A teenager part of one of the largest indigenous tribes in the Amazon has died after testing positive for COVID-19, according to Brazilian health officials. There are fears the coronavirus, which has already devastated much of the world, could wipe out remote indigenous tribes in South America.

Alvanei Xirizana, 15, died on Thursday in a hospital in the state of Roraima, Reuters reported, citing local health authorities. He belonged to the relatively isolated Yanomami tribe, whose more than 38,000 members occupy rainforests and mountains in northern Brazil and southern Venezuela, according to human rights group Survival International. Advocates say deforestation and development by miners and loggers, encouraged by Brazilian President Jair Bolsonaro's policies, have threatened indigenous people's territory.

So far, two other indigenous people — an 87-year-old woman from Para and a man from Manaus — have died from coronavirus. Brazil has had more than 19,600 confirmed cases and over 1,000 deaths from COVID-19.

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Paula Vargas, the Brazil program manager at Amazon Watch, an organization focused on protecting the Amazon and advancing the rights of indigenous people, told CBS News that COVID-19 is a "huge threat" to the over 850,000 indigenous people in Brazil.

"If we are able to close our homes and shut off our offices and be safe at home from the virus, those communities are not having the same safety because the government and the authorities are not able to take from their territories the invaders," she said Friday. "The miners and illegal loggers — they don't do home office, so they're in their territories."

She added some indigenous organizations have reached out to Amazon Watch about groups of missionaries that are trying to reach them, even though they're in isolation.

"While all the world is telling people to stay at home, those indigenous people are suffering from people trying to invade their forest," she said. "And if that happens, we already know that boy... he's from the Yanomami people. Miners are all over the place. They have people who are in contact with them."

"We are seeing the possibility of genocide happening," Vargas said.

Amid the worldwide pandemic, many indigenous peoples quickly organized to self-isolate, cancel big events, and translate health guides into native tongues, according to Vargas. However, hunger during the quarantine also poses problem, forcing indigenous people to ask for donations of food and clean water.

"Many of them sell their products," she said. "If they're not able to go to the cities, there's a big crisis."

Bolsonaro, who took office at the beginning of 2019, has pushed for development over the conservation of the rainforest. Experts have linked the staggering number of fires in the Amazon last year to the rush to exploit the resources in the rainforest.

Vargas stressed that it's in the whole planet's best interest to keep indigenous peoples safe.

"We also understand on a global level that they are the guardians of the forest that keep our planet healthy," she said. "We don't want climate change. If they disappear from their land, we know the level of deforestation has gotten worse."