Traces of lead and nickel were found in the blood samples of people who contracted a ‘mystery’ illness in the South Indian state of Andhra Pradesh.
One person died while at least 550 people in the city of Eluru complained of convulsions, nausea and fainting.
Doctors have been trying to diagnose the illness, which struck parts of the town last week amid the Covid outbreak.
The state of Andhra Pradesh has been one of the worst-affected states – at more than 800,000, it has the country’s third-highest case count.
A statement from the Chief Minister’s Office said preliminary findings indicated the presence of lead and nickel in blood which could have caused the symptoms. It added that more tests needed to be conducted.
Experts pointed out that the disease does not seem to spread from person to person.
Chief Minister Jaganmohan Reddy visited the Eluru Government Hospital and met patients undergoing treatment.
Experts from the World Health Organisation (WHO) are also expected to arrive in Eluru for further investigations, medical officials have told local media.
The opposition Telugu Desam Party has demanded an inquiry into the incident, insisting that contamination was the cause of the mystery illness.