Friends and family gathered around the limp body of a 15-year-old boy laid out on a bed in a thatched hut near the Brazilian town of Iguatemi, close to the border with Paraguay. A shaman shook a small wooden rattle while chanting and dancing — final rites for yet another victim of a suicide epidemic that has plagued the Guaraní Indians of the western Brazilian state of Mato Grosso do Sul.

The boy, Dedson Garcete, had hanged himself — one of 36 suicides among tribe members in 2014 through September, and one of about 500 among the tribe of 45,000 since 2004, according to Zelik Trajber, a pediatrician with the special secretariat for indigenous health within the Ministry of Health in Mato Grosso do Sul.

Indigenous peoples suffer the greatest suicide risk among cultural or ethnic groups worldwide. Australian Aboriginal and Torres Strait Islander men ages 25 to 29 have a suicide rate four times higher than the general population in that same age group in Australia, according to the country’s Department of Health.

In the United States, suicide is the second leading cause of death, behind accidents, for American Indian and Alaska Native men ages 15 to 34, and is two and a half times higher than the national average for that age group, the Centers for Disease Control and Prevention reports.

Among the indigenous in Brazil, the suicide rate was six times higher than the national average in 2013, according to a study released in October by Brazil’s Ministry of Health. That translates into 30 suicides per 100,000 people. Among members of the Guaraní tribe, Brazil’s largest, the rate is estimated at more than twice as high as the indigenous rate over all, the study said.