It was a quiet day at an otherwise bustling St Thomas School in Dhurwa, Ranchi. A limp black flag at the main gate said more than words ever can. It said how the campus would sorely miss one of its cherubs - fourth grader Ananya who died a sudden and unexplained death in school a day ago. Without her, there were no classes on Wednesday.

Barely 4km away, the parallel quietness was depressing at the nine-year-old's Birsa Chowk home. Mother Tripti, who underwent a surgery recently, and father Ajay Agarwal, a flourmill owner who doted on his only daughter, had had to be sedated to buffer their shock.

Little Anshuman, Ananya's younger brother and a Class II student of Sarla Birla School, was the only proof of life. At seven, he was unable to fathom his loss as yet and played on with other kids. But at times, when he perhaps missed his didi, Anshuman sneaked onto his grandpa's lap for solace.

Sachidanand Agarwal, Ananya's and Anshuman's dadda (an endearment for grandfather), seemed the only one with nerves of steel. The elderly man could not stop touching his own cheeks in reminiscence of the final good morning kisses his beloved granddaughter had showered on him before leaving for school on Tuesday. "What took her life? She was a chirpy little girl," he kept thinking aloud, staring blankly here and there.

Ananya had reached campus at 7.15am and was found dead near the toilet 15 minutes later. While there has been no clear medical explanation to what caused her untimely demise, Sachidanand conceded that she was a weak child.

"She had not been healthy since birth. Two years ago, she began complaining of abdominal and chest pains. Tests done in Ranchi failed to diagnose what was ailing her. We took her to AIIMS in Delhi. Doctors there named a disease, which I can't remember. They said it was not curable, but a healthy lifestyle and strict food regimen could help her. We never allowed her to eat junk food, not even ice cream," the sexagenarian's voice choked.

"The school had rushed her to hospital, but it was fate. She will never wake me up again," he said and walked away perhaps to hide his tears.

At HEC Plant Hospital, where Ananya was taken from school, both the doctor who declared her brought dead and chief medical officer K.K. Kadam refused to speak to The Telegraph on her medical history.

However, another doctor of the same hospital shared his speculation. "It seems she had been suffering from mesenteric lymphadenitis or inflammation of lymph nodes that line the abdominal wall. It is common in children. But, it is just a guess based on what her relatives (Sachidanand) said," the doctor observed.

Dr Arun Kumar Sharma, the head of paediatrics at RIMS, said mesenteric lymphadenitis was not a rare condition, but conceded that diagnosis was difficult because of the position of the lymph nodes. On whether it could cause sudden death, he said, "No. It usually causes severe symptomatic pain in the abdomen giving scope for medical intervention."

Was Ananya in pain when she rushed downstairs from her classroom? No one knows. Everyone just remembers her smiling adieu.