Health authorities in Brazil are monitoring two patients for possible Ebola infection in the country's two biggest cities, São Paulo and Rio de Janeiro.
A man, 37, from the Democratic Republic of the Congo (DR Congo) "exhibited symptoms such as fever", São Paulo's state government said.
In Rio state, the health department said it had activated safety protocols after a Belgian man who arrived from Uganda showed "viral symptoms such as cough, chills and diarrhoea".
The test results for both patients should become available next week.
If confirmed, they would be the first infection cases outside Africa since the outbreak began in DR Congo.
There are now more than 1,000 suspected Ebola cases in DR Congo, with at least 246 deaths. Uganda has reported nine confirmed cases and one death.
The current outbreak has been caused by a rare strain of Ebola known as Bundibugyo, which has no proven vaccine and kills about a third of those infected.
While the two patients in Brazil are still being monitored for Ebola, they have already both been diagnosed with other conditions: in São Paulo, the man from DR Congo tested positive for meningitis, while in Rio, the Belgian patient tested positive for malaria.
Ebola viruses normally infect animals, typically fruit bats, but outbreaks among humans can sometimes start when people eat or handle infected animals.
Ebola spreads through direct contact with the bodily fluids of an infected person, including sweat, saliva, blood, semen, excrement, urine and vomit.
