A mysterious sickness has killed nearly 100 children in India

Nearly 100 children have died this month in India from an illness that impairs the functioning of the brain and sends the level of glucose in the blood plummeting. 

The deaths have occurred in and around the city of Muzaffarpur in the northern state of Bihar, one of the poorest regions in India.

The illness strikes the area each summer, but in recent years, the death toll has been less than 20.

This year, at least 97 children have died, most of them under the age of 7, said Alok Ranjan Ghosh, a senior government official in Muzaffarpur.

 About 100 more remain in hospitals. The deaths represent the worst toll since 2014, according to figures provided by a state health official.

Doctors describe the illness as acute encephalitis syndrome, or AES, which is characterized by the rapid onset of fever combined with disorientation and seizures. 

officials say the precise cause of the outbreak remains unclear.

The illness has been observed in the area since 1995, Kumar said, flaring up during the Indian summer when temperatures soar and subsiding with the arrival of the rains and somewhat cooler weather. Children are arriving at hospitals with critically low blood-sugar levels.