The United States is closely monitoring the case involving a laboratory worker who died at a plague research institute in Siberia, Secretary of State Marco Rubio said on Monday (October 5).

A laboratory worker at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East fell ill and died in undisclosed circumstances, prompting authorities to quarantine dozens of ‌people, and the head of Russia's health watchdog to fly to the region.

There were conflicting reports about how and where the laboratory worker, whose age was given as 28, had fallen ill, but the authorities said she had died of pneumonia.

Rubio, citing what Russians have released about the death, said it seemed there was a worker in the lab who was infected and there was concern the disease may have spread internally.

Plague is endemic to Siberia, location of the first known prehistoric human outbreak, as the bacterium that causes it, Yersinia pestis, is present among the small wild mammals in its vast wilderness and their fleas. It is rare for Russians ⁠to fall ill with plague, however, though cases in other parts of the world - notably Africa - occur every year.

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Rubio says U.S. monitoring Siberia plague institute death

VIDEO SHOWS: U.S. SECRETARY OF STATE MARCO RUBIO SPEAKING TO MEDIA BEFORE HE TRAVELS TO ICELAND

RESENDING WITH FULL SHOTLIST AND SCRIPT

SHOWS: JOINT BASE ANDREWS, MARYLAND, UNITED STATES (OCTOBER 5, 2026)(U.S. NETWORK POOL - No use USA)

1. VEHICLES DRIVING U.S. SECRETARY OF STATE MARCO RUBIO ARRIVING AT JOINT BASE ANDREWS.

2. (SOUNDBITE)(English) U.S. SECRETARY OF STATE MARCO RUBIO, IN EXCHANGE WITH A REPORTER, SAYING:

REPORTER: "Can you give us an update on the suspected plague case in Russia?"

RUBIO: "Well, we know what we know, obviously, about whatever the Russians have provided, which it seems that there was a worker at the lab that was infected and there's concern that that, you know, could have spread, at least internally, you've seen them do quarantine of this and that nature. There's very limited travel between the U.S. and Russia, obviously. But like anything else, if something like that gets out, it can quickly spread. So we're watching and monitoring it closely. I don't think it's cause for alarm, but it is cause for focus and the cause to just keep an eye on it and we're doing that."

3. RUBIO WALKING UP THE STEPS TO THE PLANE ON HIS WAY TO ICELAND