The United States formally asked Russia for more information after the death of a laboratory technician at an institute studying plague, according to Le Monde with the Agence France-Presse (AFP).

The Centers for Disease Control and Prevention (CDC) say they are closely monitoring the situation and that, at the moment, nothing indicates a broader threat to the United States; the World Health Organization (WHO) assessed the risk as low for Russia and very low for Europe. Russian authorities say plague was not detected among the worker’s close contacts, according to NBC News.