Bangladesh is battling severe floods that have killed 51 people and affected over a million. Here is what we know.

The scale: the Ministry of Disaster Management and Relief says 1,022,963 people across 20 districts are affected. Cox’s Bazar is worst hit with 28 deaths.

The response: 1,131 shelters are open, housing 44,457 people. Prime Minister Tarique Rahman has put the administration on maximum alert.

The cause: days of heavy monsoon rain swelled river systems, damaging homes, crops and roads. Bangladesh floods almost every year, but this year’s toll is among the higher recent ones.

The risks: officials fear the toll could rise as reports come in from remote areas. Waterborne disease is the next threat once waters recede.

The context: early warning systems and cyclone-style shelters have cut flood deaths sharply over the decades, but climate change is making extreme rainfall more frequent.

Relief officials say the immediate priority is clean drinking water, as floodwater contaminates wells and ponds. Medical camps are being set up in the shelters to prevent outbreaks of diarrhoea and skin infections.