The arrival of the missionary on Thursday night at Carlos III Hospital. G. A. / getty

Four people who were admitted to hospital in Madrid and Tenerife on Thursday over fears they may have contracted Ebola have all tested negative for the virus after initial blood tests.

Two people were put in isolation in Madrid’s Carlos III Hospital on Thursday, while a third arrived shortly after midnight. The three new patients in Madrid are a person who was transported in the same ambulance as Spain’s only confirmed Ebola case, Teresa Romero; a Nigerian man who arrived in Madrid on a flight from Paris yesterday, having started his journey from Lagos; and a Spanish missionary who had been working in Liberia.

According to government sources cited by news agency EFE, the first tests have come back negative, although the patients will remain at the hospital for a 72-hour period under observation. José Manuel Echevarría, the head of virology at the National Microbiology Center at the Carlos III Health Institute, reported that the Nigerian man has tested positive for malaria.

On Friday morning it was announced that the patient in Tenerife, a Red Cross nurse who was working with Ebola cases in Sierra Leone, had also tested negative for the virus but, like the Nigerian plane passenger, was found to be suffering from malaria.

The latest person to test negative is the missionary, who had arrived from Liberia several days ago, and was suffering from a fever. He was transferred via ambulance from one of his order’s residencies in the Madrid suburb of Pozuelo.

The woman who was one of the seven people to be transported in the same ambulance as Ebola victim Teresa Romero broke out in a fever on Thursday morning, explained Fernando Simón, the spokesperson for the scientific committee created by the government to manage the Ebola crisis. She was isolated in her home until she could be transferred to Carlos III on Thursday afternoon. The first test for the virus in her blood has come back negative.

Simón had previously said that, of the people who came into contact with Romero while she was contagious, the ambulance passenger was one of those with the lowest risk of infection. The ambulance was not decontaminated until 12 hours after it had transferred the nursing assistant to the Alcorcón emergency room. In total, seven patients were transported in the vehicle before it was properly disinfected.

The latest person to test negative is the missionary, who had arrived from Liberia several days ago

Spain had been forced to activate health protocols at the Adolfo Suárez Madrid-Barajas Airport on Thursday after a passenger on an Air France flight from Paris complained of fever and trembling. The man, who was completing a journey from Lagos, Nigeria, was taken to Carlos III in the afternoon. He tested positive for malaria and negative for Ebola.

The missionary arrived in Madrid from Monrovia, Liberia, last Saturday. He belongs to the same order – San Juan de Dios – as Spanish priests Miguel Pajares and Manuel García Viejo, who contracted Ebola while treating infected patients in west Africa. The pair were later repatriated by the Spanish government and died while in care at Carlos III Hospital. Teresa Romero was on the team that took care of the missionaries.

According to his order, the third priest is said to be elderly, and had been considered a low-risk patient because he had not been in contact with Ebola patients, Pilar Álvarez reports.

The Red Cross nurse and a Nigerian plane passenger have been found to be suffering from malaria

The Canary Islands government also activated health protocols to deal with a possible case of Ebola infection in La Candelaria Hospital, in Tenerife. The person in question arrived from Sierra Leone eight days ago and has a fever of 37.7ºC, Txema Santana reports. The man arrived in Brussels on October 8 and in Tenerife on October 12. Two people who live with him have also been isolated, but are not showing any Ebola-related symptoms, Canarian health authorities said in a press conference.

EL PAÍS has learned that the man is a Red Cross nurse who spent a month in a hospital run by the organization in Kenema. The Red Cross set up a hospital there to treat Ebola patients at the beginning of August.