A young dengue patient plays with a smartphone. AP

Five-year-old Mohammad Ahnaf lies in a makeshift bed in the balcony of a major hospital in Bangladesh's capital Dhaka, fighting for his life as dengue fever ravages his little body.

But his mother Shimul Akhter knows he is one of the lucky ones as Bangladesh grapples with it’s worst-ever outbreak of the viral fever — 23 have died and many cannot get access to medical help at all.

Since January, almost 30,000 people have been hospitalised with the disease nationwide, and in the past week some 2,000 patients a day have been admitted to hospitals.

"The situation is like an epidemic. But no-one is admitting it," one expert, who asked to remain anonymous, said adding the real number of those with dengue was likely to be several times higher than official figures, which are based on limited data.

Bangladeshi children suffering from dengue fever. AFP

Facilities are struggling to cope with the influx — mattresses line every inch of spare floor extending beyond wards into corridors and balconies.

Dengue, which causes flu-like symptoms, can be deadly if it develops into a haemorrhagic fever. There is no vaccine or any specific medicine to treat dengue, according to the World Health Organisation.

Authorities are worried the situation is set to worsen.

National disaster

With the upcoming Eid al-Fitr holidays, the fever could spread to remote villages as tens of millions of people head back to rural areas to celebrate the Muslim festival.

A municipal worker sprays insecticide to kill mosquitoes in Dhaka. AFP

At Suhrawardi Medical College Hospital in central Dhaka where Ahnaf has been admitted, all the wards are full of dengue patients.

New arrivals are given whatever open space is available in the hospital.

The head of Bangladesh's National Health Rights Society, renowned doctor Rashid-e-Mahbub, said the "national disaster" was in part caused by the lack of anti-mosquito measures before the annual monsoon season.

A Bangladeshi child suffering from dengue fever receiving treatment. AFP

The country's health department said some 23 people have died so far, although it has cautioned the official fatality figures are low due to a slow validation process.

But mass circulation Bengali daily Prothom Alo said the death toll was nearly 100.

Meanwhile, Akhter fears for her family's health. The hospital doesn't have a dedicated paediatric intensive care unit to handle severe cases such as Mohammad.

She says: "We are very much scared. My elder boy is still not out of danger. Now he (younger son) felt warm this morning. I hope he has not caught dengue."

Agence France -Presse