男男性行為者(MSM)中淋病傳播的主要來源。該研究涉及60名男性伴侶,並且在沒有尿道感染的情況下在咽喉和/或肛門中表現出高的淋病感染率。調查人員表示,由於接吻、口交、舔肛或使用唾液作為肛交的潤滑劑,傳播正在發生。

「我們的主要發現是,在沒有尿道感染的情況下,當一對伴侶中有人患有喉嚨淋病時,他的另一伴侶通常亦患有喉嚨淋病(23%),當一對伴侶中有人患有肛門淋病時,他的另一伴侶通常亦患有喉嚨淋病(34%)。「調查人員評論說,他們指出這些百分比遠高於預期中隨機發生的百分比(3-6%)。

他們補充說:「我們的數據與傳統的男性淋病傳播範例不一致,其中大多數淋病傳播是從尿道到咽喉和肛門,反之亦然。相反地,我們的數據與淋病傳播的新範例一致,其中喉嚨在向其伴侶的喉嚨、肛門和尿道傳播中扮演了核心角色,可能是透過受感染的唾液傳播。

如果正確的話,該研究的結果將具有公共衛生之意義,需要透過信息來解決唾液中的淋病傳播問題。

近年來,男男間性行為者的淋病罹患率顯著增加。預防策略的重點是進行肛交時使用保險套。尿道淋病的症狀包括陰莖尿道口有濃厚分泌物和排尿灼燒感,通常在感染後幾天內發生。在大多數情況下,這些令人不快的症狀會導致個案迅速尋求治療,從而限制了他們持續傳染的整體時間量。

男男間性行為者中淋病的高發生率和盛行率是否可能是由於喉嚨傳播所引起的,特別是因為該部位的許多感染是無症狀的?為了確定是否是這種情況,由Vincent Cornelisse博士領導的一組研究人員設計了一項包括了墨爾本性健康診所男男間性行為者伴侶的研究。

研究樣本包括60對伴侶(120名男性),伴侶中至少有一位被診斷患有淋病。通過NAAT(核酸擴增檢測)篩選診所的所有MSM的咽喉、肛門和尿道淋病。招募工作在2015年至2017年之間進行。

這些男性的中位年齡為30歲,並且診斷出有85個人感染淋病。喉嚨是最常見的感染部位(n = 63),其次是肛門(n = 48)和尿道(n = 25)。許多人都有多點感染,其中包括10名患者在所有三個部位都患有淋病的男性。

分別有8%和10%的患者報告了於插入性和接受性肛交時一致性地使用保險套。另有10%的男性報告最近沒有插入性肛交,11%的人表示他們沒有接受性肛交。

總共有25名男性患有尿道淋病,這些人當中有72%的伴侶患有喉嚨淋病,76%的伴侶患有肛門淋病。

伴侶其中任一人有喉嚨淋病(但沒有尿道感染)的總共有48對伴侶,其中包括11對伴侶(23%),其伴侶兩人都患有喉嚨淋病。由於排除了尿道淋病的男性,作者說尿道不太可能是感染源。

48名男性被診斷為肛門淋病。其中就有超過一半(52%)的伴侶患有喉嚨淋病。當調查人員排除同時感染肛門和尿道淋病的男性後,有34%患有肛門淋病的男性其伴侶患有喉嚨淋病。當他們排除了患有肛門淋病男性而其伴侶患有尿道淋病後,其餘患有肛門淋病男性中48%其伴侶患有喉嚨淋病。

在其中任何一人患有肛門淋病(但兩人都沒有尿道感染)的31對伴侶中,有15對伴侶(45%)其兩人都有肛門感染。當任一伴侶中的男性感染了喉嚨淋病的伴侶被排除之後,則只剩下了8對伴侶,其中包含一對兩者均患有肛門感染的伴侶。

「我們觀察到,如果一位男性其伴侶患有尿道淋病,則他亦會出現高的喉嚨和肛門淋病陽性率」,作者們指出。「在我們的研究中,大多數尿道淋病[88]是有症狀的,並且在出現症狀的幾天內就會出現在我們的診所。這表明這些伴侶中的淋病傳播方向可能是從喉嚨或肛門傳到尿道」。

作者聲稱,在肛門感染的男性伴侶中「相當程度」高盛行的喉嚨淋病感染- 即使是在排除了尿道感染的男性後- 也不支持傳統的觀點認為尿道是喉嚨和肛門淋病感染的主要來源。「相反地,這些數據支持從喉嚨到肛門的直接傳播」,作者評論道。

調查人員還特別強調,當一對伴侶中有一名男性患有喉嚨淋病時,這對伴侶中的兩個男人有很大的機會在在這個環境中受到感染。因此,他們認為傳播的發生係直接從喉嚨到喉嚨並透過接吻方式進行。

「我們的數據支持一種新的淋病傳播模式,這表明喉嚨是男性間淋病傳播的主要來源」,作者總結道。「公共衛生訊息可能需要討論性活動期間涉及唾液的淋病傳播風險。此外,目前正在研究的一種新型淋病預防策略是使用抗菌漱口水來減少喉嚨淋病的盛行率」。

來自同一研究團隊的第二項研究提供進一步的證據來支持這一假設。參加墨爾本診所的共有3,677名男男性行為者完成了調查,同時報告了他們過去三個月中性伴侶的數量:

他們平均曾經與4.3名伴侶親吻過但沒有口交或肛交。

他們平均曾經與5.0名伴侶有過性行為及親吻。

他們平均曾經與1.4個伴侶有過口交或肛交,但沒有親吻過。

僅只有接吻以及性與接吻併行者會與喉嚨感染淋病有關,但是只有性行為者則不會。對於有超過四個以上性伴侶但僅進行接吻行為的男性,調整後的喉部感染淋病的勝算比為1.46倍,而對有超過四個以上性伴侶且與性伴侶進行性行為並伴隨接吻行為的男性,其調整後的喉部感染淋病的勝算比為1.81倍。

The throat is a major source of gonorrhoea infections in MSM

Michael Carter ; Published: 21 May 2019, aidsmap

The throat is a major source of gonorrhoea transmission among men who have sex with men (MSM), according to Australian research published in Sexually Transmitted Infections. The study involved 60 male couples and showed a high prevalence of gonorrhoea infection in the throat and/or anus in the absence of urethral infection. The investigators suggest that transmission is occurring due to kissing, oral sex, rimming, or the use of saliva as lubricant for anal sex.

“Our key finding was that in the absence of urethral infection, when one man in a couple had throat gonorrhoea, his partner commonly had throat gonorrhoea (23%), and when one man in a couple had anal gonorrhoea his partner commonly had throat gonorrhoea (34%),” comment the investigators, who note these percentages are much higher than would be expected to occur by chance (3-6%).

They add: “Our data are not consistent with the conventional paradigm of gonorrhoea transmission between men, in which most gonorrhoea transmission is from the urethra to the throat and anus, and vice versa. Instead, our data are consistent with a new paradigm of gonorrhoea transmission in which the throat plays a central role in transmission to the partner’s throat, anus and urethra, presumably through infected saliva.”

If correct, the study’s findings will be of public health significance, requiring messaging to address gonorrhoea transmission in saliva.

Rates of gonorrhoea have increased significantly among MSM in recent years. Prevention strategies have focused on the use of condoms for anal sex. Symptoms of urethral gonorrhoea include a thick penile discharge and burning sensation when passing urine, typically occurring within days of infection. In most cases, these unpleasant symptoms will cause an individual to promptly seek treatment, therefore limiting the amount of time they remains infectious.

Could the high incidence and prevalence of gonorrhoea among MSM be due to transmission from the throat, especially as many infections in this site are asymptomatic? To see if this was the case, a group of researchers led by Dr Vincent Cornelisse designed a study involving MSM couples attending the sexual health clinic in Melbourne.

The study sample included 60 couples (120 men) in which at least one partner was diagnosed with gonorrhoea. All MSM at the clinic were screened for throat, anal and urethral gonorrhoea by NAAT (nucleic acid amplification test). Recruitment took place between 2015 and 2017.

The men had a median age of 30 years and gonorrhoea was diagnosed in 85 individuals. The throat was the most common site of infection (n = 63), followed by the anus (n = 48) and urethra (n = 25). Many individuals had multi-site infection, including ten men who had gonorrhoea in all three sites.

Consistent condom use for insertive and receptive anal sex was reported by 8% and 10% of patients respectively. A further 10% of men reported no recent insertive anal sex, with 11% saying they had had no receptive anal sex.

A total of 25 men had urethral gonorrhoea, of whom 72% had a partner with gonorrhoea in the throat and 76% had a partner with anal gonorrhoea.

There were 48 couples where either man had gonorrhoea of the throat (but neither had urethral infection), including eleven couples (23%) where both individuals had throat gonorrhoea. As men with urethral gonorrhoea have been excluded, the authors say that it is unlikely that the urethra is the source of infection.

Anal gonorrhoea was diagnosed in 48 men. Just over half (52%) had a partner with gonorrhoea in the throat. When the investigators excluded men with both anal and urethral gonorrhoea, 34% of men with anal gonorrhoea had a partner with gonorrhoea in the throat. When they excluded men with anal gonorrhoea whose partner had urethral gonorrhoea, 48% had a partner with throat gonorrhoea.

Of the 31 couples where either man had anal gonorrhoea (but neither had urethral infection), there were 15 couples (45%) where both men had anal infection. Couples where either man had infection in the throat were then excluded, leaving eight couples, including one where both men had anal infection.

“We observed high gonorrhoea positivity in the throat and anus if a man’s partner had urethral gonorrhoea,” note the authors. “Most cases of urethral gonorrhoea [88%] in our study were symptomatic and presented to our clinic within a few days of developing symptoms. This suggests that the direction of gonorrhoea transmission in these couples was likely from the throat or anus to the urethra.”

The authors assert that the “moderately” high prevalence of throat gonorrhoea among the partners of men with anal infection – even after excluding men with urethral infection – does not support conventional wisdom that the urethra is the main source of gonorrhoea infections in the throat and anus. “Instead, these data support direct transmission from the throat to anus,” the authors comment.

The investigators also highlight that when one man in a couple had throat gonorrhoea, there was a high chance that both men in the couple would have the infection at this site. They therefore suggest that transmission was occurring directly from throat to throat via kissing.

“Our data support a new paradigm of gonorrhoea transmission which suggests that the throat is a major source of gonorrhoea transmission between men,” conclude the authors. “Public health messaging may need to discuss the risk of gonorrhoea transmission during sexual activity that involves saliva. Also, a novel gonorrhoea prevention strategy is currently under investigation is the use of an antiseptic mouthwash to reduce the prevalence of throat gonorrhoea.”

A second study from the same research group provides further evidence to support the hypothesis. A total of 3677 MSM attending the Melbourne clinic completed surveys, reporting on numbers of sexual partners in the past three months:

§  mean 4.3 partners who they had kissed but not had oral or anal sex with

§  mean 5.0 partners they had kissed and had sex with

§  mean 1.4 partners they had had oral or anal sex with, but not kissed.

Kissing-only and kissing-with-sex were associated with gonorrhoea in the throat, but sex-only was not. The adjusted odds for gonorrhoea in the throat were 1.46-fold for men with more than four kissing-only partners and 1.81-fold for men with more than four kissing-with-sex partners.

Reference

Cornelisse VJ et al. Evidence of a new paradigm of gonorrhoea transmission: a cross-sectional analysis of Neisseria gonorrhoeae infections by anatomical site in both partners in 60 male couples. Sexually Transmitted Infections, online ahead of print 17 April 2019. doi: 10.1136/sextrans-2018-053803

Chow EPF et al. Kissing may be an important and neglected risk factor for oropharyngeal gonorrhoea: a cross-sectional study in men who have sex with men. Sexually Transmitted Infections, online ahead of print 9 May 2019. doi:10.1136/sextrans-2018-053896