了解疫情控制的關鍵——烏干達的蘇丹病毒病（註）
資料來源：Armand Sprecher，醫學博士，公共衛生碩士 / n engl j med nejm.org / 財團法人台灣紅絲帶基金會編譯
2022 年 9 月 20 日，烏干達政府宣布穆本德區爆發蘇丹病毒病 (SVD)。 截至11月5日，已確診SVD病例132人，其中死亡49人； 其他 21 人死於 9 月 20 日之前開始的疾病，被認為可能患有 SVD。 疫情已蔓延至其他六個地區，包括首都坎帕拉。
蘇丹病毒與伊波拉病毒一樣，屬於絲狀病毒科，其中包括其他四種也會導致人類疾病的病毒：本迪布焦病毒、泰森林病毒、馬爾堡病毒和拉文病毒 (Bundibugyo virus, Taï Forest virus, Marburg virus, and Ravn virus)。 不幸的是，烏干達曾爆發過所有這些病毒引起的疾病，但 Taï Forest 病毒除外，迄今為止僅在一個人身上發現過這種病毒（在象牙海岸）。與伊波拉病毒不同，蘇丹病毒和任何其他絲狀病毒均尚未成為成功治療或疫苗的目標，儘管開發此類介入措施的計畫正在進行中。
第一次烏干達絲狀病毒爆發發生在 2000 年，包括 425 例 SVD。 本迪布焦病毒病的第一次爆發發生在 2007 年，其中包括 131 例病例。其他 8 次爆發的規模要小得多（15 例或更少），這可能是由於較早發現或烏干達在管理此類爆發方面的專業知識不斷增加。
儘管烏干達爆發了大大小小的疫情，但都沒有達到 2013-2016 年西非伊波拉病毒病 (EVD) 爆發的嚴重程度，這是烏干達最大的絲狀病毒病 (FVD) 規模的近 100 倍暴發。儘管公共衛生專家曾希望針對伊波拉病毒的有效疫苗和療法的出現能夠避免再次發生此類事件，但 2018 年至 2020 年在剛果民主共和國東部爆發的伊波拉病毒病疫情最終總計達 3,841 例，持續了 2 年。多年來，儘管有疫苗和治療方法——已經對這一假設提出了質疑。為什麼我們仍然爆發涉及數千例的病例？小的突發變大的一個主要原因是人們搬家。絲狀病毒病 (FVD) 主要透過社交網絡傳播，因為大多數人在為病人（通常是親戚或朋友）提供照護時或透過參加 FVD 死者的葬禮時被感染。當 FVD 暴發發生在孤立的農村時，通常會發生的是動物流行病之溢出，它們很少會蔓延很遠，因為村莊居民的社會關係通常在空間分佈上受到限制。但當它們到達城市時，爆發會變得更大，那裡的醫院為來自無數社交網絡的人們在一個地方一起工作提供照護。在住院期間被感染的患者和在提供照護時被感染的醫護人員返回家中並將疾病傳播給朋友和家人。
然而，今天，非洲的道路基礎設施比以前更好，而且更多人可以負擔得起交通費，因此家庭網絡遍及更廣泛分散的城市和村莊。FVD 疫情沿著連接這些家庭的同一條道路傳播，就像在西非 EVD 疫情開始的幾內亞、賴比瑞亞和獅子山的共同邊界發生的那樣。這些道路也為在遙遠的地方人們提供了尋求經濟機會的途徑，這些人可能會攜帶正在潛伏的病毒——這就是西非伊波拉病毒病暴發，從距離 400 英里外的 Guéckédou 發現第一例病例僅兩週後，如何快速到達幾內亞科納克里的原因。
FVD 的潛伏期估計為 2 至 21 天； 平均時間各不相同，但通常在 6 到 10 天左右，這讓受感染的人有時間在生病之前走很遠的路，前提是他們有辦法和動力這樣做。在過去的十年中，方法變得更加普遍，所以也許背景動機值得檢驗。
居住在 FVD 爆發地區的人們不僅有普通的旅行理由——例如工作和探親——而且爆發本身提供了額外的理由。家人生病或去世，遠方的親戚會前來幫忙照顧或參加葬禮。這些親屬可能將潛伏的疾病帶回家。此外，患有重病的人通常會在經濟能力範圍內尋求最好的治療，即使這需要前往較遠的轉診醫院。在疫情爆發期間，受感染者通常會向住在別處的家人尋求庇護，以努力向鄰居隱瞞病情（以避免相關的社會恥辱）或衛生當局（避免被迫前往治療機構）。所有這些動作導致了更大規模的爆發。
了解面臨 FVD 爆發的人群對於規劃可能擴大的流行病很重要，但對於爆發控制的其他方面也至關重要。生活在 FVD 爆發地區的人們具有在傳染病頻繁發生的環境中形成的文化習俗和信仰； 這種做法可能不僅包括照顧病人和埋葬死者，還包括傳統醫學。這些行為可以促進絲狀病毒的傳播，而且它們通常根深蒂固，不易改變。 疫情應對機構在尋求改變時，需要了解人們行為的社會和文化決定因素。2000 年烏干達 SVD 暴發的管理，因暴發應對小組不了解當地的健康觀念而錯失了將他們的風險溝通與民眾對疾病傳播的理解相結合的機會。這來之不易的教訓 (hard-won lesson) 促使人類學家定期加入應對小組，以協助設計和實施控制措施。
然而，理解需要雙向——受疫情影響的社區也需要理解響應者。醫療和公共衛生響應人員要求受影響社區的成員避免去進行一些行為，但對他們卻是有意義的行為，例如照顧生病的親人和在葬禮期間觸摸死者；並做一些會嚇著他們的事情，例如進入治療設施——因為許多患者無法從那裡活著出來。如果我們不能成功地解釋開發有效疫苗和療法的過程，它就會被視為邪惡的實驗，而不是試圖提供幫助。
如果衛生專家希望人們採納我們的建議、接受我們提供的服務並參與疫情控制，我們首先需要獲得他們的信任——這是一個經常被忽略的步驟。病例調查組、接觸者追踪組、疫苗接種組、埋葬組、去污組輪流走訪每個村莊，沒有一個熟悉的人會停下來解釋，這是怎麼一回事。以自我瞭解方式急於建立治療中心和監測系統，安全埋葬死者，並培訓醫護人員安全地照顧病人，反應小組往往推遲了最重要的事情：在控制爆發時讓他們試圖幫助的人此一最有價值的合作夥伴參與提供援助。這種脫節破壞了迄今為止幾乎所有對疫情的控制。
烏干達當局最近決定派出一個單一的多學科團隊對 SVD 熱點提供綜合響應，而不是派出多個獨立的團隊各自為戰。這種方法提供了一個機會，可以向社區提供一個單一的聯繫點，可以在應對疫情的人和受其影響的人之間建立關係，從而實現相互理解和建立信任，使響應者和社區成員作為合作夥伴一起工作——也許可以防止另一次小規模爆發蔓延。
作者提供的披露表可在 NEJM.org 獲取。
來自比利時布魯塞爾無國界醫生組織。
本文於 2022 年 11 月 16 日發表在 NEJM.org。
註：此文所指之蘇丹病毒病 (SVD) 係指到目前仍無有效疫苗或抗病毒藥物治療、也無法快篩，相對罕見的伊波拉病毒蘇丹（Sudan）株。
Understanding the Key to Outbreak Control — Sudan Virus Disease in Uganda
Armand Sprecher, M.D., M.P.H. / n engl j med nejm.org
On September 20, 2022, the government of Uganda declared an outbreak of Sudan virus disease (SVD) in the Mubende District. As of November 5, SVD cases had been confirmed in 132 people, 49 of whom had died; 21 other people had died from illnesses that began before September 20 and were considered probable SVD. The outbreak has spread to six other districts, including the capital, Kampala.
Sudan virus, like Ebola virus, belongs to the family Filoviridae, which includes four other viruses that also cause disease in humans: Bundibugyo virus, Taï Forest virus, Marburg virus, and Ravn virus. Uganda has the unhappy distinction of having had outbreaks of disease caused by all these viruses except Taï Forest virus, which has been found in only one human (in Ivory Coast) so far. Unlike Ebola virus, neither Sudan virus nor any of the other filoviruses has yet been targeted by successful treatments or vaccines, though plans for developing such interventions are under way.
The first Ugandan filovirus outbreak occurred in 2000 and consisted of 425 cases of SVD. The first outbreak of Bundibugyo virus disease, which included 131 cases, occurred in 2007. Eight other outbreaks have been much smaller (15 or fewer cases), perhaps owing to earlier detection or to Uganda’s growing expertise in managing such outbreaks.
Although Uganda has had more than its share of outbreaks big and small, none have approached the magnitude of the West African Ebola virus disease (EVD) outbreak of 2013–2016, which was nearly 100 times the size of Uganda’s largest filovirus disease (FVD) outbreak. Although public health experts once hoped that the advent of effective vaccines and therapeutics for Ebola virus would make another such event unlikely, the EVD outbreak in the eastern Democratic Republic of Congo in 2018–2020 — which ultimately totaled 3841 cases and lasted for 2 years, despite the availability of vaccines and therapeutics — has called into question this assumption. Why did we still have outbreaks involving thousands of cases?
A major reason that small outbreaks become big is that people move. FVDs are transmitted primarily through social networks, since most people become infected while providing care to sick people, often relatives or friends, or by participating in funeral ceremonies for those who have died from an FVD. When FVD outbreaks occur in isolated rural villages, where epizootic spillover typically happens, they rarely extend far because the social relationships of village inhabitants are usually limited in their spatial dispersal. Outbreaks become large when they reach cities, where hospitals provide care for people from myriad social networks together in one location. Patients who become infected while hospitalized, and health care workers who become infected while providing care, return to their homes and spread disease to friends and family.
Today, however, Africa has better road infrastructure than it once did, and transportation is affordable for more people, so family networks extend across more widely dispersed cities and villages. FVD outbreaks spread along the same roads that connect these families, as happened at the shared borders of Guinea, Liberia, and Sierra Leone, where the West African EVD outbreak began. These roads also provide a means for people to pursue economic opportunities in distant locations, and these people can potentially bring incubating virus along with them — which is how the West African EVD outbreak arrived in Conakry, Guinea, only 2 weeks after the first case was detected in Guéckédou, 400 miles away.
The incubation period for FVD is estimated to be 2 to 21 days; the average varies, but is often around 6 to 10 days, which allows people who have been infected the time to travel a long way before becoming ill if they have the means and motivation to do so.4 In the past decade, the means have become more commonly available, so perhaps motivation bears examination.
Not only do people who live where FVD outbreaks occur have ordinary reasons to travel — such as employment and visiting family — but outbreaks themselves provide additional reasons. Illness or death in the family brings relatives from afar to aid with caretaking or to attend funerals. These relatives may bring incubating disease back home. In addition, people with severe illness generally seek out the best care within their economic means, even if that requires travel to a referral hospital some distance away. During outbreaks, infected people commonly seek refuge with family living elsewhere, in an effort to conceal illness from their neighbors (to escape the associated social stigma) or from health authorities (to avoid being pressured into going to a treatment facility). All this movement has resulted in larger outbreaks.
Understanding the people facing FVD outbreaks is important in planning for the possible expansion of an epidemic, but it is vital for other aspects of outbreak control as well. People living where FVD outbreaks occur have cultural practices and beliefs that have evolved in an environment where infectious diseases occur frequently; such practices may include not only care of the sick and burial of the dead but also traditional medicine. These behaviors can facilitate filovirus transmission, and they generally have deep roots and are not easily modified. Outbreak-response agencies need to be aware of the social and cultural determinants of people’s behavior when they seek to change it. Management of the SVD outbreak in Uganda in 2000 was complicated by the fact that the outbreak-response team did not understand the local health beliefs and missed an opportunity to align their risk communication with the population’s understanding of disease transmission. This hard-won lesson has led to the regular inclusion of anthropologists in response teams to aid in designing and implementing control measures.
Understanding needs to go both ways, however — communities affected by an outbreak need to understand the responders as well. Medical and public health responders ask members of affected communities to refrain from behaviors that are meaningful to them, such as caring for loved ones who are ill and touching the deceased during funerals, and to do things that may frighten them, such as entering a treatment facility — from which many patients do not emerge alive. If we do not successfully explain the process of developing effective vaccines and therapeutics, it is seen as nefarious experimentation rather than an attempt to help.
If health experts expect people to take our advice, accept the services we offer, and participate in outbreak control, we first need to gain their trust — a step that is too often omitted. It’s hard to build relationships when each village is visited in turn by a case investigation team, a contact tracing team, a vaccination team, a burial team, and a decontamination team, none of which include a single familiar person who will stop and explain what’s going on. In their understandable haste to set up treatment centers and surveillance systems, safely bury the dead, and train health care staff to safely care for patients, response groups too often defer what is most important: engaging the assistance of the most valuable partners in outbreak control, the people they are trying to help. This disconnect has undermined control of nearly every outbreak to date.
The Ugandan authorities recently decided to send a single multidisciplinary team to provide an integrated response to SVD hotspots, rather than sending multiple separate teams to operate in silos. This approach provides an opportunity to present the community with a single point of contact from which a relationship may be built between the people responding to the outbreak and those affected by it that would allow for mutual understanding and building of trust, enabling responders and community members to work together as partners — and would perhaps prevent another small outbreak from becoming large.
Disclosure forms provided by the author are available at NEJM.org.
From Médecins Sans Frontières, Brussels.
This article was published on November 16, 2022, at NEJM.org.