There are about 26,000 Yanomami in the Amazon rain forest, in Venezuela and Brazil, where they subsist as seminomadic hunters and cultivators of crops like manioc and bananas.

They remain susceptible to ailments for which they have weak defenses, including respiratory diseases and drug-resistant strains of malaria. In Puerto Ayacucho, they can be seen wandering through the traffic-clogged streets, clad in the modern uniform of T-shirts and baggy pants, toting cellphones.

Earlier this decade, the anthropology world was consumed by claims by the writer Patrick Tierney that American scholars may have started and exacerbated a measles epidemic in the late 1960s that killed hundreds of Yanomami.

And claims of medical neglect emerged before Mr. Chávez expelled the American missionaries, who numbered about 200. They administered care to the Yanomami with donated medicine from the United States and transported them to clinics on small propeller planes using dozens of airstrips carved out of the jungle.

New Tribes, the most prominent of the expelled groups, has denied Mr. Chávez’s charges of espionage but declined to comment for this article, citing the tense relations between Venezuela and the United States.

Mr. González and other Yanomami leaders provided the names of 50 people, including 22 children, who they said died from ailments like malaria and pneumonia after the military limited civilian and missionary flights to their villages in 2005. The military replaced the missionaries’ operations with its own fleet of small planes and helicopters, but critics say the missions were infrequent or unresponsive.

Image Some Yanomami consider the ubiquitous images of them in Puerto Ayacucho patronizing. Credit... Scott Dalton for The New York Times

The Yanomami leaders said they made the list public after showing it to health and military officials and receiving a cold response. “They told us we should be grateful for the help we’re already being given,” said Eduardo Mejía, 24, a Yanomami leader from the village of El Cejal.