為什麼愛滋感染者的猴痘病例發生率很高，這裡有3個理論

資料來源：PIEN HUANG / 2022 年 9 月 9 日 / 美國國家公共電台 (NPR) / 財團法人台灣紅絲帶基金會編譯 

 

新數據顯示，愛滋病毒陽性者感染猴痘的比例很高。上圖：用於 HIV 檢測的手指刺測試。

奇普索.莫德維拉/蓋蒂圖片社

 

最近幾個月，隨著猴痘病毒席捲歐洲、美洲和亞洲部分地區，研究人員發現了一個令人費解的趨勢：很大一部分猴痘病例發生在愛滋病病毒感染者身上。

上週發表在美國疾病控制與預防中心的《發病率和死亡率周刊》上的一篇新論文回顧了美國爆發前兩個月的 2000 例猴痘病例，發現近 40% 的病例發生在愛滋病毒感染者身上。這與歐洲疾病預防控制中心和世界衛生組織的衛生當局報告的情況相符——他們的數據顯示，大約 37-45% 的報告病例是在愛滋病毒感染者身上發現的。

那麼為什麼會有這麼多猴痘病毒感染者呢？健康專家有一個初步的想法來回答這個問題，然後是關於促成關鍵因素的三種理論——在其中有一個領先的競爭者。

這篇論文的合著者說，首先要考慮的是，目前的猴痘爆發主要集中在男男性行為人群中——「同志、雙性戀、同性戀」，美國疾病預防控制中心猴痘疫情應對首席醫療官Dr. John T. Brooks說。這些人群其就已經是處於感染愛滋病毒風險的人群。

但這本身並不能解釋高比率，布魯克斯說。例如，在美國，估計有 23% 的男男性行為者感染了愛滋病毒——但在研究分析的 2,000 名猴痘患者中，38% 的人感染了愛滋病毒。 「這部分[愛滋病毒感染者的猴痘病例] 非常地不同尋常」，他說。

理論 #1：猴痘在 HIV 傳播的同一社交網絡和性網絡中傳播

研究人員說，最大的影響因素可能與性網絡有關。猴痘與愛滋病毒一樣，透過性接觸傳播，它在同性戀、雙性戀和其他男男性行為者的各種網絡中傳播。

但關鍵是網絡，不一定是愛滋病毒狀況。白宮猴痘應對副協調員、研究合著者 Demetre Daskalakis 博士說：「我認為它更多地涉及性網絡，而不是[HIV 陽性] 血清狀態。性網絡 [在那裡] 我們看到猴痘感染正在發生」。”

其他人同意。 「猴痘的早期傳播與同性戀和雙性戀男性中的……文化活動——涉及性網絡的聚會和慶祝活動」有關，亞特蘭大的愛滋病毒醫生和研究員梅蘭妮湯普森博士說。根據疾病預防控制中心的說法，從國外聚會返回的人在美國播種了早期的猴痘病例，在美國，猴痘繼續「幾乎完全」透過性接觸在人與人之間傳播。

Thompson 說：「你只需要與一個人發生性關係或性行為就會感染猴痘」，但當猴痘在這些男男性行為人群中傳播的比在一般人群中多時，目前在男男性行為人群中感染猴痘的風險被放大了。

研究人員注意到的另一項統計數據是，研究人群中 41% 的猴痘患者近期有其他性傳播感染病史，例如衣原體、淋病或梅毒。布魯克斯說，這是一個重要的發現：「這說明這是一個性活躍的人群，透過密切、親密的接觸——在這種情況下，似乎是性接觸——有感染猴痘的風險」，布魯克斯說。

這意味著猴痘、愛滋病毒和性傳播感染具有重疊的風險因素，醫生應該注意所有這些因素，布魯克斯說：「如果你診斷出患有猴痘的人，你應該篩查愛滋病毒和性傳播感染。 相反，在尋求治療的有愛滋病毒和性傳播感染風險的人中，你需要想到猴痘並考慮為這些人進行評估。

理論 #2：也許 HIV 對免疫系統的影響會導致更多的感染？

這是一個懸而未決的問題：「感染和感染 HIV 是否會增加感染猴痘的風險」？埃默里大學的傳染病醫生和病毒學家 Boghuma Titanji 博士說，他指出 HIV 改變免疫系統的方式可能會增加一個人感染任何感染的風險。

在 CDC 研究中，許多感染 HIV 的猴痘患者感染控制良好——大多數人在過去一年接受了 HIV 治療，82% 的人受到病毒抑制，這意味著他們血液中的 HIV 水平很低甚至無法檢測到。這導致 Titanji 想知道 HIV 患者的總體風險是否會升高，而不僅僅是那些沒有接受治療的患者。

該研究還發現，8% 的 HIV 猴痘患者住院治療——略高於未感染 HIV 患者 3% 的住院率。不過，布魯克斯說，從數據中尚不清楚他們是否更有可能出現嚴重病例，或者他們的醫生是否更謹慎。他說：「我們現在沒有任何訊號顯示，愛滋病毒控制良好的人的情況比任何其他被診斷患有猴痘的人更糟」，[在此一研究中的愛滋病毒感染者] 均受到良好地照護，且治療的很好」。

Titanji 說，儘管如此，猴痘對於未經治療的 HIV 患者來說可能是非常危險的，他們經常免疫功能嚴重低下，也可能更容易延誤照護，尤其是在他們無法獲得健康保險或高質量照護的情況下。

理論#3：愛滋病毒患者可能會更頻繁地看醫生，因此更容易發現猴痘病例

Brooks 說，HIV 患者在猴痘病例中比例過高的另一個原因可能是「檢測偏差」。換句話說，攜帶愛滋病毒並為此服用藥物的人可能會定期去看醫生——他們的醫生可能會被提示要尋找猴痘。

Thompson 說：「這是一群最初願意照顧 HIV 感染者的照護提供者，但不幸的是，許多醫療提供者卻一直不願意看到患有猴痘的人，然而在 HIV照護中似乎並非如此，因此我們在這份報告中看到，非常高比例的 HIV 感染者實際上與醫療照護有關」，這可能意味著他們能夠在出現可疑皮疹的第一個跡象時接受檢測和治療。

儘管如此，猴痘患者的高 HIV 感染率不僅出現在美國，而且「全面」出現在歐洲和世界各地不同醫療保健系統的患者中，這顯示存在一種超出檢測偏差的模式，泰坦吉說。

最後說明：鑑於這些可能的原因，下一步是什麼？

確定 [HIV 陽性人群中猴痘發病率高] 的趨勢只是「冰山一角。它提出了很多問題」，Titanji 說。

布魯克斯和湯普森說，儘管行為似乎是關鍵原因，但還沒有足夠的信息來確定每個因素對這一趨勢的貢獻程度。

即便如此，知道猴痘和愛滋病毒以某種方式存在關聯，可以幫助將資源引導到可能產生最大影響的地方。 Daskalakis 在白宮的回應中表示，他們正在透過聯邦政府資助的 Ryan White HIV/AIDS 計畫分享猴痘指導並向 HIV 診所發送疫苗，他說該計畫為美國大約一半的 HIV 感染者提供醫療照護和支持。在美國他們還與資金和教育合作，將猴痘納入 HIV 和 STI 的照護流程中，「它所應歸屬地方」，Daskalakis 說。

未來的調查結果將有助於改進回應。「隨著我們的發展，我們將學到更多」，Daskalakis 說。儘管如此，可能需要一段時間才能確定有多少行為、生物學和偏見在推動這一趨勢，或者是否還有其他因素需要考慮。

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A high rate of monkeypox cases occur in people with HIV. Here are 3 theories why

PIEN HUANG / September 9, 2022 / NPR

 

 

New data shows a high instance of monkeypox among people who are HIV positive. Above: a finger prick test for an HIV test.

Chip Somodevilla/Getty Images

In recent months, as the monkeypox virus swept through Europe, the Americas and parts of Asia, researchers discovered a puzzling trend: A large proportion of monkeypox cases have been occurring in people with HIV.

A new paper, published last week in the CDC’s Morbidity and Mortality Weekly, reviews 2,000 monkeypox cases in the first two months of the U.S. outbreak and finds that nearly 40% are in people with HIV. That tracks with what health authorities from the European CDC and the World Health Organization have reported – their data show that around 37-45% of reported cases have been identified in people living with HIV.

So why are there so many monkeypox patients with HIV? Health experts have an initial thought to answer that question and then three theories on key contributing factors – with a leading contender among them.

The first thing to consider, says a co-author of the paper, is that the current monkeypox outbreak is largely concentrated among the population of men who have sex with men – “gay, bisexual, same gender-loving,” says Dr. John T. Brooks, chief medical officer for the CDC’s monkeypox outbreak response. And that’s the population that’s already at risk for HIV.

But that alone doesn’t explain the high rate, says Brooks. In the U.S., for example, 23% of men who have sex with men are estimated to be living with HIV – but among the 2,000 monkeypox patients whose data was analyzed in the study, 38% had HIV. “This fraction of [monkeypox cases in people with] HIV “is pretty extraordinary,” he says.

Theory #1: Monkeypox is circulating in the same social and sexual networks where HIV spreads

What’s likely the biggest contributing factor, say the researchers, has to do with sexual networks. Monkeypox, like HIV, spreads through sexual contact, and it’s circulating among various networks of gay, bisexual and other men who have sex with men.

But it’s the networks, not necessarily the HIV status, that are critical. “I think it speaks more to the sexual network and less for the serostatus [of being HIV positive],” says Dr. Demetre Daskalakis, deputy coordinator for the White House monkeypox response and a study co-author, “This is the social and sexual network [where] we’re seeing monkeypox infections happening.”

Others agree. “The early spread of monkeypox was associated with … cultural events – parties and celebrations that involved sexual networks” among gay and bisexual men, says Dr. Melanie Thompson, an HIV physician and researcher in Atlanta. People returning from parties abroad seeded early monkeypox cases in U.S., where monkeypox has continued to spread from person-to-person “almost exclusively” through sexual contact, according to the CDC.

“You only have to have sex, or be sexually active, with one person to get monkeypox,” Thompson says, but the risk of getting monkeypox is currently magnified in the population of men who have sex with men, where more monkeypox is circulating than in the general population.

Another statistic noted by the researchers is that 41% of monkeypox patients in the study population had a recent history of other sexually transmitted infections, such as chlamydia, gonorrhea or syphilis. This is a significant finding, says Brooks: “It speaks to the fact that this is a population that is sexually active, and through close, intimate contact – in this case, what appears to be sexual contact – are at risk for acquiring monkeypox,” Brooks says.

What it means is that monkeypox, HIV and sexually transmitted infections have overlapping risk factors, and doctors should look out for all of them, says Brooks: “If you diagnose someone with monkeypox, you should be screening for HIV as well as sexually transmitted infections. Conversely, among persons at risk for HIV and sexually transmitted infections who are seeking care, you need to think monkeypox and consider evaluating folks for that.”

Theory #2: Maybe HIV’s impact on the immune system leads to more infections?

It’s an open question: “Is there something about having and living with HIV that increases your risk for acquiring monkeypox?” says Dr. Boghuma Titanji, an infectious diseases physician and a virologist at Emory University, noting that HIV changes the immune system in ways that could increase a person’s risk of contracting any infections in general.

Many of the monkeypox patients with HIV in the CDC study have well-controlled infections – most had received HIV treatment in the past year and 82% were virally suppressed, meaning they had low to no detectable levels of HIV in their blood. That leads, leading to Titanji to wonder whether there’s an elevated risk for HIV patients in general and not just those that aren’t receiving treatments.

The study also found that 8% of monkeypox patients with HIV were hospitalized – somewhat higher than the 3% rate of hospitalization for those without HIV. Still, it’s not clear from the data whether they were more likely to have severe cases or if their doctors were being cautious, says Brooks. “We have no signal whatsoever right now that people who have well-controlled HIV are doing any worse than any other person who was diagnosed with monkeypox,” he says, “People with HIV [in the study] were generally receiving excellent care and doing well.”

Still, monkeypox can be very dangerous for patients who have untreated HIV, Titanji says – who are often seriously immunocompromised and may also be more likely to delay care, especially if they lack access to health insurance or high-quality care.

Theory #3: HIV patients may see doctors more often so monkeypox cases are more readily identified

Another reason why HIV patients are overrepresented among monkeypox cases could be “detection bias,” says Brooks. In other words, someone who’s living with HIV and taking medications for it probably sees a doctor regularly – and their doctor may be clued in to look for monkeypox.

“This is the group of care providers who initially were willing to take care of people with HIV,” says Thompson, “Whereas many providers, unfortunately, have been unwilling to see people with monkeypox, that seems not to be the case among HIV care providers. And so we see in this report that a very high proportion of people with HIV are actually linked to care,” which may mean they’re able to get tested and treated at the first sign of a suspicious rash.

Still, the fact that the high rates of HIV among monkeypox patients show up not just in the U.S., but “across the board” in patients in different health care systems in Europe and around the world, suggests there’s a pattern that extends beyond detection bias, says Titanji.

Final note: Given these possible reasons, what’s the next step?

Identifying the trend [of a high rate of monkeypox in the HIV positive population] is just “the tip of the iceberg. It raises a lot of questions,” Titanji says.

Even though behavior seems to be the key cause, there’s not enough information yet to figure out how much each factor contributes to the trend, Brooks and Thompson say.

Even so, knowing that monkeypox and HIV are linked in some way can help steer resources to where they could have the greatest impact. Daskalakis, with the White House response, says they’re sharing monkeypox guidance and sending vaccines to HIV clinics through the federally funded Ryan White HIV/AIDS program, which he says provides medical care and support to around half of people living with HIV in the U.S. They’re also working with funding and education to integrate monkeypox into the streams of care for HIV and STI’s, “where it belongs,” Daskalakis says.

Future findings will help refine the response. “We’re going to learn more as we go along,” says Daskalakis. Still, it could take a while to determine how much behavior, biology and bias are driving the trend, or whether there are other contributing factors yet to be considered.