South Sudan's Vice President Riek Machar and his wife Angelina Teny, who serves as defence minister, have tested positive for the coronavirus, his office said on Monday.
It said that "a number of his office staff and bodyguards" had also tested positive for COVID-19.
Machar said on state television that he would be in self-isolation for 14 days in his residence.
So far, South Sudan has recorded 347 cases of coronavirus and six deaths.
Last week authorities reported two COVID-19 cases in a camp outside the capital Juba, raising concerns among humanitarians that the infection could devastate the crowded settlement.
"We are particularly concerned that there have been a couple of cases that tested positive in the camp here just outside Juba. There are tens of thousands of internally displaced persons living there, so they live in quite cramped conditions," James Reynolds, from the International Committee of the Red Cross in South Sudan, said in a statement.
He added that measures such as social distancing and regular hand washing would not be easily applicable in the camp.