Traces of heavy metals such as lead and nickel have been found in samples taken from 550 people stricken by a mystery illness in a southern Indian town where some victims have collapsed in the street, officials have said.
Indian authorities have found traces of lead and nickel particles in blood samples, after hundreds of people were hospitalised due to an unknown illness in the southern state of Andhra Pradesh.
Teams of doctors, including those from New Delhi's premier All-India Institute of Medical Sciences (AIIMS), are investigating the death of one person and hospitalisation of more than 400 in the past few days.
Andhra Pradesh's state government said the AIIMS team had found traces of lead and nickel in their samples, while a second hospital is also running similar tests.
The illness has infected more than 300 children, with most of them suffering from dizziness, fainting spells, headaches and vomiting. They have tested negative for Covid-19.
High levels of lead in the bloodstream can impair development of brains, nervous systems and vital organs such as heart and lungs.
Earlier on Tuesday, federal lawmaker GVL Narasimha Rao, who is from the state, said on Twitter that he had spoken with government medical experts and that the "most likely cause is poisonous organochlorine substances."
“It is one of the possibilities,” said Geeta Prasadini, a public health director in Andhra Pradesh state, adding they were awaiting test reports to ascertain the cause.
Organochlorines are banned or restricted in many countries after research linked them to cancer and other potential health risks. However, some of the pollutants remain in the environment for years and build up in animal and human body fat.
It was not immediately clear how extensively the chemicals are used in India, though it is found in DDT applied for mosquito control.
Exposure to organochlorine pesticides over a short period may produce convulsions, headache, dizziness, nausea, vomiting, tremors, confusion, muscle weakness, slurred speech, salivation and sweating, US health authorities say.
Hundreds of people have been treated for a mystery illness in a southern Indian town, with one doctor ruling out "mass hysteria" at a time nerves are already frayed because of the coronavirus.
The government rushed medical experts to Eluru in Andhra Pradesh state to investigate the illness, which first appeared on Saturday causing seizures, nausea and chronic pain. People started convulsing without any warning, said Prasadini, the director of public health.
Officials said 546 patients were admitted to hospitals. Many have recovered and returned home while 148 are still being treated, said Dasari Nagarjuna, a government spokesperson, but the death of a 45-year-old man at the weekend was attributed to the mystery disease.
Some officials pinpointed a possible role of chemical additives in pesticides, while residents have highlighted a problem with garbage and feral pigs.
“But nobody knows," Prasadini admitted.
"Some people are saying that it is mass hysteria but it is not," said AS Ram, a senior doctor at Eluru government hospital.
He said most victims had suffered genuine symptoms, but "we are unable to diagnose what is causing it."
The government has sent doctors from the National Institute of Virology, National Centre for Disease Control and the All India Institute of Medical Sciences to investigate.
The team was collecting samples of edible oil, rice, blood and urine for analysis.
"Most of the patients are coming in with minor head injuries or a black eye as they collapsed suddenly with the seizure," Ram said.
"But within one or two hours most of them are fine."
Any link to Covid-19?
Police constable Kiran Kumar, who collapsed while on duty Monday said he had been left "scared" after being semi-conscious for more than two hours.
"My colleagues told me, I shouted something and collapsed. I injured my right shoulder due to falling on the road."
According to district officials, the illness is not spread person-to-person.
They released a report on Monday which said symptoms included "epilepsy for 3-5 minutes, forgetfulness, anxiety, vomiting, headache and back pain."
What is confounding experts is that there doesn't seem to be any common link among the hundreds of people who have fallen sick. All of the patients have tested negative for Covid-19 and other viral diseases such as dengue, chikungunya or herpes.
They aren't related to each other. They don't all live in the same area. They're from different age groups, including about 70 children, but very few are elderly.
Opposition leader N Chandrababu Naidu demanded on Twitter an “impartial, full-fledged inquiry into the incident.”
India is already in the grip of coronavirus with the world's second-highest number of cases, and soon expected to pass 10 million.
And Andhra Pradesh state is among those worst hit by Covid-19, crossing over 800,000 detected cases.
The health system in the state, like the rest of India, has been ravaged by the virus.