The U.S. Centers for Disease Control and Prevention on Thursday warned doctors and other healthcare workers about an outbreak of Ebola cases in Uganda.

The agency said although no cases have been reported in the U.S., it was issuing an advisory through its health alert network to raise awareness.

On January 29, a male nurse working in Uganda's capital, Kampala, died from Ebola caused by the Sudan virus. Uganda confirmed the outbreak on January 30.

The alert issued on Thursday is CDC's first since a temporary freeze on external communications was enforced by U.S. President Donald Trump's administration. Previous outbreaks of the Sudan virus have had a mortality rate of about 50%, the agency said.

The health alert network is CDC's primary method of sharing cleared information about urgent public health incidents with information officers, health practitioners, clinicians and health laboratories.

Ebola, a disease primarily affecting humans and nonhuman primates such as monkeys, chimpanzees and gorillas, is caused by a group of viruses. It spreads through direct contact with the body fluids of an infected person or one who has died from the disease.