Komirepalle: The men gathered on a recent evening as the sun slipped lower in the sky, turning the rice fields golden. There was disturbing news: Yet another person from the village had fallen mysteriously ill the night before.

The sickness was always the same, the farmworkers said. Burugu Ravi was transplanting rice seedlings last month when he collapsed and had a seizure, he said. K.I. Yarlapati David Raju crumbled just steps from the bench where he was now sitting. Prasad Kali said his 26-year-old son had suffered three seizures, biting his tongue badly each time. Gurram Nageswara Rao said his wife suddenly started jerking and frothing at the mouth; a few days later his 11-year-old grandson had a seizure after eating dinner.

“It can happen at any moment, when walking, when sleeping,” Rao said. “We don’t know when people will suffer.”

Rao’s village is part of an unusual medical whodunit. Since December, more than 650 people in an agricultural region near India’s southeastern coast have fallen sick in an episode that has perplexed doctors and scientists alike. The experts agree on two things: It is not a contagious illness, and the most likely cause is a toxin. But that is where the consensus ends.

At a time when India is battling one of the world’s largest coronavirus outbreaks, the mysterious poisoning of hundreds of people has barely registered beyond the region. Health officials point out that victims tend to recover quickly, with few lasting ill effects.

Yet the incident is part of a broader debate over environmental hazards in India and the adequacy of government safeguards. The investigation into the mystery illness, for instance, revealed that people in the region were facing an array of longer-term health risks, even as the exact cause of the seizures remains elusive.

B. Chandrasekhar Reddy, a senior neurologist who was a member of the expert panel set up to investigate the episode, said there are clues about the source of the syndrome, but not proof. “So far it is a mystery only,” he said.

In December, he traveled to Eluru, the small city in the state of Andhra Pradesh where the incident began. At the main hospital he witnessed multiple people losing consciousness or falling down with convulsions. He had never seen anything like it, he said. A review of the medical literature yielded no parallels.

A.V.R. Mohan, the superintendent of the hospital, said he initially feared a new virus — “because it was covid time” — but tests for viral or bacterial infections came back negative. The victims had various injuries sustained during the seizures, including while driving. One man died at the Eluru hospital hours after having a seizure, although the precise cause of the death remains unclear, Mohan said. Three people in two villages affected by the illness also drowned after suddenly collapsing, but doctors said there is no evidence linking the deaths to seizures.

A city of more than 200,000, Eluru is surrounded by agriculture. Tractors hauling open trailers sometimes ply the streets together with streams of cars and motorcycles. Vendors sell bright-green guavas, giant watermelons and towers of bananas.

P. Nagajyothi, a 28-year-old mother of two, has lived in the city her whole life. One morning in early December, she rose before dawn to bathe ahead of a religious festival. She was standing in the small outdoor area the family uses to wash when she lost consciousness. She managed to get up — her thoughts were of the cleaning and cooking she had to do that day — only to pass out again. When she awoke, she had been shifted inside to a bed. She had bitten her tongue so hard she had trouble eating for a week.

Nagajyothi had no idea what made her sick. The water from the municipal pipes sometimes has a strange smell and a brownish color, she said, but she doubted it was the cause. “If it were a water problem, then everybody would be sick, no?” she said.

In the days after her episode, about five more people on her modest street experienced similar symptoms. A community health worker did a survey of three neighborhoods including Nagajyothi’s and found 36 cases in total, all remarkably alike: dizziness, loss of consciousness, seizures, frothing at the mouth. The overall tally in the city would eventually skyrocket to more than 600. In January, residents of Komirepalle and Pulla, two villages to the northeast of the city, began experiencing the same syndrome.

K. Bhavani, 25, arrived in Pulla with her 3-year-old son Harsha earlier this month to visit relatives. As her aunt was boiling milk in the morning for Harsha to drink, the toddler went rigid and began shaking and foaming at the mouth.

The local clinic referred them to the larger hospital in Eluru, where they arrived several hours later. As they checked in, Bhavani dropped to the ground and began convulsing. The next thing she recalls is being administered saline through an intravenous drip and wondering why they were treating her. Two hours later, she had a second seizure.

Bhavani was still feeling weak as she prepared to leave the hospital on a recent afternoon. “I’ve never had health problems, nothing,” she said as her aunt sat next to her on a heavy iron bed.

In the early days of the outbreak, it seemed that everything was a possible cause. As worries mounted, so too did the potential explanations — poor sanitation, leaching pipes, chemicals in the water, pesticides in food, contamination by heavy metals, even mosquito eradication efforts.

Experts from more than a dozen different organizations — including teaching hospitals, national scientific institutes and the World Health Organization — rushed to the city. They took samples of blood, spinal fluid, urine, water, milk, grass, rice, fish, tomatoes, eggplants, even the air.

A 21-member expert committee examined the results and submitted their findings on what they called the “Sudden Convulsions of Unknown Origin” in Eluru. In the battery of tests, they uncovered things they weren’t looking for, including undiagnosed cases of dengue fever and chikungunya, two mosquito-borne illnesses, as well as a few suspected coronavirus cases. Many of the tests turned up nothing unusual at all.

Others uncovered more worrisome things. Several of the blood samples showed high levels of heavy metals such as lead and nickel. Elevated levels of mercury were detected in rice. Mercury was also found in surface water and groundwater — at up to 26 times above the permissible limit in the latter, the expert committee report said.

While the presence of such metals points to longer-term health risks — including damage to the brain and kidneys — they were unlikely to cause the seizure syndrome, doctors told the committee, especially since victims tended to recover quickly.

The focus turned to pesticides. Tests by India’s National Institute of Nutrition in Hyderabad found herbicide present in tomatoes and eggplants. They also found triazophos — an organophosphate pesticide — in household water samples (although not in water from pumps or reservoirs).

But several doctors, including Mohan of Eluru hospital, said the symptoms did not match that type of pesticide poisoning. Instead, they believed it was a case of organochlorine pesticide poisoning, a group that includes chemicals such as DDT.

While experts say the syndrome may be a case of pesticide poisoning, “there is no unanimity” on which type, said Bhaskar Katamneni, health commissioner for the state of Andhra Pradesh. The area around Eluru is known to use large amounts of pesticides, he said, and perhaps they seeped into the water supply. But how and when that might have happened is still unclear.

In Komirepalle, a village of about 200 households down a rutted ocher road with a national highway visible in the distance, the residents still have no answers about what happened to them or how they might protect themselves.

Raju, one of the farm workers gathered in Komirepalle on a recent evening, is a tall, slender man with hollow cheeks. At the start of March, he was standing in the shadow of a shrine when friends heard him make a noise — a kind of groan — and then go rigid and fall. He still feels dizzy in the mornings and no longer works in the fields regularly.

“I’m afraid,” he said. “How can I know why this happened?”

(from the Washington Post)