Authorities in Kazakhstan, Uzbekistan and Kyrgyzstan are increasing health screenings and other precautions after a suspected pneumonic plague case in Russia raised concerns about the potential spread of the deadly disease across the region.

The concern began in Siberia after 28-year-old Darya Shipilova, a laboratory worker at the Irkutsk Anti-Plague Research Institute, became seriously ill and died Oct. 2 after being hospitalized with pneumonia of unknown origin.

The case has drawn international attention because Shipilova worked at a facility dedicated to studying and preventing plague. Reports from independent Russian media have alleged that she accidentally broke a test tube containing pneumonic-plague bacteria while working at the institute on Sept. 25. Russian authorities have not confirmed that a laboratory accident occurred or that Shipilova was infected with plague.

Russia's public-health watchdog, Rospotrebnadzor, said extensive testing found no microorganisms associated with Shipilova's professional activities. The agency also said there had been no recorded incident involving pathogenic microorganisms at the institute. Authorities have instead described her illness as pneumonia of unknown etiology.

Despite those assurances, Russian officials have taken precautionary measures. People who came into contact with Shipilova have been identified and placed under medical observation, while part of the hospital in Shelekhov where she died was placed under quarantine. Russian officials have said no additional cases have been identified among employees of the anti-plague institute.

The situation has also drawn the attention of U.S. officials. The State Department said it is monitoring reports of a suspected fatal case of pneumonic plague in Russia in coordination with the Centers for Disease Control and Prevention and other agencies. U.S. officials have emphasized that many details remain unconfirmed.

Pneumonic plague is one of three forms of plague caused by the bacterium Yersinia pestis. Unlike bubonic plague, which is generally spread through infected fleas, pneumonic plague affects the lungs and can spread between people through respiratory droplets. The disease can become deadly rapidly if untreated, but antibiotics can be effective when treatment begins early.

The uncertainty surrounding the Russian case has prompted neighboring countries to increase their own precautions.

Kyrgyzstan has placed all sanitary-quarantine checkpoints along its borders on heightened alert. Officials are conducting additional epidemiological surveillance of people, vehicles and cargo entering the country, specifically citing reports surrounding the suspected dangerous infection in Russia.

Kazakhstan has also increased monitoring at its border crossings while tracking developments in Russia's Irkutsk region. Its health authorities have said no travelers with elevated temperatures, symptoms of illness or suspected particularly dangerous infections had been identified, and officials have assessed the immediate risk of importation as low.

Uzbekistan has similarly increased preparedness among its health and epidemiological services to prevent the importation and spread of particularly dangerous infections. Officials are monitoring information from Russian authorities and international health organizations as they assess the situation.

The border measures do not mean that a wider plague outbreak has been confirmed. At this point, there is no publicly confirmed evidence of widespread transmission in Russia or the three Central Asian countries. The precautions are being taken while authorities investigate how Shipilova became ill and continue monitoring those who may have been exposed.

For now, the central question remains whether the Russian laboratory worker's death was connected to plague at all. Russian health officials maintain that testing has found no evidence tying her illness to the pathogens handled at the institute, while reports of a possible laboratory accident have fueled concern well beyond Siberia.