Eluru (Andhra Pradesh): Chief Minister Y.S. Jagan Mohan Reddy on Tuesday asked officials for a detailed report on the mystery illness.
Earlier high levels of nickel and lead have been found in the blood samples of victims.
"The public health personnel and other departmental staff should also probe the issue deeply and find out the reasons for the illness," said Reddy as he reviewed the situation after a visit on Monday.
Eluru, 58 km northeast of Vijayawada, and the headquarters of West Godavari district, is a aquaculture hub.
Meanwhile, West Godavari Joint Collector Himanshu Shukla says a team from All India Institute of Medical Sciences (AIIMS) has already arrived to investigate the disease.
However, he refuted media reports claiming that AIIMS has established the primary reason for the mysterious illness as heavy metals in drinking water and milk.
"AIIMS has not given this report," Shukla told IANS. He confirmed that excess amounts of lead and nickel were found in the blood samples of the victims, but ruled out their presence in water and milk.
Shukla said that AIIMS are still continuing with their investigations, and may find the actual cause by Wednesday.
Meanwhile, the total cases rose to 564 by 10 p.m. on Tuesday, out of which 462 have been discharged while 71 are bed-ridden and 30 referred to other hospitals.
Majority of the cases (310) occurred in the age bracket of 12 to 35 years, followed by 180 cases among those above 35 years.
IANS report with edits