A 37-year-old man from the Democratic Republic of the Congo (DRC), where the outbreak has been concentrated, “exhibited symptoms such as fever, meeting the definition of a suspected case” of Ebola, the Sao Paulo state government said in a statement on Saturday.

While initial tests did not detect the Ebola virus in the patient, he is being monitored and isolated as a precautionary measure at a specialised infectious disease facility, the statement said.

The health department in Rio de Janeiro state, meanwhile, reported that it had activated safety protocols after a man from Uganda showed “viral symptoms such as cough, chills, and diarrhoea”.

The Rio city government said in an email to AFP that the patient tested positive for malaria Saturday evening and “the case remains under investigation”.

There have been more than 1,000 suspected cases of Ebola in the DRC since the outbreak was declared on May 15, including nearly 250 deaths, the Africa Centres for Disease Control and Prevention said on Thursday.

Several infections and one death have been confirmed in neighbouring Uganda.

However, the true reach of the outbreak in the DRC, which is thought to have been circulating before it was detected, is likely to be much wider, the World Health Organization has warned.

The Sao Paulo government said that despite the suspected case, “the technical assessment indicates that the risk of the disease being introduced into Brazil and South America remains very low.”