(CNN) -- The death toll from Pakistan's massive flooding has climbed to 1,639, but the number could rise substantially as flood waters recede and more bodies surface, government officials say.
More than 17 million Pakistanis -- about the population of the Netherlands -- have been affected by the monsoon floods that began a month ago.
In the past few days, at least 1 million people have been displaced in Pakistan's Sindh province, the United Nations said. Authorities issued evacuation orders after a levee burst.
Homeless families stomped through filthy waters as clean water remains a scarce commodity. Hundreds of thousands of victims have acquired transmittable ailments such as acute watery diarrhea, scabies and respiratory infections.
The United Nations says more than $1 billion has been given or pledged. On Saturday, the United States announced the deployment of 18 additional helicopters to assist with relief efforts, according to the U.S. Embassy in Islamabad, Pakistan. CNN
