CNN) -- A health care worker at Texas Health Presbyterian
Hospital has tested positive for Ebola after a preliminary
test, the state's health agency said in a statement .
Confirmatory testing will be conducted by the Centers for
Disease Control and Prevention in Atlanta.

The employee helped care for Thomas Eric Duncan, the first
person diagnosed with Ebola in the United States . Duncan
died on Wednesday.

"We knew a second case could be a reality, and
we've been preparing for this possibility," Dr.
David Lakey, commissioner of the Texas
Department of State Health Services, said in a
statement Sunday morning.
"We are broadening our team in Dallas and
working with extreme diligence to prevent
further spread."

If confirmed by the CDC, the health care
worker's case would mark the second
diagnosis of Ebola ever in the United States.
Globally, the disease has wrought catastrophic
consequences.

The World Health Organization estimates more
than 8,300 have contracted Ebola during the
current outbreak. Of those, more than 4,000
people have died.
Three countries -- Sierra Leone, Guinea and
Liberia -- have been hardest hit.