Health authorities said Thursday they have identified a third death in Brazil linked to the Zika virus, but it is not clear if the disease was the sole cause.
The latest case "was communicated to the World Health Organization [WHO] and we are studying it in more depth because we have just received the information," Health Minister Marcelo Castro said during a news conference.
The victim, a 20-year-old woman, died last April, the ministry said.
Claudio Maierovitch, director of the ministry's communicable disease surveillance department, cautioned against drawing conclusions.
"It's not possible at this point to say that Zika was the sole cause of death," he said.
Pedro Vasconcelos, a doctor at the Evandro Chagas Institute, which is analyzing samples from the victim, said the woman had "very unusual respiratory symptoms" for Zika.
"It's possible she had pneumonia that was aggravated by Zika and she eventually died," he said.
Brazil last year announced that an adult and a teenager infected by Zika were known to have died.
The virus is transmitted by the Aedes aegypti mosquito and causes only mild symptoms in most people.
However, Zika has been linked to a rapid rise in the number of children born with microcephaly—abnormally small heads and brains—to mothers infected during pregnancy.
There is currently no cure or vaccine for Zika.
Brazil has been most affected by the outbreak, with 1.5 million people infected since early 2015.
The country has confirmed 404 cases of Zika-linked microcephaly and 3,670 others are under study.
The WHO has declared the rise in Zika-linked birth defects an international emergency.
Confirmed cases have been found in 26 countries, spanning 7,000 kilometers (4,400 miles) from Mexico to Paraguay, according to the Pan-American Health Organization.
President Barack Obama on Monday asked for more than $1.8 billion in emergency funds to tackle the fast-spreading virus in the United States and beyond.
The second most-affected country, Colombia, last week announced three deaths of Zika-infected patients who had also contracted Guillain-Barre syndrome—a neurological disease that can cause paralysis in humans.
Colombia has reported more than 22,600 confirmed Zika cases.
However, the WHO has urged caution over linking the virus to Guillain-Barre syndrome.
Individual countries and regions are beginning to mobilize to limit the spread of Zika and are cooperating on developing a vaccine.
Castro, the Brazilian health minister, said 15 American experts arrived in the country to study Zika this week.
"The vaccine is not a Brazilian concern, but global," he said. "We could have a pandemic in the Americas with four million people infected by the Zika virus."
Despite fears about Zika in Brazil, experts say the Aedes aegypti mosquito also transmits dengue, which is endemic in the country and even more dangerous.
Some 863 people died from dengue in Brazil last year, up 82.4 percent from the year before, the government says.
Explore further: WHO cautions against linking Zika virus with rare nerve disorder