Researchers are scrambling to discover what is blinding children in the Amazon city of Araguatins in the remote northern Brazilian state of Tocantins, health officials said on Wednesday.

Three of the 365 children identified by the Disease Control Agency of Tocantins with similar lesions on their eyes are totally blind. Two others were blinded in one eye and have undergone surgery.

The agency reported the first 17 cases in November 2005.

Since then, state and federal health officials, epidemiologists from the University of Sao Paulo and the Osvaldo Cruz Foundation in Rio de Janeiro and specialists from Rio Grande do Sul and the Center for Disease Control in Atlanta have been compiling data to identify the cause of the disease.

“At this point we are ruling out nothing,” the coordinator for Disease Control in Tocantins, Perciliana Bezerra, told Reuters.

“We can say that it is only affecting children in Araguatins and not in the surrounding areas and there appears to be a link with something in the Araguaia River.”

Health officials have issued advisories banning swimming or bathing in the river around the city.

Bezerra said one likely possibility was a local snail that may be transmitting a fungus, bacteria, virus or parasite but local vegetation or animals that live near or in the river may also be the host or cause of the disease.

Health ministry officials are expected to call a meeting of the specialists involved in the research to try to reach a consensus on the mystery disease in early March, Bezerra said.