Shahdadkot, Pakistan (CNN) -- For almost a million Pakistanis, the misery of epic flooding covering one-fifth of the country has now taken the form of communicable illnesses.

Cases of acute diarrhea have topped 204,000, the World Health Organization announced Sunday. The number of skin diseases -- such as scabies -- has topped 263,300.

More than 204,600 Pakistanis have reported acute respiratory infections as filthy waters surround homeless flood victims, WHO said.

Thousands have cases of suspected malaria.

"Strong water and sanitation interventions, such as providing clean drinking water supply and addressing environmental hazards, are urgently needed to prevent outbreaks of waterborne diseases in" Charsadda, Nowshera and Peshawar, WHO said.