GOMA, Democratic Republic of Congo — The daughter of an Ebola patient in the eastern Congo city of Goma has contracted the virus, making her the third case in the city of one million which neighbors Rwanda, the government's Ebola response team said on Thursday.

The appearance of Ebola in Congo has raised concerns that the virus could spread across the border to Rwanda, which sealed its border with Congo on Thursday.

Rwandan state minister for foreign affairs ministry, Olivier Nduhungirehe, told Reuters by phone that the border had been shut at Rwanda's nearest town of Gisenyi but declined to give further details.

Confirmation of the third case in Goma increased fears the virus could take root in the densely populated city, which is more than 220 miles south of where the outbreak was first detected. The second case died after he sought treatment too late and was already bleeding, authorities said on Wednesday.

A woman gets her temperature measured at an Ebola screening station as she enters the Democratic Republic of the Congo from Rwanda in Goma on July 16. John Wessels / AFP - Getty Images file

"The tests on a suspected case at the Goma Ebola treatment center came out positive for the Ebola virus. Investigations are still underway around this... case," Dr Aaron Aruna Abedi, who coordinates the Ebola response for Congo's health ministry, told Reuters on the phone.

After the first Ebola case in Goma was confirmed in mid-July, the World Health Organisation (WHO) declared the outbreak an international health emergency. It was earlier reluctant to do so, partly out of fear countries bordering Congo might shut their frontiers.

When declaring the emergency, WHO director-general Tedros Adhanom Ghebreyesus said explicitly that no country should close borders or impose any travel or trade restrictions.

"The Congolese authorities deplore this decision, which runs counter to the advice of the WHO (World Health Organisation)," on fighting the virus, the Congolese presidency statement said.

The first Ebola case to hit Goma is not linked to the second or third, authorities say.