The coronavirus has spread rapidly through the Yanomami indigenous reservation in northern Brazil and more than a third of its 27,000 people could have been exposed, according to a report produced by their leaders.

The Yanomami’s territory, which is also home to 600 Ye’kwana people, is the largest indigenous reservation in Brazil. It is threatened by swarms of illegal gold miners who have invaded their lands bordering Venezuela and are thought to be a major contagion risk.

Confirmed cases of COVID-19 in the reservation have risen some 260% between August and October, said the report, released on Thursday by the Yanomami and Ye’kwana Leadership Forum.

So far, there have been 1,202 confirmed cases and 23 deaths, the report said.

The data was gathered from the indigenous health service and a survey by radio communication with the 366 villages, some of them still very isolated, across the 96,650 square kilometers (37,320 square miles) of reservation.

The report accused the government of failing to protect the Yanomami people from the pandemic. It said only 4.7% of the reservation’s population had been tested for COVID-19 and 70% of those tested were positive, but no tests had been done in one third of the villages.

“Every day more and more Yanomami are being exposed to infection by the virus,” Dario Kopenawa, vice president of the Hutukara Yanomami Association and son of its main shaman Davi Kopenawa, told Reuters by telephone.

“There are health professionals working here, but too few and they have no equipment. The federal government does not provide enough support,” he said.

In July, a military mission visited a remote part of the reservation in helicopters, bringing protective equipment and medical supplies.

But its arrival with a group of journalists annoyed Yanomami leaders who saw it as an unannounced media show that undermined the tribe’s efforts to remain isolated from contagion.

The government’s indigenous health service Sesai did not respond to a request for comment.