Officials in India have been left baffled by an illness that has left more than 500 people hospitalised and one dead.
The mystery illness has struck in the southern state of Andhra Pradesh, and was first detected on Saturday evening in Eluru.
Symptoms ranging from nausea, anxiety, loss of consciousness and convulsions have been reported in at least 546 patients who have been admitted to hospital.
Many have recovered and returned home, while nearly 150 are still being treated, according to a government spokesperson.
All those who have fallen sick have tested negative for COVID-19.
Teams of experts have arrived at the city from India's top scientific institutes to try to work out what is happening.
One thing baffling experts is the lack of a common link among those who have fallen sick, who aren’t related to each other, don’t live in the same areas, and are from different age groups.
A government statement said those who had fallen ill reportedly “suffered from dizziness, fainting spells, headache and vomiting”.
A 45-year-old man was hospitalised with symptoms resembling epilepsy and died on Sunday evening, doctors said.
Geeta Prasadini, the director of public health, said his autopsy didn’t shed any light on the cause of death.
The hypothesis currently being tested is that people ate vegetables tainted with pesticides made of organic compounds containing phosphorus. But this is an “assumption” based on the fact that such pesticides are commonly used in the area and not on any evidence, Prasadini said.
She said that experts were testing to see if pesticides had contaminated fish ponds or spilled over to vegetables.