Why does the adenovirus affect children harmfully?

Two of the three casualties of the last 24 hours were infants and died at Dr BC Roy Post Graduate Institute of Paediatric Sciences in Phoolbagan. The third, a one-and-a-half-year-old toddler, died at Medical College Hospital.
The viral panel test results of two of the unconfirmed - but suspected adenovirus - casualties is awaited. Doctors would not confirm whether those were also due to adenovirus without the final results. The results of a viral panel test, which confirms the virus responsible for infection, are supposed to arrive in "not more than five hours, from sample collection to delivery", according to an expert. One of the two boys, whose infections are as yet unconfirmed, was hospitalised on February 20; the other was admitted at least two days ago.

According to the family of Rajshree Roy, the nine-month old who died on Saturday, she had fever on February 2 and was admitted to BC Roy Children’s Hospital the same day. After recovering, she was brought back home on February 11. However, on February 14, she again developed a fever. Her parents took the girl to the outpatient department and she was discharged after some treatment. According to the family, the fever did not subside and she was again admitted to hospital on February 19. She died of adenovirus pneumonia on Saturday.

1Adenoviruses can cause mild to severe illness, though serious illness is less common. People with weakened immune systems, or existing respiratory or cardiac disease, are at higher risk of developing severe illness from an adenovirus infection.

A little girl in red with flu looking sick.

Adenoviruses can cause a wide range of illnesses such as

common cold or flu-like symptoms
fever
sore throat
acute bronchitis (inflammation of the airways of the lungs, sometimes called a “chest cold”)
pneumonia (infection of the lungs)
pink eye (conjunctivitis)
acute gastroenteritis (inflammation of the stomach or intestines causing diarrhea, vomiting, nausea and stomach pain)

Less common symptoms of adenovirus infection include

bladder inflammation or infection
neurologic disease (conditions that affect the brain and spinal cord.

Adenoviruses are medium-sized (90-100 nm), non-enveloped icosohedral viruses with double-stranded DNA. More than 50 types of immunologically distinct adenoviruses can cause infections in humans. Adenoviruses are relatively resistant to common disinfectants and can be detected on surfaces, such as doorknobs, objects, and water of swimming pools and small lakes.

People with weakened immune systems are at high risk for developing severe illness caused by adenovirus infection. Some people infected with adenoviruses, especially those who have weakened immune systems, can have ongoing infections in their tonsils, adenoids, and intestines that do not cause symptoms. They can shed the virus for weeks or longer.

Specimen Collection

The types of specimens you should collect for human adenovirus detection depend on the patient’s clinical presentation and type of infection. Before collecting any specimens, discuss with a laboratory and a clinician familiar with adenovirus. To improve human adenovirus detection, you should collect specimens within a week of symptom onset.

Respiratory Infections
For respiratory infections, you should typically collect upper respiratory specimens such as a nasopharyngeal swab and/or oropharyngeal (throat) swab. If there is evidence of a lower respiratory infection, you should also collect a lower respiratory specimen such as sputum. In some instances, a serum specimen may be helpful.
Eye Infections
If there is clinical evidence of a conjunctival or eye infection, you should collect a conjunctival swab.