Pneumonic plague, by the numbers

The World Health Organization said Wednesday that it had few clear answers about the recent death of a worker at a Russian institute that researched plague. The death, the subsequent isolation of hundreds of co-workers and close contacts, and reports that another worker may have pneumonia have fueled global concern about a rare form of plague.

Here’s what we know about pneumonic plague by the numbers.

One person who worked at the Irkutsk Research Anti-Plague Institute of Siberia in southeast Russia has died.

There have also been media reports that a second employee of the lab has pneumonia of “undetermined cause,” the director-general of the World Health Organization said Wednesday.

Igor Ivanko/AFP/Getty Images

Russia says no epidemic risk as WHO pushes for transparency on plague lab death

The 28-year-old who died was identified by the independent regional news outlet Lyudi Baikala as Darya Shipilova.

Shipilova first went to the hospital September 29 in Shelekhov, a town 12 miles southwest of Irkutsk, where she worked.

Three days later, on October 2 , she died.

Rospotrebnadzor, the Russian agency that handles infectious disease, says the worker died of pneumonia of “unknown” origin and downplayed suspicions that her death was related to her work.

WHO said it has seen about local media reports about an incident in the lab involving a broken test tube. Currently, “I know what you know from the media of the test tube breaking and exposure,” Dr. Maria Van Kerkhove, director of WHO’s department of Epidemic and Pandemic Management, said Wednesday.

On October 2 , the Russian government held a meeting “because they suspected a resident of the Irkutsk Institute had contracted a dangerous infection,” WHO Director-General Dr. Tedros Adhanom Ghebreyesus said Wednesday.

Checklists, masks and mystery: What we know about the plague scare in Russia

WHO said it first heard about the patient because it uses AI to monitor local news reports for illnesses of concern.

Under international law, Russia should have reported the incident within 24 hours .

After the WHO sought more information about the death, the Russian Federation replied Tuesday to say that that “ no case of plague had recently been reported.”

The Russian government also said it placed about 200 people who’d had contact with the worker in quarantine or under close follow-up , WHO said.

WHO said it had requested further information from the government, but has not received it.

“We don’t have the full picture of this event, and we are not able to conduct a full risk assessment,” Tedros said. “Timely, complete and transparent information sharing under the international regulations is essential to clarify conflicting reports and enable an accurate assessment of potential public health risks.”

Mystery death at Russian plague lab fuels backlash over transparency

A number of hospitals in the area have restricted visitors and are conducting comprehensive health checks, including requiring people to fill out questionnaires about “plague” and other infectious disease symptoms. Rospotrebnadzor, however, reassured people in the region where the lab operates that the “epidemiological situation” is stable.

About 95 people work at the Anti-Plague Institute.

The institute opened in 1934 to research plague. The bacterium that causes plague, Yersinia pestis, still circulates among wildlife in Siberia and neighboring regions.

The Irkutsk Anti-Plague Research Institute of Siberia and Far East/AP

Globally, more than 200 kinds of mammals, mostly rodents, can contract Y. pestis, studies show . Marmots are the most common carriers in Siberia.

WHO said the risk to the general public “appears to be low” at this time based on the limited information it has.

There are thousands of suspected plague cases around the world every year, Van Kerkhove said.

From 2019 to 2025, 10 countries reported almost 4,000 suspected human plague cases and 423 deaths , WHO said Wednesday.

Plague is among the deadliest bacterial infections in human history. Cases still happen today

Central Asia has the largest number of foci, or areas where the disease is present. People are most often infected after exposure to infected rodents.

There are four major types of plague caused by Y. pestis that attack different parts of the body:

Pneumonic plague is a rare, deadly lung infection. Scientists consider pneumonic plague the most dangerous form of the infection.

Bubonic plague, the most common form, often develops after a flea bite or when the bacteria enters through a cut or break in the skin. The infection triggers swollen, painful lymph nodes and can progress to septicemic plague.

Septicemic plague infects the bloodstream, potentially leading to organ failure. It can also come directly from a flea bite.

Pharyngeal plague attacks the throat after someone eats infected meat.

WHO said it conducted an initial assessment of risk based on an understanding that the Russian lab worker’s case could be pneumonic plague.

Pneumonic plague is the only form of the bacterial infection that can spread from person to person.

The basic reproduction number is about 1.1 to 1.3 , meaning that one person with pneumonic plague can spread the disease through a cough or sneeze to about 1.3 people , studies show . Droplets from infected animals can also transmit it.

Courtesy McMaster University or Museum of London Archaeology

Origins of plague could have emerged centuries before outbreaks, new study suggests

People can develop symptoms as soon as 24 hours after exposure, according to Dr. Rutul Dalal, an infectious disease physician at Penn State Health St. Joseph Medical Center. Typically, people with pneumonic plague are so sick that they rarely spread it because “it’s very difficult for someone to even walk, do their daily activities, let alone travel,” he said.

Centers for Disease Control and Prevention/Getty Images

There are no direct flights between Russia and the US, Dalal noted. By the time infected travelers reached the US, they would already be showing symptoms.

“Of course, you have to be careful,” he said, because “the world is a little village now,” as everyone learned during the Covid-19 pandemic.

Patients treated within the first 24 hours of infection have the best chance of surviving.

People with plague typically get at least 10 to 14 days of antibiotics.

Five antibiotics typically work best against plague: ciprofloxacin, levofloxacin, moxifloxacin, gentamicin and streptomycin.

Doctors have used plague vaccines since the 19th century , but it’s not clear how protective they are against pneumonic plague. WHO doesn’t recommend vaccination except for high-risk groups and lab workers who are regularly exposed to the bacteria.

The bacterium that causes plague circulates on every continent except Oceania.

It has infected human populations for at least 5,000 years , studies of archaeological sites show.

New analysis sheds light on mysterious source of Black Death

Three of the world’s deadliest pandemics were caused by Y. pestis.

The first known plague pandemic, from 541 to 750 , is known as the Plague of Justinian because it weakened Emperor Justinian’s attempts to reunite the Roman Empire, and some historians believe it contributed to the empire’s downfall. The pandemic probably began with fleas that bit rodents in Africa, and the disease raced along trade routes, killing up to 100 million people . Some historians believe that it killed half the population of the Mediterranean, although some contemporary historians say it may have been smaller than earlier historians believed.

The second plague pandemic, from 1347 through the 1700s and described by historians as the Black Death , probably originated in Central Asia and swept through Europe and the Middle East along trade routes. It wiped out about 30% to 60% of Europe’s population, an estimated 25 million to 50 million people, and is believed to have killed 75 million to 200 million globally.

The third plague pandemic, from 1894 to 1901 , began in China and traveled along trade routes by steamship, striking India and China hardest and killing 12 million to 15 million people , mostly in Asia.

Rijasolo/AFP/Getty Images/File

1924 was the year of the last documented person-to-person transmission of pneumonic plague in the US, during an outbreak in Los Angeles.

Since the 1990s, most human cases have been in Africa, according to WHO .

July 2025 was when the last person in the US died from pneumonic plague. The person lived in Arizona and was probably infected while working with sick cats. In the US about five human cases are reported every year.

世界卫生组织周三表示，对于近期俄罗斯一家研究鼠疫的研究所一名工作人员的死亡事件，目前尚无明确答案。这起死亡事件，以及随后数百名同事和密切接触者被隔离，再加上有报道称另一名工作人员可能患有肺炎，加剧了全球对这种罕见鼠疫的担忧。

以下是我们根据数据了解到的肺鼠疫情况。

一名在俄罗斯东南部西伯利亚伊尔库茨克抗瘟疫研究所工作的人员去世。

世界卫生组织总干事周三表示，媒体报道称，该实验室的第二名员工患有“病因不明”的肺炎。

伊戈尔·伊万科/法新社/盖蒂图片社

俄罗斯称不存在疫情风险，而世卫组织则敦促就鼠疫实验室死亡事件保持透明。

独立地区新闻媒体《柳迪拜卡拉》确认，死者为28岁的达里娅·希皮洛娃。

希皮洛娃于 9 月 29 日首次前往谢列霍夫镇的医院就诊，谢列霍夫镇位于伊尔库茨克西南 12 英里处，希皮洛娃在那里工作。

三天后，即10月2日，她去世了。

俄罗斯联邦消费者权益保护和福利监督局（Rospotrebnadzor）是负责传染病的机构，该机构表示，这名工人死于病因“不明”的肺炎，并淡化了外界对其死亡与工作有关的怀疑。

世卫组织表示，他们已注意到当地媒体报道了一起实验室试管破裂事件。世卫组织流行病和大流行病管理司司长玛丽亚·范·科霍夫博士周三表示：“目前，我所了解的情况与媒体报道的相同，即试管破裂和病毒暴露事件。”

世界卫生组织总干事谭德塞博士周三表示，10月2日，俄罗斯政府召开了一次会议，“因为他们怀疑伊尔库茨克研究所的一名居民感染了一种危险的传染病”。

清单、口罩和谜团：我们对俄罗斯的瘟疫恐慌了解多少？

世界卫生组织表示，他们之所以第一次听说这名患者，是因为他们利用人工智能监测当地新闻报道，以发现值得关注的疾病。

根据国际法，俄罗斯本应在24小时内报告该事件。

在世界卫生组织要求提供更多关于这起死亡事件的信息后，俄罗斯联邦周二回应称，“最近没有报告过鼠疫病例”。

世界卫生组织表示，俄罗斯政府还表示，已将约 200 名与该工人有过接触的人隔离或密切跟踪。

世界卫生组织表示，已要求政府提供更多信息，但尚未收到回复。

“我们尚未掌握此次事件的全貌，也无法进行全面的风险评估，”谭德塞说。“根据国际法规，及时、完整、透明地共享信息至关重要，这有助于澄清相互矛盾的报告，并准确评估潜在的公共卫生风险。”

俄罗斯瘟疫实验室神秘死亡事件引发公众对透明度的强烈质疑

该地区多家医院已限制访客，并开展全面的健康检查，包括要求人们填写有关“鼠疫”和其他传染病症状的问卷。然而，俄罗斯联邦消费者权益保护和福利监督局（Rospotrebnadzor）向实验室所在地区的民众保证，“疫情形势”稳定。

抗疫研究所约有95名员工。

该研究所成立于1934年，主要研究鼠疫。引起鼠疫的细菌——鼠疫耶尔森菌——至今仍在西伯利亚及其周边地区的野生动物中传播。

西伯利亚和远东伊尔库茨克抗鼠疫研究所/美联社

研究表明，全球有超过200种哺乳动物（主要是啮齿类动物）可以感染鼠疫耶尔森菌。在西伯利亚，旱獭是最常见的携带者。

世界卫生组织表示，根据目前掌握的有限信息，对公众的风险“似乎较低”。

范科霍夫说，全世界每年都有数千例疑似鼠疫病例。

世界卫生组织周三表示，从 2019 年到 2025 年，10 个国家报告了近 4000 例疑似人类鼠疫病例和 423 例死亡。

鼠疫是人类历史上最致命的细菌感染之一。时至今日，鼠疫病例仍然时有发生。

中亚地区是该疾病疫源地数量最多的地区。人们通常是在接触受感染的啮齿动物后被感染的。

由鼠疫耶尔森菌引起的鼠疫主要有四种类型，分别侵袭人体的不同部位：

肺鼠疫是一种罕见且致命的肺部感染。科学家认为肺鼠疫是鼠疫感染中最危险的一种。

腺鼠疫是最常见的鼠疫类型，通常由跳蚤叮咬引起，或细菌通过皮肤上的伤口或破损处进入体内。感染会导致淋巴结肿大、疼痛，并可能发展为败血性鼠疫。

败血性鼠疫会感染血液，可能导致器官衰竭。它也可能直接通过跳蚤叮咬传播。

咽喉瘟疫是指食用受感染肉类后侵袭咽喉的疾病。

世界卫生组织表示，他们根据对俄罗斯实验室工作人员的病例可能是肺鼠疫的了解，进行了初步的风险评估。

肺鼠疫是唯一一种可以在人与人之间传播的细菌感染形式。

基本传染数约为1.1至1.3，这意味着一名肺鼠疫患者通过咳嗽或打喷嚏可将疾病传播给约1.3人，研究表明。受感染动物的飞沫也可传播该疾病。

图片由麦克马斯特大学或伦敦考古博物馆提供

一项新研究表明，鼠疫的起源可能早在疫情爆发前几个世纪就已经出现。

宾夕法尼亚州立大学圣约瑟夫医疗中心传染病医生鲁图尔·达拉尔博士表示，人们最快可在接触病毒后24小时内出现症状。他指出，肺鼠疫患者通常病情严重，很少会传播病毒，因为“患者甚至难以行走、进行日常活动，更不用说旅行了”。

美国疾病控制与预防中心/盖蒂图片社

达拉尔指出，俄罗斯和美国之间没有直飞航班。感染病毒的旅客抵达美国时，往往已经出现症状。

“当然，你必须小心，”他说，“因为正如每个人在新冠疫情期间所了解到的那样，世界现在就像一个小村庄。”

感染后24小时内接受治疗的患者生存机会最大。

鼠疫患者通常需要接受至少 10 至 14 天的抗生素治疗。

五种抗生素通常对鼠疫最有效：环丙沙星、左氧氟沙星、莫西沙星、庆大霉素和链霉素。

自19世纪以来，医生们就开始使用鼠疫疫苗，但目前尚不清楚这些疫苗对肺鼠疫的保护效果如何。世界卫生组织建议，除高危人群和经常接触鼠疫杆菌的实验室工作人员外，不应接种疫苗。

引起鼠疫的细菌在除大洋洲以外的每个大陆都有传播。

考古遗址研究表明，这种病毒至少在5000年前就已感染人类。

最新分析揭示黑死病的神秘起源

世界上三次最致命的流行病都是由鼠疫耶尔森菌引起的。

已知最早的瘟疫大流行发生在公元541年至750年，被称为查士丁尼瘟疫，因为它削弱了查士丁尼皇帝统一罗马帝国的努力，一些历史学家认为它加速了帝国的衰落。这场瘟疫可能起源于非洲叮咬啮齿动物的跳蚤，并沿着贸易路线迅速蔓延，造成多达1亿人死亡。一些历史学家认为它夺去了地中海地区一半人口的生命，但一些当代历史学家认为实际死亡人数可能比早期历史学家估计的要少。

第二次鼠疫大流行，从1347年持续到18世纪，被历史学家称为黑死病，可能起源于中亚，并沿着贸易路线席卷欧洲和中东。它导致欧洲约30%至60%的人口死亡，估计有2500万至5000万人丧生，据信在全球范围内造成7500万至2亿人死亡。

第三次鼠疫大流行从 1894 年到 1901 年，始于中国，并沿着贸易路线乘汽船传播，对印度和中国造成了最严重的打击，导致 1200 万至 1500 万人死亡，其中大部分在亚洲。

里哈索洛/法新社/盖蒂图片社/文件

1924 年是美国最后一次有记录的人与人之间传播肺鼠疫的年份，当时洛杉矶爆发了疫情。

据世界卫生组织称，自 20 世纪 90 年代以来，大多数人类病例都发生在非洲。

2025年7月，美国最后一例肺鼠疫死亡病例发生。死者居住在亚利桑那州，很可能是在接触病猫时感染的。美国每年大约报告五例人类感染病例。