A mystery disease has killed dozens of Warao Indians in recent months in a remote area of northeastern Venezuela, according to indigenous leaders and researchers from the University of California at Berkeley, who informed health officials here of the outbreak on Wednesday.

At least 38 people have died, including 16 since the start of June, said Charles Briggs, an anthropologist at Berkeley, and Dr. Clara Mantini-Briggs, a medical researcher there. They are a husband-and-wife team known for their research on a cholera outbreak that killed 500 people in Venezuela in the early 1990s.

Preliminary studies of the latest outbreak indicate that it may be a type of infectious rabies transmitted by bites from bats, the researchers said. The symptoms, which last three to six weeks, include partial paralysis, convulsions and an extreme fear of water, they said, and those who die become rigid just before death. The disease is believed to be fatal in most cases.

"The authorities must investigate this outbreak with extreme urgency," said Dr. Mantini-Briggs, a Venezuelan public health expert who has advised President Hugo Chávez's government on policies to combat dengue fever. "Fear about the disease has intensified among the Warao while a preventative response is needed now."

The disease is found in the swampy Delta Amacuro, near the border with Guyana. The state is inhabited largely by Warao Indians, a nomadic indigenous group said to number more than 20,000.

Recently, many animals in the area have died, the researchers said, but no correlation has been established between those deaths and the disease.

Warao leaders, accompanied by the researchers, took photos and written testimonies documenting the disease to the Health Ministry here on Wednesday for a meeting with government epidemiologists. But they were kept waiting for several hours.

"We traveled by bus 16 hours to Caracas to make the authorities aware of the situation with the hope of getting some response," said Norvelis Gómez, a Warao paramedic who was one of four community leaders in the group. "And we are met with disrespect on every level, as if the deaths of indigenous people are not even worth noting."

Framing their concerns within the polarizing world of Venezuelan politics, in which criticism of the government is often considered tantamount to betrayal, the Warao leaders and the Berkeley researchers emphasized that they all supported Mr. Chávez's policies and that their intent was not to smear his government.

"All we request is for authorities to respond to this disease as they would if it occurred in a rich district of Caracas," said Enrique Moraleda, a Warao leader in Mr. Chávez's United Socialist Party who was part of the group.

The group was allowed to meet with the government epidemiologists on Wednesday evening, and members said officials promised them that the disease would be investigated as soon as possible.