The West African state of Senegal became the fifth country to be touched by the world’s worst Ebola outbreak yesterday, while riots broke out in neighbouring Guinea where infection rates are rising fast.

The deadly virus has defied efforts by governments to control it, prompting the leading charity fighting the outbreak Medecins Sans Frontieres to call for the UN Security Council to take charge of efforts to stop the epidemic.

At least 1,550 people have died of Ebola and more than 3,000 have been infected since the virus was detected in the remote jungles of southeastern Guinea in March, and quickly spread across the border to Liberia and Sierra Leone.

Senegal is the fifth W. African country to confirm case

The World Health Organisation warned on Thursday the actual number of cases could be up to four times higher and said that a total of 20,000 people could be infected before the outbreak ends.

In the Guinean city of Nzerekore, riots broke out on Thursday night over rumours that health workers had infected people with the Ebola virus, a Red Cross official and residents said. A crowd of young men, some armed with clubs and knives, set up barricades across the southern city on Thursday and threatened to attack the hospital before security forces moved in to restore order.

Gunshots were fired and several people were injured, said Youssouf Traore, president of the Guinean Red Cross.

“A rumour, which was totally false, spread that we had sprayed the market in order to transmit the virus to locals,” Traore said. “People revolted and resorted to violence, prompting soldiers to intervene.”

Local Red Cross workers had to flee to the military camp with their medical equipment. Another resident said the security forces were preventing people leaving their neighbourhoods overnight. More than 400 people have died in Guinea, though the infection rate is slower than in neighbouring Liberia and Sierra Leone.

Senegal’s Health Minister Awa Marie Coll Seck said the country’s first case was a Guinean student who turned up for treatment at a hospital in the capital Dakar on Tuesday, concealing the fact that he had close contact with victims in his home country.

Authorities in Guinea had been searching for the young man for three weeks since he evaded surveillance, the minister said. Tests at the Pasteur Institute in Dakar showed him positive for the disease.

“We are tracing his whole itinerary and also identifying anyone who had contact with the patient who now that he has been diagnosed is much more cooperative and supplied all the necessary information,” the minister said.

In an attempt to prevent the spread of the virus, Senegal last week banned flights with three of the affected countries and shut its land border with Guinea.

Mego Terzian, head of the medical charity's French arm, said the epidemic was getting worse each day and neither MSF, the World Health Organisation (WHO) or the governments of Liberia, Sierra Leone and Guinea had the means to contain it.