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日益嚴重的mpox疫情促使世界衛生組織宣布全球衛生緊急狀態

非洲疾病管制與預防中心也發布了緊急聲明,因為一些國家出現了首例由猴痘病毒引起的疾病。

馬克斯‧科茲洛夫 / 2024 年 8 月 13 日 / 新聞 / 自然

一名護理師從一名疑似患有mpox的兒童身上採集了樣本。圖片來源:Arlette Bashizi/路透社即時訊息:世界衛生組織 (WHO) 於 8 月 14 日宣布,宣布 mpox 為「國際關注的突發公共衛生事件」—距離 WHO 上一次 mpox 緊急事件結束僅 15 個月。該項宣布亦要求世界各國共同努力,提供資源,以改善監測、治療感染者並阻止疫情爆發。

過去幾個月,一種令人擔憂的猴痘病毒株在中非迅速傳播。疫情的爆發促使非洲疾病管制與預防中心 (Africa CDC) 於 8 月 13 日宣布首次進入公共衛生緊急狀態,世界衛生組織 (WHO) 亦將於 8 月 14 日開會審議全球性聲明。

這些舉措反映了科學家們深切的擔憂,即由猴痘病毒引起的疫情爆發可能演變成一種流行病,蔓延到整個非洲大陸,甚至可能蔓延到更遠的地方。他們指出,這種病毒不僅在農村地區出現,而且在人口稠密的地區也令人震驚。

過去一個月,中部非洲的mpox感染激增,影響到包括剛果民主共和國 (DRC) 城市布卡武在內的地區,該城市擁有超過100萬居民,該區域亦有四個國家首次報告了mpox感染情況。這些感染可能與 2023 年底在剛果民主共和國南基伍省爆發的一場疫情有關,南基伍省是剛果民主共和國遭受人道暴力衝突蹂躪的地區。

由過去爆發的證據表明,在中部非洲傳播的病毒株比引發 2022 年全球 mpox 疫情的病毒株更具致命性,全球該次流行的病毒株已感染了 95,000 多人,並導致 180 多人死亡。

加州大學洛杉磯分校的流行病學家安妮·里莫恩 (Anne Rimoin) 說:「任何地方的感染都可能是所有地方的感染,我們已經多次看到這個想法的實現。」,她從2002年起一直致力於研究剛果的mpox 疫情。

稚嫩的年齡

非洲國家2024 年報告的確診和疑似mpox 感染病例數量已超過 2023 年全年:今年為 17,500 例,而 2023 年約為 15,000 例。兒童尤其容易受到傷害:剛果民主共和國約三分之二的感染者是 15 歲以下的人。其中一些感染可追溯到一種名為 clade II 的菌株,該菌株導致了 2022 年全球的疫情爆發。但在過去的幾個月裡,越來越多報告的感染病例歸因於一種名為第 I 型分支的菌株。數十年來,第I 型分支在中非引起了小規模疫情,通常僅限於少數家庭或社區。

今年4 月,研究人員分析了2023 年末和2024 年初在南基伍省收集的樣本後發現,他們發現了一種第I 型進化枝變體,稱為Ib 進化枝,它似乎透過性接觸等方式在人與人之間有效傳播。從那時起,該病毒已經傳播到人口稠密的地區(可能是由性工作者等流動性較高的人群攜帶)以及鄰國。南基伍省也正面臨人道危機,這使得追蹤和治療感染者變得更加困難,剛果民主共和國正在努力應對霍亂等其他疾病的嚴重蔓延。

蒲隆地、肯亞、盧安達和烏干達在過去一個月都報告了首例mpox感染,在8月初的一周內,剛果民主共和國報告了近2,400例疑似感染和56人死亡。這些事態發展促使位於亞的斯亞貝巴的非洲疾病預防控制中心之秘書長吉恩 · 卡塞亞 (Jean Kaseya) ,使用非洲聯盟 2023 年新授予的權力來宣佈公共衛生緊急狀態。

這次疫情的爆發也促使世界衛生組織召開會議,討論此次疫情是否值得宣布全球性緊急狀態,這會向世界各國發出信號,顯示可能需要進行協調和準備來控制該病毒。

神秘的病毒株

mpox 會導致充滿液體的皮膚損傷,這可能會導致疼痛,嚴重時甚至會導致死亡。目前尚不清楚 Ib 分支病毒的症狀是否與導致 2022 年疫情爆發的 II 分支病毒的症狀不同,以及它的危險性和傳播性到底有多大。 「這是一個事關百萬美元的問題,」里莫安說。

儘管已知mpox第 I型分支的死亡率高於 mpox第 II型分支,布卡武天主教大學傳染病流行病學家 Espoir Bwenge Malembaka 表示,這很難確定其原因。他說,除了病毒固有的毒力之外,許多因素也可能導致第I型分支的高死亡率:例如,歷史上曾有報道稱,第I型分支在該國醫療保健條件較差的農村地區出現過,這可能使其更加致命。

Bwenge Malembaka 說,迅速加強受影響國家之間的監測和合作將是控制疫情的關鍵。但是,許多高收入國家在 2022 年全球疫情爆發時所部署之針對 mpox 的治療方法和疫苗,在非洲國家卻仍然幾乎完全無法取得。

想要疫苗

這種情況可能很快就會改變:Kaseya在8 月8 日的新聞發布會上宣布,非洲疾病預防控制中心正在與總部位於丹麥的海勒魯普的Bavarian Nordic 生物技術公司進行談判,以獲得20 萬劑該公司的兩劑型mpox 疫苗。Kaseya補充說,但這與非洲疾病預防控制中心所估計在阻止當前疫情所需的 1,000 萬劑疫苗相去甚遠。

如果這些談判最終確定,仍有許多工作要做:很難將這些劑量運送到公共衛生基礎設施薄弱的地區,以及在感染性傳染病上具高風險的被污名化人群(例如性工作者和男男性行為者),Rimoin說道。此外,這些疫苗針對 Ib 分支的有效性尚不清楚,但考慮到中非的嚴峻形勢,Rimoin表示不應推遲獲得疫苗的計畫。

Rimoin 補充說,她希望在宣布任何緊急狀態後,高收入國家不會像 COVID-19 大流行和 2022 年 mpox 爆發期間那樣囤積疫苗和治療的藥物。她說:「至關重要的是要記住,我們控制疫情的最佳辦法是為出現和向外傳播風險最大的國家提供從源頭控制疫情所需的工具。」

doi:https://doi.org/10.1038/d41586-024-02607-y

參考文獻:
Vakaniaki,E.H.等。預印本於 medRxiv https://doi.org/10.1101/2024.04.12.24305195 (2024)。

Growing mpox outbreak prompts WHO to declare global health emergency

The Africa Centres for Disease Control and Prevention also issued an emergency declaration as several countries see their first cases of the disease caused by the monkeypox virus.

Max Kozlov / 13 August 2024 /  NEWS / Nature

A nurse takes a sample from a child suspected of having mpox.Credit: Arlette Bashizi/Reuters

Update: The World Health Organization (WHO) announced 14 August that it is declaring mpox a ‘public health emergency of international concern’ — just 15 months after the end of the WHO’s previous mpox emergency. The declaration asks the world’s countries to work together and to provide resources to improve surveillance, treat those who are infected and stop the outbreak.

A concerning strain of the monkeypox virus has spread rapidly across Central Africa in the past few months. The outbreak prompted the Africa Centres for Disease Control and Prevention (Africa CDC) to declare its first-ever public-health emergency on 13 August, and the World Health Organization (WHO) is meeting on 14 August to consider a global declaration.

The moves reflect scientists’ deep worry that the outbreak of mpox, the disease caused by the monkeypox virus, could evolve into an epidemic that spreads across the continent — and possibly beyond. They note that the virus is making an alarming appearance not just in rural regions, but also in densely populated areas.

During the past month, mpox infections have surged in Central Africa, affecting locations including Bukavu, a city in the Democratic Republic of the Congo (DRC) that has more than 1 million residents, and four countries in the region have reported mpox infections for the first time. These infections are probably connected to an outbreak that began in late 2023 in South Kivu province, a region of the DRC that has been ravaged by violent conflict.

Evidence from past outbreaks indicates that the viral strain spreading in Central Africa is more lethal than the strain that sparked the 2022 global mpox outbreak, which has since infected more than 95,000 people and killed more than 180.

“I hope that we’ve long gotten over the idea that something that is happening somewhere far away can’t affect us,” says Anne Rimoin, an epidemiologist at the University of California, Los Angeles, who has worked on mpox outbreaks in the DRC since 2002. “An infection anywhere is potentially an infection everywhere, and we’ve seen this idea come to bear many times.”

Tender age

African countries have already reported more confirmed and suspected mpox infections in 2024 than in all of 2023: 17,500 this year, compared with about 15,000 in 2023. Children are particularly vulnerable: around two-thirds of infections in the DRC are in people under the age of 15.

Some of these infections have been traced to a strain called clade II, which caused the 2022 outbreak. But over the past few months, an increasing proportion of reported infections have been attributed to a strain called clade I. Clade I has for decades caused small outbreaks in Central Africa, often limited to a few households or communities.

In April, researchers who analysed samples collected in South Kivu in late 2023 and early 2024 revealed that they had identified a clade I variant, called clade Ib, that seems to spread effectively between people through means including sexual contact. Since then, the virus has spread to densely populated areas, presumably carried by highly mobile populations such as sex workers, and to neighbouring countries. South Kivu is also confronting a humanitarian crisis that makes it harder to track and treat infected people, and the DRC is grappling with the aggressive spread of other diseases, such as cholera.

Burundi, Kenya, Rwanda and Uganda have all reported their first-ever mpox infections in the past month, and in a single week in early August, the DRC reported nearly 2,400 suspected infections and 56 deaths. These developments prompted Jean Kaseya, director-general of the Africa CDC in Addis Ababa, to use the power, newly bestowed by the African Union in 2023, to declare a public-health emergency.

The outbreak has also prompted the WHO to call a meeting to discuss whether the outbreak merits a global emergency declaration, which signals to countries worldwide that coordination and preparation might be necessary to control the virus.

Enigmatic viral strain

Mpox causes fluid-filled skin lesions, which can be painful, and, in severe cases, death. It is still unclear whether the symptoms of the clade Ib virus differ from those of the clade II virus that caused the 2022 outbreak, as well as precisely how dangerous and transmissible it is. “That’s the million-dollar question,” Rimoin says.

Can a smallpox drug treat monkeypox? Here’s what scientists know

Although the death rate for clade I mpox is known to be higher than that of clade II mpox, it is hard to pin down the reason, says Espoir Bwenge Malembaka, an infectious-disease epidemiologist at the Catholic University of Bukavu. Beyond the virus’s inherent virulence, many factors could be responsible for clade I’s high death rate: for example, clade I has historically been reported in rural parts of the country with poor access to health care, which could make it more lethal, he says.

Rapidly ramping up surveillance and cooperation between affected countries will be key to bringing the outbreak under control, Bwenge Malembaka says. But treatments and vaccines against mpox, which many high-income countries deployed in the 2022 global outbreak, continue to be almost totally unavailable to African nations.

Vaccines wanted

This might soon change: the Africa CDC is in negotiations with Bavarian Nordic, a biotechnology firm based in Hellerup, Denmark, to obtain 200,000 doses of the company’s two-dose mpox vaccine, Kaseya announced at a briefing on 8 August. But that’s a far cry from the 10 million doses that the Africa CDC estimates are needed to stop the current outbreak, Kaseya added.

If and when these negotiations are finalized, much work will still remain to be done: it will be difficult to deliver these doses to regions with poor public-health infrastructure, and to stigmatized populations that are at high risk of contracting mpox, such as sex workers and men who have sex with men, Rimoin says. In addition, the vaccines’ effectiveness against clade Ib is unclear — but, given the dire situation in Central Africa, Rimoin says that shouldn’t delay plans to obtain doses.

Rimoin adds that she hopes that any emergency declaration is not followed by the stockpiling of vaccines and treatments in high-income countries, as occurred during the COVID-19 pandemic and the 2022 mpox outbreak. “It’s critically important to remember that our best bet to control outbreaks is to provide the countries at greatest risk for emergence and spread outward to have the tools needed to control outbreaks at the source,” she says.

doi: https://doi.org/10.1038/d41586-024-02607-y

References

  1. Vakaniaki, E. H. et al. Preprint at medRxiv https://doi.org/10.1101/2024.04.12.24305195 (2024).
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