The flooding crisis in Pakistan keeps growing worse. One-fifth of the country remains soaked, and the public health implications have started to spread:

As Pakistan reels from its worst floods in memory, United Nations officials said Monday that 3.5 million children and infants were at a particularly high risk of diseases borne by dirty water.

“Clean water is an urgent need,” said Maurizio Giuliano, a United Nations spokesman, who said the international agencies dealing with children and health were both suffering from shortages of funds. The United Nations, whose secretary general, Ban Ki-moon, flew over flooded areas of Pakistan on Sunday, has appealed for international donations of $460 million, but only one-third of that of that has been provided, Mr. Giuliano said in a telephone interview.

“There was a first wave of deaths caused by the floods themselves,” Mr. Giuliano said. “But if we don’t act soon enough there will be a second wave of deaths caused by a combination of lack of clean water, food shortages and water-borne and vector-borne diseases.”

He said as many as six million people were at risk of diseases including diarrhea-related illnesses and dysentery, typhoid and forms of hepatitis.

“We may be close to seeing this second wave of death,” he said. “The picture is a gruesome one.”

The international response has been described by UK deputy Prime Minister Nick Clegg as “absolutely pitiful.” Only one in six Pakistanis in need of clean water would be able to get it, given the current relief funding levels. In addition to water treatment, lots of other physical infrastructure – roads and bridges, radio and broadcasting towers – has been damaged severely.

I hope McClatchy is being hyperbolic when it talks about fears of the country’s collapse, but the governmental response has been so weak, and the dangers in Pakistan so great, that this would have to be seen as at least a possibility.

The humanitarian and economic disaster caused by the worst floods in Pakistan’s history could spark political unrest that could destabilize the government, dealing a major blow to the Obama administration’s efforts to fight violent Islamic extremism.

The government’s shambling response to floods that have affected a third of the country has some analysts saying that President Asif Ali Zardari could be forced from office, possibly by the military, which has ruled Pakistan for more than half its 63-year history.

Other experts caution that the state itself could collapse, as hunger and destitution trigger explosions of popular anger that was already seething over massive unemployment, high fuel prices, widespread power outages, corruption, and a bloody insurgency by extremists allied with al Qaida.

There are rumors that the military is looking to a national government, basically delivering the country straight back to the Musharraf era. And given what we know about military ties to the Taliban, that would make a total mockery of the effort to “deny safe havens” in the region.

You’d think that the President would want to make a statement about this.

UPDATE: I should add here that American relief efforts in Pakistan have generally been strong. With 1/5 of the country flooded, surely Pakistan could use more help, though.