KINSHASA, Congo -- No cases of Ebola have been detected among passengers on a river boat that was placed in quarantine near Kinshasa, health authorities have said.

The confirmation announced on Saturday eased concerns that the rare Bundibugyo virus might spread to the Congolese capital.

More than 200 boat passengers were placed in quarantine on Thursday in the port of Maluku, 65 kilometers (40 miles) from Kinshasa, after one traveler who was previously aboard the boat died with symptoms matching the Ebola virus.

Specialist teams from the Ministry of Health were deployed to Maluku to examine all of those on board. Those exhibiting suspicious symptoms had samples taken and sent to a laboratory for analysis, the ministry said on Saturday, adding that the vessel was also decontaminated.

The National Institute of Biomedical Research, which is responsible for testing, said that all suspected cases tested negative for Bundibugyo. It urged the population of Kinshasa to remain calm.

Congo has been battling an Ebola outbreak that has been deemed the fastest in history in terms of transmission, with confirmed cases since it started in May reaching 4,200, including over 1,900 deaths.

The river boat passenger had become sick and disembarked nearly three weeks ago in Pimu, in the province of Mongala, more than 1,000 kilometers from Kinshasa along the Congo River, Africa CDC Director-General Jean Kaseya said on Thursday. The capital has no confirmed Ebola case, he added.

News of the passenger’s death caused panic in Kinshasa, which is far from the eastern region hit by the outbreak, the second-largest outbreak on record, behind the 2014-2016 West Africa outbreak that recorded more than 28,000 cases, including over 11,000 deaths.

Ebola is highly contagious and spreads through contact with bodily fluids such as vomit, blood or semen, and with contaminated surfaces and materials such as bedding and clothing.

Health authorities say between 60% and 70% of new cases in the current outbreak are recorded outside of contacts being monitored, and that the outbreak is spreading at an “alarming” rate faster than efforts to track it.

The medical charity Doctors Without Borders said this week that the outbreak is still “spreading at an alarming and unprecedented rate” and that the response, which has been expanding, “is still not reaching communities quickly enough to break transmission chains.”