Health authorities have confirmed that at least 109 children have died in the city of Muzaffarpur due to inflammation or infection in the brain. The fatal diagnosis is acute encephalitis, a neurological disease caused by either a virus or environmental toxins connected to the lychee fruit.
Protestors were yelling for government officials, who have been trickling in to assess the situation, to leave the hospital premises.
Local media showed mothers sobbing, parents running alongside gurneys transporting their babies, and droves of parents entering the hospital premises with children in their arms, asking for help.
Official responses -- both medical and administrative -- have been weak and delayed, some politicians say. In just two hospitals in the region, more than 400 children complaining of fever, dizziness and delirium have been admitted since the start of the year.
Acute encephalitis syndrome has spread across a few districts in India, focused in pockets in the poorer states of Uttar Pradesh, Bihar and West Bengal, which also have some of the country's hottest summers.
In 2014, nearly 117 deaths were reported in Muzaffarpur. But the death toll had dipped over the past few years.
"This year, the number [of cases] has gone up a bit," said Sanjay Kumar, a senior state health official. "The heat wave has been too intense, and it has gone on for too long."
What causes acute encephalitis?
Indian health officials and experts have been unable to accurately point to the cause of certain types of acute encephalitis syndrome and whether, as in the case of the latest India outbreak, it is viral or caused by the consumption of a toxin.
Vietnam and Malaysia have also had outbreaks, according to a study
published in 2012. Both countries have tried for years to contain the spread or eliminate the cause of the condition. Experts have tried to narrow it to a virus, certain mosquito species and finally the lychee fruit.
Research papers and local officials point to the presence of lychee as a factor that may have significance in understanding the cause behind the outbreak. The fruit is widely grown in and around Muzaffarpur.
"The association between litchis (or lychees) and acute encephalitis remains unclear. As with other emerging viruses, we face a multifactorial problem that seems to have litchi (or lychee) fruit production and harvest as its focal point," the paper says.
Children may be at a higher risk of getting infected because of lower immunity, said Dr. Neelu Desai, a pediatric neurologist in Mumbai. "If it is virus or a toxin in something they are eating, we don't really know," she added.
"Between 2008 and 2014, there have been more than 44,000 cases and nearly 6000 deaths from encephalitis in India, particularly in Uttar Pradesh and Bihar," according to a research paper
published in the Indian Journal of Medical Research in 2017.
The Indian Ministry of Health has deployed a "high-level disciplinary team to Muzaffarpur to support the state in epidemiology research," according to a news release, and has announced the establishment of a research center there.
"To establish the cause of the disease, there is urgent need for an interdisciplinary, high-quality research team. The research team shall work with the children suffering from [acute encephalitis or Japanese encephalitis], looking at various aspects including periodicity, cycle of disease, environmental factors and meteorological data, besides other factors," said Harsh Vardhan, India's minister of health and family welfare.
Bihar state officials have issued warnings for the past few years across the Muzaffarpur district, advising parents to ensure that children stay hydrated and do not go to sleep on an empty stomach.
Kumar said that the affected children "are from poor families, and they do not have sugar reserves, and they are also malnourished."
Bihar health authorities have confirmed that all children displayed signs of hypoglycemia -- low blood sugar -- before they died.
"The liver stores glycogen. When the sugar level goes down, the liver releases extra sugar to balance it out, but if there is no extra sugar and there are only toxins, then they get released," Kumar said.
Officials have blamed the severe heat wave, which has lasted for more than 30 consecutive days, as the reason behind the rise in cases but aren't sure how heat plays a role in the spread of acute encephalitis syndrome.
Due to intense heat, the Bihar state government has ordered all government and private schools in the state to be shut until Monday.