The Democratic Republic of Congo said late Sunday that the number of confirmed cases of Ebola in the country has risen to 1,873, including 672 deaths.

Earlier Sunday, the United States advised its citizens to avoid all travel to the Democratic Republic of Congo due to the Ebola outbreak, after a second American relief worker was infected while participating in efforts to combat the worsening outbreak in the country, according to Bloomberg.

The U.S. Embassy in Kinshasa clarified in a health alert issued Saturday that travelers exposed to the Ebola virus are required to undergo quarantine outside Congo for up to 21 days at their own expense.

The alert noted that the U.S. government will provide life-saving medical assistance to citizens exposed to the virus, but did not specify whether these guidelines include humanitarian workers or medical teams already deployed in the country.